a dissertation submitted to the graduate division of … · ecology, impact and traditional...
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ECOLOGY, IMPACT AND TRADITIONAL KNOWLEDGE OF RESIN
HARVEST ON THE WILD DAMMER TREE-CANARIUM STRICTUM ROXB. IN
THE NILGIRI BIOSPHERE RESERVE, WESTERN GHATS, INDIA
A DISSERTATION SUBMITTED TO THE GRADUATE DIVISION OF THE
UNIVERSITY OF HAWAI‘I AT MᾹNOA IN PARTIAL FULFILLMENT OF THE
REQUIREMENTS FOR THE DEGREE OF
DOCTOR OF PHILOSOPHY
IN
BOTANY
AUGUST 2014
By
Anita Varghese
Dissertation Committee:
Tamara Ticktin, Chairperson
David C. Duffy
Jefferson Fox
Orou Gaoue
Christopher A. Lepcyzk
Keywords: non timber forest produce, resin, harvest, traditional ecological
knowledge, mixed effects models, phenology, Canarium strictum, Nilgiri biosphere
reserve
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ACKNOWLEDGEMENTS
This intense journey of the past years would not have been possible without
grace from the Almighty and support, and encouragement of family, friends, teachers,
colleagues and institutions. To all of them I remain deeply grateful and wish to
express my heartfelt gratitude.
My committee members – Dr Tamara Ticktin (Chairperson) for her
unflinching faith in her student’s abilities and for being the wonderful person she is.
Drs David Duffy, Jefferson Fox, Christopher Lepcyzk and Orou Gaoue for comments,
suggestions, ideas and encouragement.
My family and friends- Parents, daughter, sister, nieces, brother in law and
cousins for their support and faith in what I do. My daughter, Merab who helped me
set out on this journey and was there to help me take it to the end point. Friends and
neighbours in Kotagiri – Pratim, Sneh, Mathew and Annie, my motivators and my
local guardians. Pastor and members of the Union Church in Kotagiri, who have been
a source of strength. Chamanlalji and Shipradi, for their blessings and countless
lessons about life. Mari and Stan, from Gudalur for their encouragement. Anu, Sunita,
Kochu, Durga – friends for a long time. Teachers at Rishi Valley School, who
adopted Merab as their own. Hawaii my home away from home and so much like my
home. Tamara, Gustavo and Ylang, my family away from family. Vandana, Lisa,
Isabel, Alesandre, Jennifer, Daniela, Georgia, Natalie, Katie, Gioconda, Shimona –
for the learning times and fun times. A special word for Jennifer my constant ‘J-seek’.
The Botany department at UHM - a great place to be and Dr. Tom Ranker, Dr.
Alison Sherwood and Ms Patty Bedoya have been especially supportive.
My organisation – Keystone Foundation- a small NGO with big ideas - an
inspiring place to be. Sneh, Pratim and Mathew – founders who shared their dreams
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with me. My team members especially Sumin, colleagues and well-wishers who have
made the place so vibrant. For help in field work that I received from Aradukuttan,
Mahadesh, Sudhakar, L. Rajendran, Senthil Prasad, Maya,Vasu, Punit, Rajan, Karian,
Rangasamy, Rangan, and Lingan.
My funding agencies – The East West Center, PEO International Scholarship,
East West Center Summer Research Grant, Jean E Rolles Scholarship, UH
Foundation Grants, Ruffords Small Grants, Botany in Action-Phipps Conservatory,
Mohammed bin Zayed species conservation fund, and Keystone Foundation.
Many people knew from a long time that I should get out and do my PhD and
I am grateful to them for their advice – Tony Cunningham who started this idea,
Pratim Roy who nurtured it, Tamara Ticktin who welcomed it and Patricia Shanley
who helped me take that final decision.
I deeply miss my good friends, T.Kunhimohammed and S.S.Manoharan who
were there when I started out but are not here on earth to see this journey reach its
destination.
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ABSTRACT
Harvest of plant products from the wild are an important source of livelihood
to millions of people who live near forests. The impact of harvesting occurs at many
levels to the ecology of the species. Harvesters are guided by their traditional
ecological knowledge that also aids in reducing the impact of the harvest. I use the
case study of Canarium strictum Roxb, (Burseraceae) a semi-evergreen tree harvested
for resin by several indigenous communities in the Indian subcontinent. Resin is used
locally for rituals and healing purposes and traded widely for industrial uses. I
investigated the effects of resin harvesting on the ecology and phenology of the
species on 89 trees in three regions of the Nilgiri Biopshere Reserve, Western Ghats,
for two years. Seed germination experiments with seeds from harvested and not
harvested trees were also undertaken. Through focus group discussions with
harvesters, and using a fuzzy logic approach I documented their perceptions on the
ecology of resin harvest and trees. I found that harvesting practices, size of the tree
along with the characteristic of the tree flush colour were significant predictors of
resin harvest. My results show that harvesting of resin has no negative effect on the
growth rate, and fruit production. However harvested trees flowered at different times
from not harvested trees and showed increased fruit production and seed germination
rates. I found that resin harvesting was a prevalent practice among the indigenous
people of the region and many of the factors perceived by the harvesters to influence
resin quality and status of resin tree numbers in the forest coincided with factors
observed in the ecological studies. Overall my results suggest that harvesting of resin
has relatively low impact on the ecology of C. strictum and harvesters of resin make
decisions on resin harvest based on a number of ecological factors. My results
illustrate some of the detailed knowledge that harvesters have with regard to a lesser
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studied species like C. strictum, and community based monitoring programs that build
on this knowledge can ensure strategies that allow for sustainable use while meeting
the goals of conservation.
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TABLE OF CONTENTS
ACKNOWLEDGEMENTS ....................................................................................... II
ABSTRACT ............................................................................................................... IV
LIST OF TABLES ................................................................................................. VIII
LIST OF FIGURES .................................................................................................... X
CHAPTER 1. INTRODUCTION ............................................................................... 1
Overview .................................................................................................................... 1
Nilgiri Biosphere Reserve (NBR), Western Ghats India ........................................... 2
Impacts of harvesting from the wild .......................................................................... 3
People and forests in India ......................................................................................... 5
Community based ecological monitoring .................................................................. 6
Research questions and dissertation outline ............................................................... 8
CHAPTER 2 - IMPACT OF RESIN HARVEST ON THE BIOLOGY OF
CANARIUM STRICTUM ROXB .............................................................................. 10
Introduction .............................................................................................................. 10
Materials and Methods ............................................................................................. 13
Results ...................................................................................................................... 18
Discussion & Conclusion ......................................................................................... 20
CHAPTER 3 - PHENOLOGICAL PATTERNS IN CANARIUM STRICTUM
ROXB. (BURSERACEAE), A RESIN HARVESTED SPECIES OF THE
NILGIRI BIOSPHERE RESERVE, WESTERN GHATS, INDIA ...................... 29
Introduction .............................................................................................................. 29
Materials and Methods ............................................................................................. 31
Results ...................................................................................................................... 35
Discussion ................................................................................................................ 39
CHAPTER 4. TRADITIONAL ECOLOGICAL KNOWLEDGE OF RESIN
GATHERERS OF THE NILGIRI BIOSPHERE RESERVE, WESTERN
GHATS, INDIA .......................................................................................................... 55
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Introduction .............................................................................................................. 55
Materials & Methods ................................................................................................ 58
Results ...................................................................................................................... 63
Discussion ................................................................................................................ 67
CHAPTER 5. CONCLUSIONS ................................................................................ 85
Main findings ........................................................................................................... 85
Contributions to scientific literature ......................................................................... 89
Future directions ....................................................................................................... 92
APPENDIX.A. MAPS OF STUDY REGIONS WITH APPROXIMATE
LOCATION OF SITES ............................................................................................ 95
APPENDIX B. PHOTOS OF STUDY SITE, RESIN, RESIN TREE, AND
HARVEST METHODS ............................................................................................. 96
APPENDIX C. DETAILS OF METHODS AND RESULTS FROM THE
LINEAR MIXED EFFECTS MODELS ON PREDICTORS OF RESIN
HARVEST AND EFFECT OF RESIN HARVEST ON GROWTH, FRUIT
PRODUCTION AND SEED GERMINATION ON THE WILD DAMMAR
TREE (CANARIUM STRICTUM) .......................................................................... 100
APPENDIX D UNIVERSITY OF HAWAIʻI COMMITTEE ON HUMAN
SUBJECTS RESEARCH EXEMPTION .............................................................. 102
BIBLIOGRAPHY .................................................................................................... 103
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LIST OF TABLES
Table.2.1. Characteristic of 89 Canarium strictum trees in relation to harvest
methods, percentage harvested, quantity or resin yielded and size of tree across three
regions of the Nilgiri Biosphere Reserve ..................................................................... 24
Table.2.2. Predictors of harvest status (yes/no) of C. strictum trees from a binomial
generalized linear mixed effects model. ...................................................................... 25
Table.2.3. Predictors of quantity of resin harvested/tree in C. strictum trees over a two
year period, from a general linear mixed effects model with a negative binomial error
structure........................................................................................................................ 25
Table.2.4. Predictors of growth of C. strictum trees from a linear mixed effects
model............................................................................................................................ 26
Table.2.5. Predictors of quantity of fruit produced in C. strictum trees from a
generalized linear mixed effects model with a negative binomial error structure. ...... 27
Table.2.6. Predictors of the probability of C. strictum seed germination from a
binomial linear mixed effects model. ........................................................................... 27
Table.2.7. Summary table of predictors of resin harvest and effects of harvest on
growth, germination, and fruit production in C. strictum ............................................ 28
Table.3.1. Characteristics of Canarium strictum trees – Percent of trees in different
conditions during study period..................................................................................... 45
Table.3.2. Effects of size as determined by diameter at breast height, openness of
canopy and location on the colour of flush in Canarium strictum trees from a binomial
generalized linear mixed effects model. ...................................................................... 46
Table.3.3. Observations of animals dependant on the Canarium strictum tree, flush,
flower or fruit ............................................................................................................... 47
Table.4.1. Details of harvester villages, communities, access, quality of resin and
market price of resin across four regions in the NBR .................................................. 75
Table.4.2. Factors affecting resin quality as perceived by resin harvesters from
Chamrajnagar region, arranged in fuzzy logic sets ...................................................... 76
Table.4.3. Factors affecting resin quality as perceived by resin harvesters from
Chamrajnagar region, arranged in fuzzy logic sets ...................................................... 77
Table.4.4. Factors affecting resin quality as perceived by resin harvesters from
Kotagiri region, arranged in fuzzy logic sets ............................................................... 78
Table.4.5. Factors affecting resin quality as perceived by resin harvesters from
Nilambur region, arranged in fuzzy logic sets ............................................................. 79
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Table.4.6. Factors affecting number of resin trees as perceived by resin harvesters
from Coonoor region, arranged in fuzzy logic sets..................................................... 80
Table.4.7. Factors affecting number of resin trees as perceived by resin harvesters
from Kotagiri region, arranged in fuzzy logic sets ...................................................... 81
Table.4.8. Recent changes in resin harvest methods across the four regions in the
NBR ............................................................................................................................. 82
Table.4.9. Summary of factors perceived by resin harvesters important to resin
quality .......................................................................................................................... 83
Table.4.10. Summary of factors perceived by resin harvesters important to number of
trees. ............................................................................................................................. 83
Table.4.11. Comparison of perceptions in Traditional Ecological Knowledge and
findings in Ecological studies in relation to aspects of resin harvest and resin trees .. 84
Table C.1. Specifications of full linear and generalised linear mixed effects models
(LMM and GLMM) used to predict resin harvest and effect of resin harvest on growth
fruit production and seed germination in C. strictum ................................................ 100
Table C.2. Estimates and standard errors for main effects and interactions that were
non-significant (p>0.05) by likelihood ratio test during model reduction in Chapter 2.
All terms were significant in Growth model.............................................................. 101
x
LIST OF FIGURES
Figure. 3.1. Rainfall (mm) over 2011-12 in three study regions located in the Nilgiris
district of the Nilgiri Biosphere Reserve ..................................................................... 48
Figure.3.2 Phenology of Canarium strictum trees located in 5 sites in 3 regions of the
NBR across a two year period ..................................................................................... 49
Figure.3.3. Percent of harvested and not harvested trees in flush across three regions
of the NBR in 2012-13 ................................................................................................. 50
Figure.3.4. Percent of harvested and not harvested trees in flower across three regions
of the NBR in 2012-13 ................................................................................................. 51
Figure.3.5. Percent of harvested and not harvested trees in fruit across three regions
of the NBR in 2012-13 ................................................................................................. 52
Figure.3.6. Total amount of resin harvested across two years from Canarium strictum
trees in three regions across the NBR .......................................................................... 53
Figure.3.7. Distribution of Canarium strictum trees with green and red flush in
relation to diameter at breast height ............................................................................. 54
B.1. Vegetation characteristics of study sites .............................................................. 96
B.2. Grades of resin found in the region ...................................................................... 97
B.3. Characteristics of resin tree, Canarium strictum .................................................. 98
B.4. Resin harvesting tools and practises..................................................................... 99
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CHAPTER 1. INTRODUCTION
Overview
Balancing the goals of human development with conservation of biodiversity
gained momentum in the past three decades with the release of the Brundtland
Commission report of the United Nations which described conservation and
development as “opposite sides of the same coin” (WCED, 1987). The need to strike
this balance by reducing poverty and stemming biodiversity loss became global
challenges echoed in the Convention on Biological Diversity and the Millenium
Development Goals (Barrett et al, 2011). Poverty was seen as the cause for
environmental degradation though this view has increasingly been discounted in
recent times when all the social, political, economic and ecological factors are taken
into account (Barrett, et al, 2011; Duraiappah, 1998; Wunder, 2001).
An estimated 1.5 billion people world over are dependent on forests for their
livelihoods (Chao, 2012) and forest incomes contribute between 20-27% of the
household incomes (Vedeld, et al, 2004; Wunder, 2014). In many forest based
livelihood interventions, development goals have been achieved to some level, but not
so with conservation goals (Belcher & Schreckenberg, 2007; Morsello,et al, 2012).
High dependence on forests does not necessarily mean high levels of conservation
especially in relation to species that are of high conservation priority but not of
immediate use (Freese, 1997; Madhusudan & Shankar Raman, 2003). A relook at
conservation by defining it in a more robust way to include approach, management,
incentive, and knowledge can be seen as a way forward in improving community
based conservation (Berkes, 2004).
Associating forest dependence to incomes has meant that cultural practises,
healing traditions, wild food consumption, sacred spaces, cultural identity and
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traditional knowledge benefits from the forest has received less attention. These
benefits have a direct link to the quality of forest dependant people’s lives and support
a system of knowledge, practise and belief also defined as their traditional ecological
knowledge (Berkes, 1999). This knowledge not only helps indigenous communities
survive in the forests around them but also defines their cultural beliefs and practices
( Gadgil, 1992).
In my dissertation I seek to understand the impact of harvests and traditional
ecological knowledge of, a wild harvested species of cultural and economic
importance. I use the case study of the dammar tree (Canarium strictum Roxb.) from
which resin (also known as ‘dhupa’ locally and frankincense commonly) is collected
for local consumption and trade. I study the effects of harvesting on the ecology and
phenology of the species, with specific observations on the timing of leaf flush,
flowering, fruiting, and on growth rates, seed germination, fruit production and
survival. I explore the traditional ecological knowledge with regard to resin harvest of
the indigenous people who harvest the resin. My study seeks to establish linkages
between science and traditional ecological knowledge in order to create a foundation
for a long term community based ecological monitoring program for a biosphere
reserve located within a biodiversity hotspot.
Nilgiri Biosphere Reserve (NBR), Western Ghats India
The Western Ghats, also known as the Sahyadri Hills are a 1600 km long
mountain range along the west coast of India and cover approximately 1,40,000 sq
km. The region was declared a biodiversity hotspot in 1988 and is under threat from
developmental activities related to agriculture and urbanization and has a density of
267 people/sq. kms of area, highest for the biodiversity hotspots of the world
(Cincotta, et al, 2000; Das et al., 2006). A recent report commissioned by the
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Government of India on conservation measures for the Western Ghats has become
controversial, as vested interests have portrayed the report as anti- development
leading to much debate and civil unrest (Gadgil, 2014)
The Nilgiri Biosphere Reserve (NBR) is part of the Western Ghats and lies
between 100 45’N to 12 0 N and 760 E to 770 15’ E with a total area of 5520 sq.km
spread across the three southern states of Karnataka, Kerala and Tamil Nadu. The
region was designated as a biosphere in 1986 by the Man and biosphere program of
the United Nations. Both the Western Ghats and the NBR are home to mega fauna
like the Asian Elephant (Elephas maximus) and the tiger (Panthera tigris) and are
known to have a long history of human land-use, more than 12,000 years (Subash
Chandran, 1997). In the region of the NBR there are over 20 distinct indigenous (‘
adivasi’) people groups with a total population size of nearly 2,00,000 (Keystone
Foundation, 2007). Many communities live close to the forests and are well
recognised for their forest related skills, especially of honey hunting (Demps, et al,
2012; Roy et al., 2011).
Impacts of harvesting from the wild
Plant products from the wild are harvested extensively and intensively
(Shackleton, 2010). NTFP are defined here as goods, other than timber and firewood,
of plant origin and derived from forests which may be used directly, such as food,
fibre, medicine and construction materials or processed further to yield oils, soap
substitutes and other commodities; and these products may be traded for money or
bartered for other goods and services (De Beer and McDermott, 1996). Management
of non-timber forest products (NTFP) gathered momentum world over as a means of
poverty alleviation through localized value addition initiatives, catalysed by research
from the Peruvian Amazon by Peters et.al (1989), which showed that the income from
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sustainable NTFP collection was more than returns from timber harvesting or any
other alternative land uses. Increasingly traditional sustainable harvest practises of
NTFP as practised by many communities across the world is being documented and
management recommendations have sought to bring those practises on board (Ticktin
et al, 2010).
NTFP harvest systems can have ecological impacts at multiple ecological
scales, from individuals to ecosystems and consequences of harvest depend on many
factors, including the part(s) of the plant harvested, the life history characteristics of
the species, the nature and intensity of harvest and/or management practices, and the
larger socioeconomic, political and ecological context from which the products are
harvested (Cunningham 2001, Ticktin et al, 2012). NTFP harvest sustainability
requires not only that NTFP populations are able to persist over the long-term, that
but also that harvest does not negatively affect community and ecosystem functions.
In reality, both the management and ecological impacts of harvesting any given
species can vary enormously across space and time (e.g. Nantel et al. 1996; Siebert
2000; Gaoue & Ticktin 2007). High dependence of local communities on NTFP has
been reported to be a cause for loss of forest cover and forest degradation in the
Western Ghats (Davidar 2008, Karanth et al. 2006). However recent studies in the
region have also shown that harvest of NTFP has less detrimental effects on the
population dynamics of the species than previously thought (Ticktin et al, 2012) and
there is a need to consider the multiple processes that may be affecting harvested
populations (Mandle et al, 2013).
Plant exudates like gums and resins are important NTFPs that have a number
of uses in medicine, ritual, industry and early records of its use are reported from
Arabia-1000 BC and Mayan civilisation - 600 BC (Langenheim,2003). Trees produce
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resin for a number of reasons, primarily to avoid auto toxicity, defend themselves
from parasites, and prevent herbivory (Langenheim, 2003). Resins also play a role in
attracting pollinators and seed dispersers (Langenheim, 2003). Research has shown
that harvesting resin impacts conduction of nutrients and hormones involved in the
production of flower buds (Primack 1987); reduces number of fruits and viable seeds
(Rjikers 2006) and keeps populations in a vegetative state (Cunningham & Mbenkum,
1993; Cocks & Dold, 2004). In contrast some studies show that removal of resin or
other exudates including latex, did not affect the flower or fruit production (Bitariho
et al 2006; Schumann et.al 2010; Bladauf et al 2014).
Canarium strictum Roxb., is a heavily harvested Indian resin tree, which
produces the resin known as ‘black dammar’. C. strictum is a semi evergreen tree,
found in the wild and rarely in cultivation, distributed unevenly along the Western
Ghats and other parts of India. Information about its conservation status nationally or
globally is lacking, though at the level of the region C. strictum has been reported to
be a species of conservation concern (Ravikumar et al, 2000). Typically, resin is
either collected opportunistically from trees where is has gathered, or by making
incisions and returning to collect resin after a period of time. In some regions,
harvesters set fire at the base of the tree to increase resin production before making
incisions (Varghese et al 2008).
People and forests in India
India has only 2% of the world’s forests and nearly 21% of the country’s total
land cover is under forests (Varadarajan, 2014). An estimated 100 million people are
forest dependent in India (Kabra, 2009) of which close to 89 million are indigenous or
adivasi people who have close cultural and economic links with the forests (Census of
India, 2010). The National Medicinal Plant Board of India estimates about 960
6
species of medicinal plants are used in trade, of which 178 species have annual
consumption levels in excess of 100 metric tonnes and exports in the range of INR 10
billion (http://nmpb.nic.in/index.php). The bulk of the published research on wild
plant harvests in the Western Ghats, show that the harvested species are on the decline
(Ravikumar & Ved 2000).
In the NBR studies have shown that upto 40% of incomes of indigenous
people come from the forests (Pain, 2009). This high use of the forests linked to
conservation has been identified as a priority research area in tropical conservation
(Bawa et al, 2004). Participation of forest-dwelling indigenous communities in the
conservation process is undergoing a rapid change in the Indian context due to the
recently implemented Scheduled Tribes and Other Traditional Forest Dwellers
(Recognition of Forest Rights) Act, 2006 also referred to as the Forest Rights Act of
2006. The Act broadly provides for two sets of rights – land rights, both private and
common, and community rights over forest resources. Community rights over forests
include rights over grazing lands, NTFP collection areas and other common property
resources. The Act also provides for declaration of critical wildlife habitats and the
preservation of threatened species or habitats. This law recognises the local
communities rights to manage natural resources and biodiversity and provides
opportunities to jointly manage biodiversity along with the state (Bawa, et al, 2011).
Community based ecological monitoring
Indigenous users of natural resources are guided by their traditional ecological
knowledge which deals with complexity through rules of thumb and indicators which
are used to simplify the questions, consistent with fuzzy logic thinking (Berkes 2009).
Fuzzy logic models allow management of complex non-linear systems traditionally
with industrial process and more recently with ecological, economic and geophysical
7
systems by offering more opportunity to use human judgment (Zadeh 2008). Fuzzy
logic uses language variables ‘And If Then’ rules to bring precision into imprecise
information (Zadeh 2008).
Monitoring has been defined as “the systematic measurement of variables and
processes over time” and “assumes that there is a specific reason for that collection of
data, such as ensuring that standards are being met” (Spellerberg, 2005). Monitoring
is one way that conservationists rely on traditional wild produce harvester
communities to be partners in sustainability, although this alone may not be enough
and we need to find a complementarity between science and the traditional ecological
knowledge of the harvesters (Moller et.al 2004).
To identify the effects of anthropogenic factors on ecological process it is
important to monitor them over the long term. Phenology of plants, pollinator
preferences and migratory patterns in birds are some of the more common processes
that have been monitored. Biologists have relied a lot on participation of amateur
naturalists, citizen groups and interested individuals from all walks of life
(Greenwood, 2007; Ledneva, Miller-Rushing, 2004). There is a need to link
monitoring with local decision making processes, which in turn will make the
monitoring sustainable and effective (Danielsen, 2005) . In developing countries
fewer resources are available for these voluntary monitoring schemes and therein lies
the challenge in designing effective, cost efficient methods (Danielsen et al 2005).
Locally based monitoring may be the ideal way for communities to report to external
agencies on progress with managing habitats, species, and flows of ecosystem
services in community or co-managed conservation areas (Danielsen et. al 2008). An
opportunity in conservation-linked field studies lies in the use of local and indigenous
knowledge, ensuring benefits to the people while meeting the goals of conservation.
8
In the past, ecological monitoring was an integral part of traditional resource
management practices in indigenous communities, many of which involved adaptive
management and were highly effective at conservation (Moller et al, 2004).
Research questions and dissertation outline
In order to investigate the effects of harvest on the ecology and phenology of a
wild resource and explore how the harvesters of the region understand the ecology of
the species, I present a case study of C. strictum to ask :
1. What affects the probability that a tree (C. strictum) will be harvested for resin
or not? How does harvest impact the vital rates (growth, reproduction and
survival) of C. strictum?
2. What are the regional variations in phenology of the C. strictum, and does
harvest impact the phenology?
3. What is the traditional knowledge that exists about C. strictum and how can it
form part of ecological monitoring?
Chapter 2 of this dissertation deals with the impact of harvest on the vital rates
of the wild dammar tree. I present the results of a two year study on drivers of resin
production, resin harvest, growth, fruit production and germination in 89 C. strictum
trees located in five locations across the NBR.
In Chapter 3, I present the results of observations done on the phenology (leaf
flush, flowering, fruiting) of C. strictum trees and compare patterns between harvested
and not harvested species.
In Chapter 4, I use the fuzzy logic approach to present the results of discussion
that were held with resin harvesters on their knowledge in relation to resin quality and
trees. This chapter also examines how this knowledge is changing and adapting
9
In Chapter 5, I conclude by synthesizing my findings from the preceding
chapters and discuss their implications for the conservation of a lesser studied species
by including harvester communities in the monitoring of the species and its habitat. I
summarise the contributions of my research to the fields of conservation biology and
human ecology, discuss the limitations of my study and suggest future lines of
research for integrating traditional knowledge in biodiversity conservation.
10
CHAPTER 2 - IMPACT OF RESIN HARVEST ON THE BIOLOGY OF
CANARIUM STRICTUM ROXB
Introduction
Plant products from the wild have been harvested extensively and intensively
across the world (Cunningham, 2011). The practice of collecting non timber forest
products (NTFP) is an important part of the lives of some of the most marginalized
communities of the world (Shackleton et al 2011). NTFP are defined here as goods,
other than timber and firewood, of plant origin, derived from forests which may be
used directly, such as food, fibre, medicine and construction materials or processed
further to yield oils, soap substitutes and other commodities and these products may
be traded for money or bartered for other goods and services (De Beer and
McDermott, 1996). Management through localized value addition of NTFP gathered
momentum world over as a means of poverty alleviation, catalysed by research from
the Peruvian Amazon by Peters et.al (1989), which showed that the income from
sustainable NTFP collection was more than returns from timber harvesting or any
other alternative land uses. Harvest of NTFP is reported to be the cause of population
decline in a number of plants globally (Brummit and Bachmann, 2010). However,
many NTFP, including those harvested for national and international sales, can be
harvested sustainably (Ticktin & Johns, 2001; Schmidt & Ticktin, 2012; Schmidt et
al. 2011).
Sustainable harvest of NTFPs can only be possible if the impacts of harvest at
multiple ecological scales, from individuals to ecosystems, part(s) of the plant
harvested to its life-history characteristics are taken into account (Ticktin, 2004).
Management practices, socio-economic, political and ecological context from which
the products are harvested need to be considered when assessing the impacts of NTFP
11
harvest (Cunningham, 2001; Ticktin and Shackleton, 2011). For NTFP harvests to be
sustainable it is critical that targeted plant populations are able to persist over the
long-term, but also that harvest does not negatively affect community and ecosystem
functions. In reality, both the management and ecological impacts of harvesting any
given species can vary enormously across space and time (e.g. Nantel et al. 1996;
Siebert 2000; Gaoue & Ticktin 2010).
Plant resin, as an NTFP, has an important societal value and has been part of
human cultures for a long time. Plant resin is used as such in medicine, and rituals,
and processed for industrial uses related to the paint and varnish industry
(Langenheim, 2003). Trees produce resin for a number of reasons, primarily to avoid
auto toxicity, defense from parasites and herbivores and also to attract pollinators and
seed dispersers (Langenheim, 2003). The high cost of production to the plant, of this
primary metabolite is offset by the benefits of pollination, dispersal and defense from
pathogens for the tree. Harvesting or removal of resin, can impact conduction of
nutrients and hormones involved in the production of flower buds (Primack 1987);
reduce number of fruits and viable seeds (Rjikers 2006) and keep populations in a
vegetative state (Cunningham & Mbenkum 1993, Cocks & Dold 2004). In contrast
some studies show that removal of resin or other exudates including latex does not
affect the flower or fruit production (Bitariho et al 2006; Schumann et.al 2010;
Bladauf et al 2014). However, this has not been widely studied and the general
patterns remain unclear. Collection of plant exudates, if harvested in prescribed ways
(either by traditional knowledge or scientific practices), has the least impact on the
species and its populations as compared to harvest of other vegetative or reproductive
parts (Peters, 2001).
12
Worldwide, resin has traditionally been harvested by tapping the tree which is
a controlled wounding of the tree (Langenheim, 2003). Resin flow in lodge pole pine
(Pinus contorta) is influenced by wound size, diameter of the tree and tree health
(Nebeker et al, 1995). Studies that have looked at traditional practices of resin
collection from South East Asia, Amazon and Africa show that resin production is
highly dependent on tree size and crown diameter (Ella and Tongacan, 1987; Newton
et al, 2010; Eshete et al, 2011). Traditional methods of resin harvest in South East
Asia involve the use of fire and tapping (Ibrahim et. al., 1987; Ella and Tongacan
1987). In the Phillipines, resin of Canarium luzonicum is harvested commercially and
though it can be collected throughout the year from the rain forest, it is preferably
harvested in the wet season when there is a greater resin flow (Langenheim, 2003).
Canarium strictum Roxb., is an important and heavily harvested Indian resin tree,
which produces the resin known as ‘black dammar’. Resin from C. strictum is
harvested for local consumption as well as for sale and the species is subjected to
different types of harvest methods and frequency across the regions where it is found
(Varghese & Ticktin 2008). Typically, resin is either collected opportunistically from
trees where it has collected naturally, or by making incisions and returning to collect
resin after a period of time. In some regions, harvesters set fire at the base of the tree
to increase resin production before making incisions (Varghese and Ticktin, 2008).
The goal of our study is to identify factors that predict patterns and quantities
of C. strictum resin harvest, and assess the effects of resin harvest on vital rates
(growth, survival, reproduction) of the tree, across three regions of the our study area.
We address the following questions: 1) What affects the probability that a tree will be
harvested for resin or not? 2) What are the predictors of resin quantity – that is, why
do some trees yield more resin than others? 3) What effect does resin harvest, along
13
with tree size, flush colour, fruiting levels, canopy openness and location have on
survival, growth, fruit production and seed germination?
We expected to find that location affected the status (harvested or not
harvested) of the trees in our study area, since in two regions harvest involves incision
making, while in the third it involves only gathering resin that has formed naturally.
We also expected that resin harvest has negative effects on the growth, reproductive
output (number of fruits produced) and germination rates of seeds, owing to
competition for resources between these processes and resin production.
Materials and Methods
Study species and site
Canarium strictum, Roxb is a lesser studied species in the wild and is found in
semi evergreen, moist deciduous and riparian forests. C. strictum populations are
distributed across the Western Ghats, parts of the Eastern Ghats, North East India into
Burma (Shashidharan, 2006). The tree is reported to be present up to an elevation of
1300m (Shashidharan, 2006). The flowers are polygamous (Gamble, 1915), though
local indigenous people maintain that there is a male and a female tree. Individual
trees can grow upto 50m (per.obs) and flush, flower and fruit gregariously. Trees are
located in clusters, and all along the Western Ghats, the tree has been harvested for its
highly valued resin which is sold as frankincense in the local markets.
Our study was conducted in the Nilgiri Biosphere Reserve (NBR) of the
Western Ghats biodiversity hotspot (Mittermerer et al 2005). We selected three
regions, Coonoor, Kotagiri and Gudalur, based on prior knowledge on location of
trees and distinct resin harvesting practices. All the regions selected were in semi
evergreen and riparian forest patches with an elevation ranging from 900-1200m
above sea level. The three regions had slight rainfall variations- Coonoor and Kotagiri
14
regions receive their maximum rainfall during the October-November period while
Gudalur region receives peak rainfall in July- August (Chapter 3). Trees in Gudalur
region were located in a coffee plantation which was more than 50 years old and has
evergreen forests adjoining the area. Within the plantation, C. strictum trees were left
to grow as shade trees and as support trees for pepper vines. In Coonoor and Kotagiri,
C. strictum was found as a secondary pioneer, often occupying tree fall gaps and
natural clearings in the forest. A fair amount of seedlings and saplings were found in
the under storey around the adult trees. All these regions were relatively closed to
disturbances from fire, grazing (domestic cattle), invasive species like Lantana
camara and could be considered relatively undisturbed forests. Other dominant
species found growing along with C. strictum are Elaeocarpus spp., Schelichera
oleosa, Mesua ferrea, Persea macarantha, and Garcinnia gummi-gutta.
Resin harvesting practices
Harvesting of resin is an ancient practice that has been part of the ritual and
traditions of the indigenous people of the NBR. The three main communities who
were observed harvesting the resin belonged to the Irula, Kurumba and Kattunayaka
people. In Kotagiri and Gudalur harvesting is done using tools like small axes and
sharp curved knives. In Gudalur, it was the practice to set a low intensity fire at the
base of the tree using dry leaf litter and burning the bark before making the incisions.
This practise has stopped since 30 years now, because of strict rules about starting
fires imposed by the forest authorities. In Kotagiri and Gudalur incisions for tapping
resin were observed to be made nearly three feet above the root and were left open for
the resin to form. In Coonoor harvesting is practiced without tapping or causing any
damage to the tree bark. Natural deposits of resin on very large trees collect at the
forks of branches or natural cracks in the bark and these were collected as soon as
15
they had hardened and were not sticky, by which time they were black in colour and
varied from 5cm to 15cm length (per.obs).
Selection of sites
We selected C. strictum trees above 25cm dbh in two sites each within a
region with the exception of Gudalur region where we were able to locate only one
site. We used 25 cm dbh as a cut-off because according to harvesters, only trees above
this approximate girth are harvested. Sites were selected based on harvester’s prior
knowledge of the area - the trees are not found evenly distributed in the forests so it
was important to locate them with the help of the harvesters. In each site we looked
for a minimum of 10 trees of which at least five were subjected to regular harvest and
others were not harvested. In the Gudalur region we were able to locate 20 harvested
and not harvested trees in total. Trees were also selected based on access for
monitoring, and this was a challenge in the Coonoor region where the access was
difficult even for the local people because of the terrain.
Data collection
In January 2012, a total of 89 trees across the three regions (Table.2.1) were
tagged and measured for dbh at the beginning of the study and subsequently every six
months for two years. We recorded the openness of the canopy (ranked as open,
partially open, and closed), height of the tree, and history of harvest of each tree.
Every 15 days, presence of absence of leaf, flush, flower, and fruit were recorded, as
well as flush colour. The bark of the tree was closely observed for fresh incisions
made for harvest of resin. The quantity of resin harvested was estimated based on
information from field assistants, who were also local resin harvesters in each region.
We undertook resin harvesting visits in all our regions to make independent
assessments of resin weights and amounts per tree, this helped in validating the
16
estimates that were being made as part of our fortnightly data collection. In 2012,
May and June we counted the number of fruits produced by all fruiting trees. An
estimate of fruit counts was done by portioning the tree crown into eight sections,
counting the fruit on five random branches in each section and estimating number of
fruiting branches for each section. Total fruit produced for the tree was then estimated
as a multiple of number of fruits/branch times number of branches times number of
sections. This estimate was always done by the principal investigator in order to
standardise counts.
Germination experiments
In 2013 between July and October, seeds were collected from all harvested
(n=27) and not harvested (n=21) fruiting trees of the five sites in three regions. Seed
collection was opportunistic and we collected a minimum of 50 seeds from each
individual tree from the forest floor for the purposes of our experiments. A total of
253 seeds from Kotagiri, 101 seeds from Coonoor and 142 seeds from Gudalur were
used as part of the experiment. Of these 239 seeds were from harvested trees and 257
from not harvested trees. Seeds were collected from directly under the crown and
closer to the tree so as to rule out the possibility of a seed being from the
neighbouring tree. We used a seed germination method which has been tried and
perfected at a local organisation that undertakes native species planting. Seeds were
treated by soaking in cold water for 7 days and left to dry in the sun for up to 3 hours,
by which time the stony exocarp has split, after which the seeds are buried in nursery
beds with a 1:3 ratio of soil to sand (L. Rajendran, unpublished nursery manual).
Germination tents were made with UV treated plastic sheets to maintain temperature
and moisture conditions. A total of 490 seeds were planted and the seeds were
watered every second day, and the number of seeds germinated were recorded at the
17
same time. When the radicle emerged from the soil, that was taken as the first day of
germination and emerging seedlings were monitored for survival over a period of 6-8
weeks.
Data analysis
We used linear and generalised linear mixed effects model (LMER and
GLMER) to model resin production, harvesting status (yes/no), growth, germination,
and fruit production of our study species (Table.C.1.) We first tested for
multicollinearity between predictors and found none of our variables to be
significantly correlated. We considered site within region as a random effect and since
this was based on spatial configuration of our study design, this was retained in all our
models. To model the probability of germination, we considered tree within site
within region as a random effect. Fixed explanatory variables included region, total
number of incisions made on the tree, total number of times a tree was harvested,
canopy openness, dbh (log transformed), flush colour (green or red) and ranked
fruiting intensity. Two way interactions of the main effects, between region, dbh and
flush colour, were also included in the full model. Ranked fruiting intensity included
none (trees produced flowers but did not fruit at all), low (trees produced very low
numbers of fruits not more than 20 per tree, and only on one or two branches) and
normal (trees produced more than 100 fruit). Fruit counts were found to be less than
20 or more than 100. To model the probability of tree survival, seed germination and
tree being harvested for resin, we used binomial GLMMs. For resin quantity and fruit
production, we used GLMMs with a negative binomial error distribution (Table C.1.).
For growth, we used a Gaussian error distribution. Fruit production data was modelled
using the data from fruit producing trees (n=48). Resin quantity data was modelled
using the data from resin harvested trees (n=26). All other models were based on data
18
from 89 trees. With the exception of fruit production, which was recorded only for
2012, and seed germination recorded only for 2013, the rest of the data were modelled
over a two year period. Full models were reduced in a backwards stepwise process ,
sequentially dropping the least significant fixed effect term in the model, and looking
at the AIC values. All analyses were completed in R.2.13.1(R Development Core
Team 2011) using the ‘lmer’ function in the lme4 package (Pinheiro et al 2011).
Results
Factors affecting resin harvest status and quantity
Nearly 50% (n=36) of the trees in the Kotagiri, 40% (n=20) in Gudalur and
20% (n=33) in Coonoor regions were harvested for resin in two years (Table.2.1). We
found that region, total number of incisions, and flush colour were significant
predictors of harvest status (Table.2.2). Region, in our study represented harvesting
method and we found trees in Kotagiri and Gudalur, where harvest was done with
incisions, were harvested significantly more than those in Coonoor. Trees that
produce green flush were more likely to be harvested than those with red flush but
when they were in a higher size class. There was a moderately significant interaction
between size of the tree and flush colour (Table.2.2.). Fruiting intensity varied widely
across regions and was not significantly correlated with harvest status (details in
Appendix C, Table.C.2).
In the two years of our study, we observed high variation in total resin
quantities that were harvested, ranging from 10kg in Kotagiri region to 44kg in
Coonoor region (Table.2.1.). At the individual tree level, annual resin yields ranged
from 0.1 to 18kg across regions. Size of the tree and number of new incisions made
were significant predictors of the quantity of resin obtained (Table.2.3.). More
incisions and larger trees yielded higher amounts of resin. Flush colour, fruiting
19
intensity and size of the tree were not significant predictors of quantity of resin
harvested (Appendix C, Table.C.2.).
Effect of resin harvest on vital rates of C. strictum
The size of resin producing trees in our study sites ranged from 25cm to 142
cm dbh across the five sites in three regions. Average dbh (cms) sizes of the resin
trees were 65±23.5 in Coonoor, 73±23.6 in Gudalur and 46±16 in Kotagiri
(Table.2.1). The final model for growth included all of our predictor variables even
though their effect sizes were very small (Table.2.4). The variable with the biggest
effect sizes was initial size (dbh of year one). Trees that produced lesser fruits and
were in open canopy conditions were found to have lower growth rates. Tree size and
red colour flush showed a negative interactive effect on growth of the tree.
Across the 48 trees that produced fruit in 2012, the mean (±SD) number of
fruits counted was 8 ±7 in trees that fruited at a ‘low’ level and 470±296 in trees that
fruited ‘normally’. Tree size and resin harvest status (harvested and not harvested)
significantly predicted the probability of germination. Trees with red flush also
produced significantly more fruit than trees with green colour flush. Finally the
harvested trees produced significantly more fruit than not harvested trees. There was
no significant interactive effect of flush colour and tree size on fruit production.
Region and canopy status were not significant predictors of number of fruits produced
(Appendix C, Table.C.2).
Seed germination rate, mean percentage (±SE) was significantly higher in
harvested trees, 48% (±6.9) than in not harvested trees, 23% (±4). We found that size
of the tree, and harvest status (harvested and not harvested) were significant
predictors of the probability of germination. Seeds that were collected from trees that
were harvested for resin showed higher germination rates than seeds collected from
20
trees that were not harvested for resin. Seeds collected from larger trees had a lower
germination probability than those from smaller trees.
Over our two year observation period, six out of 89 trees died, all of which
were harvested for resin. These dead trees were larger trees with dbh ranging from
40-140 cm. While two out of the six died because of other trees falling on them, four
of them started to dry up and fell in the rain period. Even as we finished our
monitoring in January 2014 we noticed that one more tree which was near a stream
but was also a harvested tree, had started to show signs of drying up. However, none
of our explanatory variables were significant predictors of the probability of survival.
Discussion & Conclusion
Our study on C. strictum harvests in the NBR show some variation across
regions in terms of resin harvest but harvesting of resin did not have significant
negative effects on the vital rates of the tree (Table.2.6).
Selection of trees to harvest resin
Tree characteristics may be an important determinant to the decisions
governing harvest and these are based on observations and experiences of the
harvesters who live close to the trees. In this context it is interesting that our results
indicate that when the method of harvest is intensive as in the case of Kotagiri and
Gudalur where harvesters use incisions, trees were more likely to get harvested than
those in Coonoor, where only resin naturally produced on the tree is removed. In the
case of harvest of an oleo resin from Copaifera sp, environmental and morphological
factors restricted productivity and not all trees produced amounts of oleo resin with
similar regularity (Newton et al, 2010). However frequency of tapping, and size of the
tree were shown to be significant predictors of resin production in Boswellia
papyrifera in dryland forests of Africa (Eshete et al, 2011). This is likely to explain
21
some of the variation in our results. Size of the tree alone does not influence whether
the tree will get harvested or not (Table2.6.), but size of the tree matters when the
quantity of resin is taken into account; significantly larger volumes of resin were
harvested from larger trees. This is the strategy that the resin harvesters of Coonoor
employed, to wait for the tree to grow big and yield resin naturally. While Kotagiri
and Gudalur harvesters tapped more trees, they did not actually obtain more resin at
the stand level than did harvesters in Coonoor (Table 1). Although our models showed
that at the individual level there was no significant difference in resin yield/tree across
regions, this may be a result of the low sample size of trees harvested in Coonoor
within the two year study period (Table 1).
The explanation for our findings that trees with green flush were significantly
more likely to be harvested than those with red flush is not clear, since red flush
apparently does not require more resources and is a protection mechanism against
herbivores by keeping young leaves virtually devoid of nutritive value (Dominy et al
2013). This merits further investigation and has also been discussed further in Chapter
3.
Effects of harvest on vital rates
The trade-offs between growth, reproduction and defense has been a subject of
much interest to evolutionary biologists. When resources like resin are removed from
trees, the stress caused may result in poorer reproductive output and changes in their
biology (Cunningham & Mbenkum 1998; Rjikers, 2006). In the case of resin
extraction from Boswellia papyrifera Rjikers et al (2006) showed that trees that were
subjected to experimental tapping produced fewer flowers, fruits and seeds. In their
study on resin producing species Boswellia papyrifera, Groenendijk et al (2011),
showed that poor regeneration in their study species was unlikely due to harvesting
22
and was driven by fire, grazing and beetle attacks. Eshete et al (2011) showed that
seeds from trees that were untapped for resin in Boswellia papyrifera had a
significantly higher percentage of germination that the tapped trees. On the other
hand, Baldauf et al (2014), in their study on latex extraction (which includes bark
defoliation), show that these harvests have a significant positive effect on fruit
production of their study species in Brazil. Our results show that resin harvest did not
have any significant negative effect on the growth of the trees, and that harvested
trees had significantly higher fruit production and germination than non-harvested
trees (Table.2.6). One explanation could be that trees that are able to produce resin
have more resources than those that do not produce resin, and therefore have higher
levels of fruit production and produce seeds that have higher probability of
germination. Zuidema et al. (2009) and Jansen et al. (2011) have shown that for
populations of some trees and palms, vital rates of some individuals are significantly
greater than those of others, and that these ‘super performers’ therefore contribute
disproportionately to population growth. This could also be the case with C. strictum
and merits further research.
Implications for sustainable management
Our research suggests good potential for the sustainable harvest of C. strictum.
Resin harvest as practiced across the three study regions, and including both tapping
and opportunistic harvest of resin naturally produced, does not appear to have
negative effects on growth, fruit production or germination. However, although our
models showed no significant effects of harvest on mortality, it is possible that this
may be due to sample size and the relatively short duration (two years) of our study.
It is noteworthy that all six of the trees that died in our study were harvested, and that
other authors have reported (but not tested) that harvested trees appear to fall easily in
23
the wind (pers comm – resin harvesters). Even if harvest leads to early mortality,
management that includes protecting and out planting saplings, could alleviate
potential negative effects. The potential for out planting efforts exists as local
organizations in the region already grow C. strictum seedlings for distribution to
communities.
Our study was limited in that it was not possible to test the effects of different
harvest practices within the same region. Thus comparisons between tapping with
incisions (Kotagiri and Gudalur) and natural harvest (Coonoor) are confounded by
other potential differences between these regions. These kinds of tests would be
possible at field stations and could yield further insight on optimal strategies for
harvest. Ultimately though, decisions about harvesting practises are influenced by
social factors too (Chapter 4). Overall our two year study provides a baseline for a
lesser studied species, and a type of harvest (exudate harvest) for which very little is
known. In order to understand fully the dynamics of harvested species under different
abiotic and biotic conditions there is a need for long term monitoring of harvested
populations which could contribute to conservation aims for the species and the
ecosystem.
24
Table.2.1. Characteristic of 89 Canarium strictum trees in relation to harvest methods, percentage harvested, quantity or resin yielded and size
of tree across three regions of the Nilgiri Biosphere Reserve
Region Harvest method
Total
trees
observed
Trees
harvested
(%)
Trees
harvested
in both years
(%)
Total resin
quantity
harvested
in 2 years
(kgs)
Average
size of all
trees dbh
(cms) ±SD
Average
size of
harvested
trees dbh
(cms)±SD
Coonoor Natural 36 12 5 44 65 (±23.5) 77±22
Gudalur
Incision
(fire 30
years ago)
20 40 30 20 73(±23.6) 80±27
Kotagiri Incision 33 45 27 10 46(±16) 46±17
25
Table.2.2. Predictors of harvest status (yes/no) of C. strictum trees from a binomial
generalized linear mixed effects model.
Fixed effects
Estimate
SE
Z value
p-value
Intercept -14.4565 5.6567 -2.556 0.010599
Region Gudalura 1.3859 0.6867 2.018 0.043570
Region Kotagiria
2.4153 0.7108 3.398 0.000679
Log dbh1 3.2590 1.3155 2.477 0.013234
Flush colour redb
11.0031 6.2814 1.752 0.079827
Logdbh1:Fl.cl.red -2.8153 1.5165 -1.856 0.063389
Random effects SD
Site 1.324e-05
aAs compared to Coonoor region
bAs compared to flush colour green
Table.2.3. Predictors of quantity of resin harvested/tree in C. strictum trees over a two
year period, from a general linear mixed effects model with a negative binomial error
structure.
Fixed effects Estimate SE t value p-value
Intercept 0.582786 0.327410 1.780 0.075078
Total new incisions 0.034091 0.008248 4.133 3.57e-05
Logdbh1 0.254241 0.073203 3.473 0.000514
Random effects SD
site 1.255e-07
26
Table.2.4. Predictors of growth of C. strictum trees from a linear mixed effects
model.
Fixed effects Estimate Std Error t-value
(Intercept) -0.06944 0.06222 -1.12
Dbh (log transfrmd) 1.019602 0.014621 69.74
Region Gudalura
0.007031 0.0084 0.84
Region Kotagiria
0.003689 0.008764 0.43
Total resin quantity (log transformed) 0.000103 0.00064 0.16
Canopy openb
-0.00655 0.011122 -0.59
Canopy partialb
0.00027 0.01119 0.02
Flush redc
-0.05227 0.073534 0.71
Fruit level normald
0.003053 0.009742 0.31
Fruit level lowd
-0.00736 0.008383 -0.88
Logdbh:flcolred -0.01356 0.017819 -0.76
Random effect SD
Site 0.0 a Compared to Coonoor.
bAs compared to closed canopy
cAs compared to flush colour green
dAs compared to fruit level none
27
Table.2.5. Predictors of quantity of fruit produced in C. strictum trees from a
generalized linear mixed effects model with a negative binomial error structure.
Fixed effects Estimate SE Z-value p-value
Intercept -6.1152 1.6709 -3.66 0.000252
Log of dbh 2.5407 0.3919 6.483 8.98e -11
Harvested treesa
0.7377 0.2966 2.487 0.012867
Flush colour redb
1.0962 0.3316 3.305 0.000949
Random effects SD
site 0.00E+00 aAs compared to not harvested trees
bAs compared to flush colour green
Table.2.6. Predictors of the probability of C. strictum seed germination from a
binomial linear mixed effects model.
Fixed effects Estimate SE Z-value p-value
Intercept -5.4836 2.9640 -1.850 0.0643
Log of dbh 1.3515 0.7073 1.911 0.0560
Harvested treesa
0.9794 0.4089 2.395 0.0166
Random effects SD
tree.id: site 5.957e-01
site 5.631e-05 aAs compared to not harvested trees
28
Table.2.7. Summary table of predictors of resin harvest and effects of harvest on growth, germination, and fruit production in C. strictum
Predictor
variables
Response
variables
Size
Dbh
(cms)
Region
Gudalura
Region
Kotagiria
Harvest
(Y/N)
Total
resin
Harvested
(gms)
Canopy
openb
Canopy
Partialb
Fruit
level
Lowc
Fruit
level
Normalc
Flush
colour
Red d
Total
number
incisions
Total
times
harvest
Harvest status + * + + + *
Resin quantity + +
Growth + # + + + - + - + - #
Fruit production + + +
Germination - + aCompared to Coonoor region;
bCompared to close canopy;
cCompared to fruit level none;
d Compared to flush colour green
*size and flush colour are slightly correlated, the interaction between these terms has a negative effect on probability of a tree to get harvested
#size and flush colour are correlated, the interaction between these terms has a negative effect on overall growth
29
CHAPTER 3 - PHENOLOGICAL PATTERNS IN CANARIUM STRICTUM
ROXB. (BURSERACEAE), A RESIN HARVESTED SPECIES OF THE
NILGIRI BIOSPHERE RESERVE, WESTERN GHATS, INDIA
Introduction
For centuries human beings have used changes in plants to forecast seasons,
predict fruit yields, and determine animal migrations (Lantz et al, 2003). The field of
science dedicated to the study of seasonal biological activities and their responses to
environmental variation is phenology (Rathcyke et al, 1985). For plants, phenological
events and phases are an important part of their life cycle, from reproduction to
growth to maturing of fruit to leaf senescence. Phenological events have to be
synchronised as in the case of seed and pollen dispersal, which is vital to
reproduction, and is linked to the arrival of pollinators or seed predators/dispersers
(Van Schlaik et al, 1993). Many long term observation studies have shown that the
timing and intensity of these phenological events are sensitive to temperature, light,
precipitation and snowmelt dynamics (Chapman et al 2005; Alexander et al 2011;
Clinger et.al 2013). The links between phenology, and climate, and more recently
climate change exist at the global scale (Parmesan and Yohe, 2003; Root et al., 2003).
In the first attempt globally to correlate present day flowering records with flowering
records from museums and herbaria, Primack et. al. (2004) were able to demonstrate a
significant response of plant flowering time to changing spring temperatures over the
past century, specifically, that plants are flowering earlier because of warmer spring
temperatures.
Besides climate change, other anthropogenic factors affect the phenological
patterns in species. Periodic harvesting, grazing and fires have been shown to affect
the flowering, fruiting and production of new leaves in many harvested species the
30
world over (Ticktin, 2004; Gaoue et al, 2008; Schmidt. 2011; Mandle et al, 2013).
The harvest of non-timber forest products (NTFPs) such as fruit, bark, roots, and
resins, was shown as a significant contributor to declines in plant populations in many
tropical forests (Brummitt et al, 2010). In a review paper on non timber forest
produce harvesting, Brites and Morsello (2012) showed that 67% of studies
evaluating the reproductive rates of harvested species reported a negative impact of
harvesting. In their study on the effect of tapping for frankincense from Boswellia
papyrifera, Rjikers et al (2006) show, that in heavily harvested trees, flower and fruit
production was limited and non-viable seeds were produced.
Plants produce leaves, flowers, fruits and seeds at particular times of the year
for important functions in their lifecycle (Rathcyke et al, 1985). In the case of
exudates like resin, which are produced by plants, they are important as defence for
injured tissues and to prevent attacks from insects and fungi (Langenheim, 2003).
Many plants in the tropics keep their young leaves virtually devoid of nutritive value
till they reach full size, also called the delayed greening strategy, in order to protect
them from herbivores (Kursar and Coley, 1992; Van Schlaik 1993; Dominy 2013).
The anthocyanin pigments present in young leaves are acidic therefore unpalatable to
herbivores (Karageorgou et al, 2006). These pigments cause the leaves to look red and
thereby making them invisible to most invertebrate herbivores, who lack a visual
receptor for red (Dominy, 2013).
While rates of production (of leaf, flower, fruits and seeds) have been studied
in relation to harvest pressure, lesser number of studies have been undertaken on
effects of harvesting practises on the timing of various phenological events (for
example Baldauf, 2014). The first ecological study on black dammar (Canarium
strictum Roxb., Burseraceae), an important resin-producing medicinal species in the
31
Western Ghats in India showed variations in population structure based on harvest
types (Varghese and Ticktin, 2008). Several authors have expressed concerns that
populations of C. strictum are disappearing due to tapping practices (Kannan, 1992 ;
Augustine and Krishnan, 2006). Fruits of C. strictum are reported to be dispersed by
large birds (Ganesh and Davidar, 2001), including some species of endangered
hornbills (Bucerotidae) (Kannan, 1992). Canarium fruits are the second most
important species, next to figs, in the diet of more than 16 species of hornbills
(Kitamura, 2011).
Our study looks at the phenology C. strictum Roxb. and provides details of the
phenology (flush, flower and fruit timings) and life history of C. strictum across three
regions of the Nilgiri Biosphere Reserve (NBR). We further explore differences in
phenology between harvested and not harvested C. strictum trees across the regions.
We do this by asking the following questions 1) What is the timing of flush, flower
and fruit events and does this vary across regions; 2) How do these events vary
between harvested and not harvested individuals; 3) What intraspecific variations
exist in the flush colour of C. strictum and what factors can explain this variation?; 4)
What animals are dependent on the flush, fruit and flower of the tree?
Materials and Methods
Study site
The Nilgiri Biosphere Reserve (NBR) is part of the Western Ghats chain of
mountains of the Indian peninsula, and lies between 100 45’N to 12
0 N and 76
0 E to
770 15’ E with a total area of 5520 km
2 spread across the three southern states of
Karnataka, Kerala and Tamil Nadu (Prabhakar, 1994). Altitude varies from 250m to
2650m, and at least four of the major rivers of south India originate in this region - the
Bhavani, Moyar, Kabini and Chaliyar rivers. The region is home to endemic and
32
endangered fauna like the Lion Tailed Macaque (Macaca silenus), Bengal Tiger
(Panthera tigris), King Cobra(Ophiophagus Hannah), Asiatic Elephant (Elephas
maximus), Great Indian Pied Hornbill (Buceros bicornis) (Daniels, 1995). The floral
diversity is unique to the region especially in the forests of the high elevation which
have several species and genera that are endemic and endangered (Keystone, 2007).
The range of topography and climate has resulted in sharp gradients of vegetation
composition, ranging from thorny scrub forest dominating the north-eastern region
and intergrading westwards into dry and moist deciduous forests and wet evergreen
forests towards the western parts of the reserve (Prabhakar, 1994).
Study species
Canarium strictum, Roxb. is a large tree, buttressed, up to 30 m tall with a
clear bole trunk, brownish bark, with terete branchlets which are ferruginous
tomentose. Leaves are compound, imparipinnate, alternate, spiral and clustered at
twig ends upto 40 cm in length. Leaflets are in 3-9 pairs with odd one at the apex;
increasing in size towards apex. The flowers are polygamous and the fruit is an
ellipsoid drupe, upto 5 cm long with one to three seeds enclosed within its woody
endocarp. It is an occasional canopy tree in the evergreen forests up to 1300 m and
reported from the Western and Eastern Ghats, parts of North East India and Myanmar
(Gamble 1915; Ravikumar & Ved 2000; Shashidharan, 2006). C. strictum has not yet
been assessed for it conservation status, though at the regional level it is listed as a
species of conservation concern, one among the 195 medicinal plants identified for
conservation action (Ravikumar et al, 2000).
Vegetation, rainfall and resin harvest practices in study sites
Our study sites were located in three regions Coonoor, Kotagiri and Gudalur,
(Appendix A) in semi evergreen forest types where Mesua ferrea, Elaeocarpus spp.,
33
Schelichera oleosa, and Persea macarantha were dominant tree species. In Coonoor
and Kotagiri, two sites each were selected based on the availability of a minimum of
10 adult C. strictum trees (above 25cm dbh) with an equal number of harvested and
not harvested trees. At Gudalur, we chose only one site since we were able to find 20
trees with an equal number of harvested and not harvested individuals. The trees in
Gudalur were located within an established coffee plantation bordering the evergreen
forests. Gudalur gets the bulk of its monsoon from the southwest monsoons which
come between June to September (Figure.3.1), while both Coonoor and Kotagiri get
their rainfall mostly during the north east monsoon which is between October and
December (Figure.3.1).
Three distinct methods of resin harvest: tapping, tapping with fire and
collection from natural fissures on the bark are practised in the NBR (Varghese and
Ticktin, 2008). In the Coonoor region resin harvest is more opportunistic and resin is
collected from natural deposits on the bark of the tree. During our field study we
observed that some harvesters in Coonoor have started to make incisions on the bark
of the tree. In Kotagiri, resin is harvested by making incisions on the bark of the tree.
In the Gudalur region it was the practise, 30 years ago, to use fire to prepare the tree
after which the tree was incised to yield resin. The use of fire has been discontinued
owing to forest laws preventing the use of fire and only incisions are made on the tree
bark for harvesting resin.
Phenology and resin harvest observations
Canarium strictum populations were located inside forest areas that were
accessible by four wheel drive jeeps and then walking for another 30min to three
hours. We conducted observations every fortnight over a period of 24 months, on
presence or absence of leaf, flush (colour), flower, and fruit. We monitored the trees
34
for presence or absence of fresh incisions for resin harvest. We also recorded the
number of times resin was harvested from each tree and estimated quantity harvested.
For the Coonoor region resin harvest was identified by signs of damage to the bark.
Field assistants from local villages, who were also resin harvesters, were able to tell
us how much resin was harvested each time. In addition to this research assistants
accompanied harvesters on resin collection visits to the forest and carried with them a
standard hand held weighing scale to get accurate measurements of quantity.
Observations of animals found eating fruit or leaves, building nests or visiting the
flowers were also recorded. The entire sample included 89 adult trees, 45 of which
were never once harvested for resin during the entire study period and 44 trees that
were harvested regularly (Table.3.1.).
To identify phenological patterns we calculated the percentage of trees that
were in flush, flower and fruit each fortnight and compared across regions; between
harvested and not harvested trees, across years, and against resin quantities harvested.
Measurements of diameter at breast height (dbh) were recorded for all individuals at
six month intervals. We tested for predictors of flush colour (green versus red) using a
binomial generalized linear mixed model, where flush colour was the response
variable; region, dbh and openness of the canopy were independent variables and site
was a random factor. We reduced the full models in a backwards stepwise process
sequentially removing the least significant fixed effect term in the model and testing
for significance with log likelihood ratio tests (Zuur et al. 2009). All analyses were
completed in R.2.13.1 (R Development Core Team 2011) using the lmer function in
the lme4 package (Bates et al 2011)
35
Results
There were variations in flush characteristics, resin harvests, fruiting and
flowering in C. strictum adult trees across time and region (Table.3.1.). Nearly 50% of
the trees that were selected for the study were harvested for resin in the recent past
and depending on the region, up to 15-61% of trees were harvested successively over
the two year period (Table.3.1). The percentage of harvested trees was lowest in
Coonoor and highest in Kotagiri (Table.3.1). Between 15-54% of the trees in our
study sites produced fruit in successive years and up to 40% of the trees flowered but
did not fruit, depending on the regions.
Phenological patterns in Canarium strictum
Canarium strictum trees begin to produce young leaves or flush towards the
end of December, going into January sometimes continuing to March (Figure.3.2.,
3.3.). Trees or individual branches re-sprout quickly when they have been damaged,
and flush may also be produced during that time. Throughout the year flush would be
present in more than 80% of the trees especially in two regions, Kotagiri and
Coonoor. During the study period we recorded damage to trees due to impact of
falling neighboring trees. Trees in Gudalur region, owing to their location in a coffee
plantation, with lesser neighboring trees, seldom, faced this natural disturbance and as
a result flushing was observed to be less (Figure.3.2., 3.3.). Peak flush period was
slightly different for all three regions but similar for sites within a region. Most trees
in Gudalur region started to produce new flush in December and January, whereas
Coonoor and Kotagiri had a slightly delayed flush period from January to March.
Finally at no point in the year was a tree leaf less and during peak flush times the
entire tree had only new young leaves. C. strictum leaves were observed to be present
in the forest litter all through the year
36
The flowering period was relatively short in C. strictum trees and flowers
persisted not more than 10 days. No flowers were observed fallen on the forest floor.
Maximum percentage of trees in flower was observed in February, March and April at
all the sites (Figure.3.2., 3.4.). Extended flowering periods were observed in site 2 in
Coonoor region and site 1 in Kotagiri region (Figure.3.2., 3.4.). All flowering
occurred before the onset of the rain period which begins in June (Figure.3.1).
Flowers of C. strictum are very fragrant and while some of the trees flowered
gregariously others produced flowers only on select branches.
Fruits of the C. strictum tree were very prominent and stood out over the
canopy when they were full grown and mature. Fruiting began new in the months of
April and no new fruits were observed on the canopy after July. Fruits were bluish
green in colour and matured by July at which time they turn purplish blue and were
visible even from a distance. Fruits persisted on the trees till about November
(Figure.3.2., 3.5.). At any point of time in the forest C. strictum fruits were available
on any one tree at all of the sites (Figure.3.2, 3.5.). In one year in Coonoor young
fruits were found lying on the forest floor, aborted at an early stage, in the subsequent
year that particular tree dried up and died.
Overall the presence of flush on the tree was followed closely by flowering
and in turn by fruiting (Figure.3.2). There were periods when phenological conditions
overlapped; most often with flush and flower timings and in some rare cases fruiting
overlapped with flush but this was also because fruits persisted from the previous
year. There were times when fruit, flower and flush timing overlapped especially in
Kotagiri region (Figure.3.2). All trees were observed to be in flower once during the
period of study.
37
Variation in phenology in relation to harvest of resin
Harvested trees flowered more frequently than non-harvested trees
(Figure.3.4.). Harvested trees in all three regions showed two flowering periods,
January to March and the other after October. Only in one case, in the Coonoor
region, not-harvested trees also flower after October (Figure.3.2, 3.4.). In terms of the
timing of the flush (Figure.3.3.) and fruit (Figure.3.4.) there were no differences
between harvested and not harvested trees.
Overall resin was harvested every month in all the three regions (Figure.3.7).
There were no clear peaks except in the Coonoor region where the harvest was more
opportunistic and peaked before the flowering period, February (Figure.3.4.) and after
the rain period which ends in November (Figure.3.1.). In the Gudalur and Kotagiri it
is likely that resin is harvested based on market demand ( Chapter 4) and less on
biology of the tree.
Flush colour
Canarium strictum trees, were easily visible in the forest canopy as also the
saplings in the under storey, because of their distinct red velvety flush. Adult trees
flushed profusely lasting for a period of two weeks at which time no mature green
leaves were observed on the tree. In all the three regions we observed individual trees
produced two distinct flush colours, green and red. The probability for a tree to flush
green was significantly greater for bigger trees than small trees (Table.3.2,
Figure.3.7.). Openness of canopy, fruiting intensity (whether a tree fruited or not) and
region were not significant predictors of flush colour.
Animal interactions with Canarium strictum trees
Flush of the C. strictum trees was found partially eaten and lying on the forest
floor in Coonoor and Gudalur region (Table.3.3.). Local indigenous resin harvesters
38
informed us that the Langurs and Indian Giant Flying Squirrel (Petaurista
philippensis) forage on the young leaves. Interestingly in Coonoor there were huge
cavities in the trunk of C. strictum tree under which the young flush was found on the
forest floor. Flying squirrels have been observed living in these cavities and also were
reported by local harvesters.
The wood of the C. strictum tree seems to be easy to burrow and one tree in
Kotagiri was the nest of the Golden backed Woodpecker or Flameback (Dinopium
benghalense). The bird started to build its nest at the start of 2012 and till the end of
2013 there were three holes made along the trunk of tree.
Fruits of the C. strictum trees were eaten by a number of frugivores. In the
fruiting season, seeds with their fruit coats removed were found in abundance on the
forest floor. These were most likely fruits that have passed through the gut of a bird
and since the fruits are medium sized it could have only been a large bird. Local
informants told us that it was a pigeon (unidentified) and researchers in other forest
areas have observed doves eating the fruit (R.Ganesan per.com). In the Coonoor and
Gudalur regions local harvesters have seen the Great Pied Hornbill (Buceros bicornis
) feeding on the C. strictum fruits. One of the most common sights during the fruiting
season was the Malabar Giant Squirrel (Ratufa indica) feasting on the fruits in the
canopy. They would eat the fruit and drop the seeds; at any time on the forest floor
one could see seeds completely devoid of the fruit coat and also partially eaten fruits.
The seeds that fell on the ground were observed to be depredated on by rodents. Local
harvesters also report that the Flying Squirrel also feeds on the fruits of the C.
strictum.
39
Discussion
Our results from observational studies across two years in five sites located in
three regions of a biosphere reserve help in establishing a baseline for conservation on
a less studied and highly used species. Harvests of plant parts have been shown to
have significant impacts on the biology of the species and at multiple scales (Ticktin
2004). Our results show that C. strictum trees have phenological patterns that vary
with harvest of resin. We also observed variations in flush colour which have not been
recorded as yet (except in observations of resin harvesters-discussed in Chapter 4).
We discuss our results with a view to expanding the understanding on the ecology of
a harvested species and suggesting implications this has for conservation especially in
the light of climate change.
Flush an important phenological event
Production of young leaves or flush is an important event in the lifecycle of C.
strictum trees since it is one of the most frequent events recorded in our two year
observations in the NBR. While there were clear peaks when whole trees had only
new flush, but all through the year at least one branch per tree would have young
leaves. This raised an interesting question about investment that the trees were
making to produce new young leaves. According to one general estimate,
approximately one third of plant species in tropical forests delay the greening of their
leaves until full expansion (Coley and Kursar, 1996). This delayed greening strategy
is thought to provide young leaves with protection from herbivores and common in
shade tolerant species (Kursar and Coley 1992). This form of protection is derived
from keeping the young leaves devoid of nutrition and not by investment in expensive
physicochemical defences as previously thought (Dominy et al 2013). In the forests of
the NBR especially in the months of January to March many of the C. strictum trees
40
are distinct because of their bright red young leaves. Flush is also produced
throughout the year when the tree or branches begin to re-sprout. C. strictum is a
secondary species and young saplings shoot up through gaps in the canopy of the semi
evergreen forests. A recent study conducted across different forest types in the tropics
showed that anthocyanin pigments make the leaves acidic therefore unpalatable to
herbivores and because they are red in colour, they are invisible to most invertebrate
herbivores who lack a receptor for red (Dominy, 2013; Karageorgou and Manetas
2006). While it is interesting that the C. strictum trees may be doing this to protect
their young growing leaves, it would be interesting to know if this is timed with the
emergence of herbivores or if it varies with herbivore densities.
However, our results show that not all C. strictum trees produce red
flush and 10 – 55% of trees, depending on site, produced green coloured flush. This
feature of the trees has not been reported elsewhere. The occurrence of leaf colour
forms within a single plant population is of both ecological and evolutionary interest.
Intra species difference in colour of young leaves has been reported by Karageorgou
and Manetas (2006) in Quercus coccifera. Smith (1986) studied the distinct leaf
colour morphs in Byttneria aculeta and concluded that the green colour morph was
more heavily attacked by herbivores and this was related to the frequency of
occurrence of that morph in a particular habitat. Interestingly in the case of the
Quercus sp. photosynthetic efficiency was higher in the red coloured young leaves
and the young green leaves were more prone to herbivore attacks (Karageorgou and
Manetas, 2006). Our results indicate that there is a correlation between size of the tree
and colour of flush. As part of this study germination experiments were conducted in
shade house conditions with 490 seeds of C. strictum (Chapter 2), interestingly no
sapling was recorded with young green leaves. It can be that at some point in their
41
lifecycle, saplings with red flush grow into larger trees that produce green flush. We
observed that green flush trees flower gregariously and produce more resin and less
fruit (Chapter 2). It is possible that larger trees invest less in protection against
herbivores and more in resin production. Secondary dioecious species in tropical
evergreen forests of the Western Ghats have been observed transitioning from female
to male trees after they have established in the middle storey and after attaining a
certain girth class (R.Ganesan pers.com). C. strictum trees are reported to be
polygamous, and it is possible that the relative proportions of male and female flowers
on a tree shifts as the tree gets bigger. We were unable to test this because of the
difficulty of obtaining flowers from these very tall trees, but this warrants further
investigation.
Resin harvest and phenology
Wood exudates like resin are produced by the tree as a defence from fungal
and insect attacks (Langenheim, 2003). Plants allocate carbohydrates for resource
capture and growth, reproduction, storage and protection of captured resources,
therefore tapping of resin is likely to enhance the trade-offs between growth processes
and resin production (Rjikers, 2006). When timed properly, removal of resin can have
least impact on the vitality of the tree but this is often disregarded for short term
economic gains (Coppen, 1995). In Boswellia papyrifera tapping of resin is always
done in the leafless dry period making the synthesis of new resin dependant on stored
carbohydrates, and this result in low production of non viable seeds (Rjikers, 2006).
Depletion of carbohydrate reserves in other Boswellia serrata resulted in low fruiting
levels during the leafless period (Sunnichan et al 2005). Our results show that there
was no particular season when resin was harvested in Kotagiri and Gudalur regions
but in the case of Coonoor region there were peaks when more than 5000gms of resin
42
(Figure.3.6.) was harvested from a single tree. Interestingly this peak was just after
the monsoon rain of November (Figure.3.1) and before the flowering in February.
Since the harvesting in Coonoor region was not induced by incisions but took place
more opportunistically or when resin was observed on the tree, one could presume
that more resin is produced during these periods. With regard to flush and fruit
production, harvested and not harvested trees showed the same patterns and it was
only in the case of flowering that our results suggest a difference –in that more
harvested trees flowered in two periods. In their study on Himantanthus drasticus in
Brazil, Baldauf et al (2014) observed that flowering activity increased when
harvesting of bark exudate was 100%, though this did not guarantee an increase in
reproductive output. One particular tree in Gudalur region is worth mentioning which
flushed, produced mass flowers, fruits and also gave a kilogram of resin every three
months consistently for the two year observation period. This tree was not even
subjected to tapping and resin was flowing out of a natural break in its bark.
Flowering and fruiting in relation to climate
The Indian monsoons, estimated to be about 15-20million years old, are a
major annual climatic event (Sanyal2010) that can be expected to have shaped the life
history strategies of many plants and animals of the Indian subcontinent. Aravind et al
(2013) in their study for a common set of wind dispersed species show that mean
fruiting time is associated with arrival of the wet season, independent of region. High
solar radiation has been reported to trigger flowering events in many plants in the
tropics (Ashton, 1988). In the case of C. strictum trees of the NBR, flowering
occurred before the monsoons, independent of region, and was synchronously timed.
Mass flowering gives trees an adaptive advantage in attracting pollinators (Marquis
1988). In C. strictum trees we observed that the initiated flower buds would be
43
dormant till the young leaves expanded and turned green. Many species have been
shown to flower immediately after leaf flushing, especially in tropical dry forests
(Murali & Sukumar 1994; Gunarathne and Perera, 2014). C. strictum fruits were
abundant in some trees and persisted for up to eight months in all our regions. Fruits
were initiated in late March, matured by June and persisted in the mature state till
October-November.
The phenology of tropical woody plants is shaped by both abiotic and biotic
factors and irradiance and water stress have been shown to be the most influencing
abiotic factors (Van Schlaik 2011). Studies on phenology need to be designed to
understand how plants integrate abiotic and biotic factors added to the pressures from
harvest in the case of species that are harvested for their products. We would like to
emphasise that C. strictum is an important and less studied tree species of the Western
Ghats. The harvest of resin makes it a very important economic species and warrants
more studies to establish the impacts of harvesting on the biology of the species. The
tree is also found in natural habitats that are under pressure from changing climate, for
instance seasonal streams and springs. For this same reason investing in the long term
monitoring of the biology of the species is very crucial to understanding the linkages
to the environment.
In many tropical forests there seem to be few plants that regularly produce
edible fruits, seeds, flowers or leaves and these have been termed as “keystone plant
resources” (Terborgh, 1986). In the case of C. strictum previous studies have recorded
the importance of fruits from as a food source to rare birds and primates (Kannan,
1989; Kitamura 2011). In our study sites we report additional findings of young
leaves being foraged by primates and nesting spaces provided by the trees. Our
results clearly illustrate the presence of fruit and flush through the year, and as such
44
make this species a good candidate for a “keystone plant resource”. Although our
study was carried out over 24 months, longer term monitoring would shed more light
on inter annual variation and on the relationships between phenological patterns and
local climate. This would contribute greatly to the understanding and conservation of
this economically and ecologically important species.
45
Table.3.1. Characteristics of Canarium strictum trees – Percent of trees in different conditions during study period
Region Site
Total count of
trees observed
for 2 years
Trees with
red flush (%)
Trees with
green
flush(%)
Trees
harvested
successively
over two
years(%)
Trees
fruiting
successively
over two
years (%)
Trees that
flowered but
did not fruit
in successive
years (%)
Coonoor Coo1 20 35 55 15 15 25
Coonoor Coo2 16 56 44 19 43 6
Gudalur Gud1 20 55 45 35 30 40
Kotagiri Kot1 13 62 38 61 54 8
Kotagiri Kot2 20 90 10 25 30 0
46
Table.3.2. Effects of size as determined by diameter at breast height, openness of canopy and location on the colour of flush in Canarium
strictum trees from a binomial generalized linear mixed effects model.
Fixed effects
Estimate
SE
Z value
p-value
Intercept 8.8204 3.1791 2.775 0.0553
logdbh -2.1710 0.7557 -2.873 0.00407
canopyopen 0.6865 0.8480 0.810 0.41819
canopypartial 0.1863 0.8625 0.216 0.82898
Random effects SD
site:region 0.000
region 0.348
47
Table.3.3. Observations of animals dependant on the Canarium strictum tree, flush, flower or fruit
Region Site Frugivores mentioned/ observed consuming C.
strictum fruits
Animals or birds using tree
for nest
Animals observed eating flush
Coonoor Coo1 Unidentified species of pigeon, Malabar Giant
squirrel(Ratufa indica), Indian Giant Flying
squirrel (Petaurista philippensis),
Indian Giant Flying squirrel
(Petaurista philippensis)
Gray Langurs (Semnopithecus
sp.)
Coonoor Coo2 Unidentified species of pigeon, Malabar Giant
squirrel(Ratufa indica), Indian Giant Flying
squirrel (Petaurista philippensis),
Indian Giant Flying squirrel
(Petaurista philippensis)
Nilgiri Langur (Trachypithecus
johnii)
Gudalur Gud1 Unidentified species of pigeon, Malabar Giant
squirrel(Ratufa indica),Great Indian Hornbill
(Buceros bicornis)
None Nilgiri Langur (Trachypithecus
johnii)
Kotagiri Kot1 Unidentified species of pigeon, Malabar Giant
squirrel(Ratufa indica),
Golden backed woodpecker
or Black rumped flameback
(Dinopium benghalense )
None
Kotagiri Kot2 Unidentified species of pigeon, Malabar Giant
squirrel(Ratufa indica),
None None
48
Figure. 3.1. Rainfall (mm) over 2011-12 in three study regions located in the Nilgiris district of the Nilgiri Biosphere Reserve
49
Figure.3.2 Phenology of Canarium strictum trees located in 5 sites in 3 regions of the NBR across a two year period
50
Figure.3.3. Percent of harvested and not harvested trees in flush across three regions of the NBR in 2012-13
51
Figure.3.4. Percent of harvested and not harvested trees in flower across three regions of the NBR in 2012-13
52
Figure.3.5. Percent of harvested and not harvested trees in fruit across three regions of the NBR in 2012-13
53
Figure.3.6. Total amount of resin harvested across two years from Canarium strictum trees in three regions across the NBR
54
Figure.3.7. Distribution of Canarium strictum trees with green and red flush in relation to diameter at breast height
55
CHAPTER 4. TRADITIONAL ECOLOGICAL KNOWLEDGE OF RESIN
GATHERERS OF THE NILGIRI BIOSPHERE RESERVE, WESTERN
GHATS, INDIA
Introduction
Traditional ecological knowledge (TEK) is a body of knowledge that has been
handed down over many generations through an oral tradition and comprises a way of
life in terms of practice, knowledge and belief (Berkes 1999). TEK helps indigenous
communities survive in the environment around them and define their cultural beliefs
and practices, for instance from the tradition of sacred groves in India (Gadgil 1992).
The idea that TEK is capable of adapting to both external changes and internal
pressures has been a mainstay of human ecology for some time (Berkes et al 2000).
Yet by analyzing change primarily in terms of lost knowledge, the dynamic nature of
TEK, and causes for TEK loss, effects these may have on the capacity of communities
to generate, transmit and apply TEK is given little emphasis (Gómez-Baggethun et al
2013). The young people in indigenous communities are important role players in the
practice and sustenance of TEK and few studies have documented the knowledge that
the young have in relation to forest gathering (Uprety et al 2012; Demps 2012).
Gathering products from the wild requires skill and as in the case of many
activities like scaling rocks to collect honey, setting traps for hunting, fishing etc. The
skill is linked closely to knowledge about the environment, behavior of the animal,
seasonal changes, phenology etc. Use of TEK has become more common in
conservation planning and resource assessment for reasons of efficiency, additionality
and community participation (Berkes et al, 2000; Sheil et al 2004; Rist et al 2010;
Sundaram et al, 2012) Often this is interpreted as using local people to undertake field
56
work to reduce the costs of data collection and less recognition is given to the TEK
which is an integral part of traditional resource management (Moller 2004).
The practical application of TEK and knowledge of the consequences of
management that TEK brings is of great value for conservation aims (Rist et al, 2010).
In recent years, fuzzy cognitive modeling has emerged as a method to document
traditional ecological knowledge especially with indigenous users of natural resources
(Berkes, 2008). In many communities decision making is guided by their TEK which
deals with complexity through rules of thumb and indicators which are used to
simplify questions about natural resource use, consistent with fuzzy logic thinking
(Berkes 2009). Fuzzy logic models allow management of complex non-linear
systems traditionally with industrial process and more recently with ecological,
economic and geophysical systems by offering more opportunity to use human
judgment (Zadeh 2008). The knowledge used for decision making is not quantitative
but consists of fuzzy sets of information using rules in the form ‘IF a certain situation
occurs, THEN a known outcome is likely and can have several conditions linked by
AND, OR, NOT (Mackinson 2001; Uricchio 2004). Such approaches have been used
as a tool in documenting fisher knowledge since it allows description of their
ecological and technological knowledge (Grant & Berkes 2007). This approach has
also been used in understanding community perceptions on conservation issues like
illegal bush-meat consumption in the Serengeti National Park, Tanzania (Nyaki,
2013).
The complementarity between traditional and scientific sources of information
has given more room for the use of TEK in ecological research (Moller et al, 2004;
Setty et al, 2008; Rist et al 2010; Sundaram et al 2012). TEK can not only add to
scientific knowledge but present a different picture of reality making it of great value
57
especially in the case of lesser studied species. TEK can provide the much needed
historical baseline which is often lacking in short term studies. Therefore we studied
the TEK of resin harvest, a traditional practice of the indigenous communities with a
view to document the decision making process and understand changes that are taking
place to the practice. Very often harvesting practices are documented with a view to
suggest improvements to methods and increase yields, there remains little discussion
on the ecological knowledge that is generated as a result of these practices.
Our study was undertaken in the Nilgiri Biosphere Reserve (NBR), part of the
Western Ghats hotspot region which has a density of 267 people/sq. kms of area, the
highest reported among the 25 biodiversity hotspots of the world (Cincotta et al
2000). An estimated 20 distinct indigenous groups live in the NBR and depend on the
forest products for their livelihood needs (Keystone Foundation, 2007). Upto 40% of
family income of the indigenous people in some areas of the reserve is derived from
sale of forest products (Pain 2009). Forest products like honey, resin, medicinal
plants, fruits, and leaves are gathered for local consumption and sale (Keystone
Foundation, 2007).
In our study we explore the knowledge of harvesting a locally important forest
produce - resin from the tree, Canarium strictum, Roxb. (Burseraceae). We use a
fuzzy logic approach to examine if and how ecological and management factors and
their interrelationships are used to make decisions about harvest. We present the
context of resin harvest in the NBR and then ask: 1) what factors are perceived by
forest produce harvesters as important to determine quality of resin and availability of
resin trees in the forest? 2) How are practices of resin harvest changing today?
We expected that knowledge about resin harvests would vary across regions
because of the different harvesting practices involved. We expected harvesters of
58
resin to have detailed knowledge on the factors that affect resin quality and that these
would include both biotic and abiotic factors. Finally we expected that TEK of resin
harvesters can be useful for integrating for conservation and wild product
management decisions in order to achieve conservation goals in landscapes where
people and biodiversity co-exist.
Materials & Methods
Region
The Nilgiri Biosphere Reserve (NBR) is part of the Western and Eastern Ghats
chain of mountains of the Indian peninsula, and lies between 100 45’N to 12
0 N and
760 E to 77
0 15’ E with a total area of 5520 km
2 spread across the three southern states
of Karnataka, Kerala and Tamil Nadu (Prabhakar, 1994). Altitude varies from 250m
to 2650m, and at least four of the major rivers of south India originate in this region -
the Bhavani, Moyar, Kabini and Chaliyar rivers. The region is home to endemic and
endangered fauna like the Lion Tailed Macaque (Macaca silenus), Bengal Tiger
(Panthera tigris), King Cobra (Ophiophagus Hannah), Asiatic Elephant (Elephas
maximus), Great Indian Pied Hornbill (Buceros bicornis) (Daniels, 1995). The floral
diversity especially in the forests of the high elevation has several species and genera
that are endemic and endangered (Keystone, 2007). The range of topography and
climate has resulted in sharp gradients of vegetation composition, ranging from thorny
scrub forest dominating the north-eastern region and intergrading westwards into dry
and moist deciduous forests and wet evergreen forests towards the western parts
(Prabhakar, 1994).
59
People
Amongst the more than 20 distinct indigenous groups in the NBR, we
interacted with five of them: the Cholanayaka, Irula, Kattunayaka, Kurumba, and
Soliga (Table.4.1.). The Cholanayaka, Kattunayaka and Kurumba continue to practice
their hunter gatherer way of life and are known for their honey hunting skills and
collection of resin among other forest products. The Irula and Soliga additionally
practice shifting cultivation. All five communities have strong links with the forests
and live in close proximity to it (Appendix A). In an inventory of the forest plants of
the NBR, knowledge of more than 300 species of plants are documented for each
community (Keystone, 2006, 2008).
Resin tree
C. strictum, is an important and heavily harvested tree, which produces the
resin known as ‘black dammar’. C. strictum is a semi evergreen tree found in the wild,
rarely in cultivation and is distributed unevenly along the Western Ghats and other
parts of India (Shashidharan, 2006). Little is known about C. strictum’s conservation
status nationally or globally, but regionally C. strictum has been reported to be a
species of conservation concern because of the high pressure from harvest of resin
(Ravikumar and Ved 2000).
In India, resin harvesting is an ancient practise that has been recorded in
ancient texts, and in the Western Ghats too resin is an important part of rituals and has
been harvested for a long time. Resin from C. strictum is harvested for local
consumption as well as for sale and the species is subjected to different types of
harvest methods and frequencies across the region (Varghese & Ticktin 2008).
Typically in the Kotagiri region, resin is either collected opportunistically from trees
where it has collected naturally, or by making incisions and returning to collect resin
60
after a period of time. In the case of resin harvest from Nilambur region, the common
practise is to set fire at the base of the tree before making incisions.
Methods
Focus group discussions were held in 2012-13, in nine villages across five
regions where C. strictum is harvested in the NBR (Table.4.1). Villages were selected
based on their proximity to the forests where the resin trees were present and on their
harvest methods (Appendix A).
Introductory meetings were held in all the nine villages to introduce the
research questions and to request the community’s willingness to participate in the
discussions. Focus group discussions, as well as informal conversations were held in
the language of the state: Tamil for Tamil Nadu, Malayalam for Kerala and Kannada
for Karnataka. We used the help of an interpreter for discussions held in Kannada. All
the communities have their distinct languages but are also comfortable to speak in the
state languages. We obtained informed consent from interviewees and Human
Subjects Review Board exemption (Appendix D).
Focus group (7-13 participants) discussions to understand the traditional
knowledge of resin harvest were organised in three sessions over time in each of the
nine villages. Each discussion session was planned for one hour, and questions and
topics discussed were as following: Session 1) Main topic: Resin quality – We start
with a general discussion on resin harvest practises –prevalence and legal issues. We
then discussed tools used for harvest, how many grades of resin are collected, what is
the resin used for (is there any animal or plant that needs the resin), which is the
season for resin collection and preparation of the tree, and why are there many grades
of resin? We also requested people, if they were willing, to show us resin that they
had harvested recently from the forests to give us an idea of the quality of the resin.
61
Session 2) Main topic: Number of resin trees in the forest. We start by asking how
often do the harvesters go to the forest for resin collection, how far away are the resin
trees, how much resin does one tree give, when does the tree give flower, fruit and
young leaves, what other animals and plants need the resin tree, what conditions are
important for there to be a high number of resin trees in the forest and if they have
seen any changes to the numbers of resin trees in the past ten years. Session 3) The
main points from earlier discussion are presented to the group. Each factor that was
mentioned in the first two sessions is represented on a large sheet of paper and
participants added more information if they felt anything was missing. Connecting
lines were drawn between factors by the participants to indicate relationships between
factors. Session three was organised at the level of the region (n=4) and harvesters
from each of the villages came together for this session. The information from this
session was later organised in sets using the ‘fuzzy logic’ principles for interpretation
(Berkes 2009) which relies on using the language variables ‘IF (situation) AND
(condition) THEN outcome’ (Mackinson 2001).
Resin of C. strictum was mostly harvested by the men of the community and
only in the case of the Cholanayaka people in the Nilambur region were women part
of the collection activity. Wage work is an important part of indigenous people’s daily
lives and attending meetings at the cost of their wages was not desirable. Most of the
meetings took place on holidays or at late evening sessions in the villages, after
people had returned from work. In some cases when it was not possible to meet on
holidays, compensatory wages were given for all who participated in meetings.
Informal discussions
As part of our ecological study on C. strictum harvest, we monitored 89 trees
in five locations fortnightly (Chapter 3). On all these monitoring field trips I was
62
accompanied by a minimum of two field assistants, one of whom was from the local
area and also a resin harvester.
Context of resin harvest in the NBR
Harvest legality, access, market demand, resin harvest practices and resin
quality vary across the five study regions (Table.4.1). Collection of resin is not
permitted for commercial sale by Tamil Nadu state forest authorities in Coonoor and
Kotagiri regions and therefore resin is used only for home consumption and local use.
In the regions of Nilambur which is in Kerala state and Chamrajnagar which is in the
state of Karnataka, resin collection is permitted and traded in the open market and
also through the government owned co-operative societies.
Access to the resin trees is mostly restricted to indigenous communities,
except in the case of the Kattunayaka village in Nilambur (Table.4.1) where the trees
were located in a privately owned coffee estate at which both indigenous and non-
indigenous people were employed for daily work. The resin trees in Chamrajnagar
were located within the protected area of a tiger sanctuary and only the Soliga people
had access to the site (Table.4.1).
In Coonoor and Kotagiri regions the trees were in reserve forest areas that are
under the control of the Forest Department (Table.4.1). The forests in Coonoor are
part of the ancestral lands of the Kurumba community people and the terrain is steep
and relatively inaccessible except to the Kurumbas. The trees in the forests of
Coonoor were found in the sacred groves of the Kurumbas. The Kotagiri forests were
relatively easy to access as there were motorable mud roads that provide access for
the many indigenous villages that are located in that region, even then no incident of
resin harvest by a non-indigenous person was reported from the past or observed in
63
the study period. The forests of Nilambur region are under reserve forests and have
relatively closed access because of the terrain and inaccessibility (Table.4.1).
Frequency and quantity of resin harvested varies highly across regions
(Chapter 2, Table.4.1). There are three main grades of resin in the markets and in
indigenous people’s homes (Appendix B). First grade resin consists of large blocks
which are highly priced and considered to be of best quality and can fetch a price of
INR 75 to 250. A block of resin that was nearly 12 inches long and 6 inches wide
weighs approximately 750-1000gms (per obs). This first grade of resin is found
mostly in Coonoor and Gudalur region of our study (Table.4.1). The second grade of
resin (Appendix B), smaller blocks, is sold for INR 40 to 150 depending on location
(Table.4.1). The third grade of resin is a powder form which is collected by scraping
the bark of the tree and is found available mostly in the Nilambur and Kotagiri
regions (Table.4.1). This powder form fetches anywhere between INR40-70
depending on the demand. In the Kotagiri region we observed that this powder form
of resin was offered to guests that were visiting the home of the resin harvester.
Through informal discussions with the harvesters we were able to assess an average
quantity of resin that was harvested in a year by an individual harvester.
Results
Factors perceived by indigenous harvesters to affect resin quality
The resin harvesters of Chamrajnagar are used to collecting only one type of
resin, the powder form with pieces of bark attached to it or grade three (Table.4.1,
4.2.a). In Chamrajnagar, factors relating to harvest method including tools and
incision, rainfall and specifically the character of the tree (size and resin producing or
not) are considered important in determining the resin quality (Table.4.2.). Indicator
64
species such as the insect ‘dhoopa nona’ (species unidentified; ‘dhoopa’ is the local
name for resin) are important in determining timing of harvest (Table.4.2.).
Harvesters from Coonoor collect only big blocks of resin or grade one resin
(Table.4.1, 4.3.) called ‘gatidhupa’. In Coonoor region where the harvest is done
without making incisions and is more opportunistic, time to harvest (waiting for resin
to mature), and character of the tree (size, and presence of resin droplets on bark or at
forks in the branches) are important factors that determine resin quality (Table.4.3.).
The harvesters also comment that, from experience, they know that only five out of a
hundred trees yield resin. Harvesters also mentioned that leaving the resin not
harvested if a bee colony was found on the tree, so as not to disturb the bees and since
the resin harvesters were also honey hunters (Table.4.3.).
Kotagiri harvesters mentioned at least two grades of resin (Table.4.1, 4.4.) that
is harvested from their forests. For the resin harvest in this region, factors relating to
character of the tree (stance, size, resin producing or not), harvest method (incision
height and depth, direction), season (harvest frequency, timing and incision making),
and biology (red and broad leaves) were important in determining the quality of the
resin (Table.4.4.). Harvesters insisted that making incisions was the only way to get
resin (Table.4.4.).
Nilambur harvesters reported three distinct grades of resin and indicated that
season (harvest and preparation of tree), harvest method (frequency and season) and
character of the tree (sloping and size) were important factors in determining resin
quality (Table.4.5.). No other indicators were mentioned by the harvesters of this
region.
The resin harvesters of Chamrajnagar and Kotagiri reported that there were
two kinds of resin trees, female (resin producing) and male (do not produce resin)
65
trees. Though the harvesters in Coonoor were clear that only a few trees yield resin,
they did not classify them as male or female trees. The harvesters in Nilambur
reiterated many times that all resin trees will yield resin.
Factors perceived by resin harvesters that allow for a high number of resin
trees
In our discussions about the resin trees the Soliga people of Chamrajnagar
were not able to comment on what factors allow for a high number of resin trees
because there were very few left in the forest according to them. The harvesters told
us of how they walked long distances these days to find even one resin producing tree
and resin harvesting was now more opportunistic. One elder in the group commented
that the people were too busy working on local estates for wage labour and did not
harvest resin as frequently as before. The harvesters informed us that when they see a
tree in the forest they would stop by it and harvest the resin (if there was some resin
left on the tree).
In the Nilambur when we asked about what factors allows for a high number
of resin trees in the forest, Cholanayaka people reported that there “are too many
trees in our forest and we need not worry about them”. The Kattunayaka people who
live in another forest in the same region, talked about the lack of trees and remember
how as young people they saw their parents carry large quantities of resin but today
there are only very young trees left in the forest. When we asked them what could
have happened, they clearly attributed the lack of trees to indiscriminate harvest
methods related to high demand and good prices which caused a lot of trees to fall.
The resin harvesters of Coonoor and Kotagiri considered different physical
and biological factors as influencing the high number of trees in their regions
(Table.4.6., 4.7.). In Coonoor region, the harvesters consider forest (evergreen and
66
large), water and associated species to be important factors. Many animals and birds
that disperse seeds were mentioned and also the fact that these trees prefer to be in
clusters was reported to be important (Table.4.6.). Harvesters of Kotagiri consider
availability of water, forest (evergreen and mountainous) and climate to be important
determinants to high numbers of resin trees (Table.4.7.). The role of seed dispersers
was considered favourable for regeneration though there was some concern about
predators like field rats (Table.4.7.) reducing the number of viable seeds. In these two
regions, none of the harvester groups who contributed to this question mentioned that
harvesting resin affects the number of resin trees in the forest.
Changes in resin harvest practises
The focus group discussions revealed that over the last decades and especially
over the last 10 years many changes have occurred in the traditional harvesting
practices (Table.4.8.). These changes appear to be influenced by laws of the state;
influence of neighbours, changes in respect for ancestral lands, increase in number of
harvesters, and market demand coupled with an overall decrease in the number of
productive trees.
In the case of the Kattunayaka people (Nilambur region) who live near a
coffee estate, they have stopped using fire to prepare their trees as was the tradition
since there are now very strict laws about fire use and the region is now highly
patrolled by the Forest Department. In the Coonoor region, harvest may be moving
towards incisions due to communication and exchanges about practises among
harvesters. For example, one harvester from a nearby village who is also a Kurumba
has started to make incisions on the trees in one of our study site. The harvesters who
accompanied us on field trips knew him and when we asked why this is happening,
they told us that he had family in the Kotagiri area and was trying out the incision
67
method that he saw the harvesters of Kotagiri use, since he believed that this would
increase the resin yield.
In Kotagiri and Nilambur regions the frequency of harvesting had
increased and this has affected resin quality. In the Nilambur region the elder
harvesters felt that the young were no longer respecting the traditional tenures and
would harvest any tree that came in their way. Kotagiri harvesters felt the demand for
resin has increased in the past years and this has lead to more frequent harvests. They
also feel the number of harvesters has increased whereas trees have not. At the same
time, the market may be driving changes in the opposite direction, as harvesters
observe the high price offered for high quality resin and are willing to improve the
quality of the resin (Table.4.3).
In the Chamrajnagar region the traditional methods are followed but harvesters
do not wait for the resin to get bigger and harvest it as soon as they see it. They
informed us that was also because they go less frequently to the forests these days and
were not comfortable explaining to the Forest Department officials each time what
they had gone for and what they had collected, so they maximise the harvest per trip
Discussion
Resin harvest is a prevalent practise amongst the indigenous people of the
NBR. When decisions about harvest of resin are taken factors that are perceived as
important to the harvesters are phenology, season, regeneration, region and
characteristics like size and stance. We compare these perceptions with the ecological
findings of our study (Chapter 2, Table 6) in the following section. Our results also
indicate that changes to resin harvest practises are effected by many social and
ecological factors which we discuss in the light of implications to knowledge
transmission and adaptation.
68
TEK of resin harvest in relation to ecological conditions
Our results illustrate detailed knowledge of indigenous communities in the
NBR related to the quality of resin and the factors that allow for a high number of
trees in the forest, although this varied across regions (Table.4.10.). In terms of resin
quality, harvesters in all four regions recognized tree size as a determinant. Of the
three regions where harvesters use incisions to tap resin, each recognized method as a
determinant of resin quality but each mentioned local variations to their methods. This
aspect, of specific methods, though reported to vary widely over space for a given
species (Ticktin Johns 2002; Ghirmire et al. 2004), remains understudied in terms of
the effects on the biology of the harvested species. In our ecological study (Chapter
2) we found no significant negative effects of harvest on vital rates of C. strictum and
this did not vary across regions. Therefore even though the harvesters have different
site specific methods this does not seem to affect the potential for sustainable
harvests.
In regions that use incisions, season, especially with reference to harvest
methods was important either in terms of preparation of the tree or in relation to the
harvest time. In the Philippines resin of Canarium luzonicum is harvested
commercially and although it can be collected throughout the year from the rain
forest, it is preferably harvested in the wet season when there is a greater resin flow
(Langenheim, 2003). Resin trees are hypothesized to produce more resin when they
are not growing, which in the tropics maybe less clear cut but excessive rain in the
monsoon and less sunlight could mean a low growing stage (Langenheim,2003).
Further research on how the timing of harvest affect. C. strictum yields and vital rates
would be valuable.
69
Interestingly the Soliga of Chamrajnagar knows that it is the right time to
harvest the resin when the insect which they called the ‘dhoopa nona’ which literally
translates to ‘resin insect’ has left the tree. We were not able to identify this insect.
These observations of the timing of plant or animal activities as indicators of
management are an important part of resource management practices elsewhere
(Moller 2004; Grant et al 2007).
Harvesters in the regions of Nilambur and Kotagiri discussed the conditions
associated with at least two grades of resin that was harvested and traded, as opposed
to only one grade which was discussed by harvesters in Charmrajnagar and Coonoor.
This may be a result of the fact that harvest takes place at more intense levels in these
regions - for Nilambur an estimated 100kgs is harvested per person annually whereas
Kotagiri harvesters only collect upto 20kgs(Table.4.1.). In addition to this the Kotagiri
harvesters mentioned that the number of harvesters has gone up and the number of
trees has decreased, suggesting that harvesters take whatever grade of resin they find
on the tree to out compete others. When this was mentioned one of the harvester in
the group disagreed, commenting that even though the resin with bark pieces or grade
two resin fetched a lower price in the market, according to him it was an indicator that
the harvester had deepened the incisions to ensure resin yield for the next visitor - e.g.
as a courtesy. This example highlights the importance of understanding when social
and ecological indicators meet.
The Irula harvesters of Kotagiri reported sex of the tree as a determinant of
resin quality, commenting that there are male and female trees but only female trees
yield resin. C. strictum is reported to have polygamous flowers (Shashidharan, 2006)
and our observations in the field suggest that some trees have many more male
flowers than female flowers. However, it is unknown whether the Irula categories for
70
male and female correspond to largely male or female trees in the botanical sense, and
would be an interesting avenue for future research. The Kotagiri harvesters’
perception that trees with red flush produce better quality resin also merits further
research. Red flush is often a defense against herbivores but does not require
additional resources (Dominy et al 2013) and it is unclear how it may relate to the
quality of resin produced.
In Kotagiri, (where incisions are used for tapping resin) and Coonoor (where
only naturally formed resin is collected) harvesters discussed both abiotic and biotic
factors as determinants to the presence of a high number of trees in the forest and the
factors were similar between regions (Table.45.). Harvesters in both regions discussed
factors associated with regeneration, including seed dispersal and seed predation.
Their observations of these processes point to the in-depth knowledge on this topic,
and contrasts with other studies that have shown that observations by forest produce
gatherers of the seedling regeneration process tends to be much less detailed than
other kinds of ecological knowledge (Setty et al. 2008).
Complementarity in science and traditional knowledge has been discussed in
human ecology writings, with many examples from fishers and temperate regions
(Berkes and Folke 1998; Turner 2000; Moller et al 2004; Grant & Berkes 2007). TEK
has also been documented with a view to integrate it with sustainable management of
natural resources (Moller, 2004; Sutherland, 2014). In more recent times especially
with the rising level of awareness on climate change and pollinator declines, globally
the need to integrate TEK is being recognised (Alexander et al 2009; Sutherland,
2014). Our results illustrate both how these two systems are complementary in the
case of C. strictum resin harvest (Table.4.11.). Many of the indicators reported by the
harvesters overlapped with the indicators that were tested in our ecological study
71
(Chapter 2, Table.4.11.) and still others like habitat quality, size, water availability
and plant-animal interactions which the harvesters reported could have only been a
product of much longer term observations. We also find that even though the aspects
of observation were common between TEK and ecological studies other factors that
were taken into consideration were different (Table.4.11.). In the case of phenology
and season, observations in TEK related to opportunities to improve or increase
harvest yield and less to the effects on the tree. Animal sightings were also indicators
to harvest timing. Various other studies have shown how TEK and ecological studies
compare in terms of qualitative and quantitative assessments among other factors
(Rist et al 2010; Sundaram et al 2012). In our context we also observed that harvesters
of one region were not necessarily aware of ecological context and harvest practises
of nearby regions and therefore lacked some of the insights that can come from
comparative research.
Changes and adaptation in TEK
There is a need to understand the conditions that support the generation of
TEK especially in the face of social-ecological changes that natural resource using
communities are facing today (Gómez-Baggethun et al, 2013). The capacity of
communities to respond and observe changes to the environment is an important part
of TEK (Berkes et al. 2011) and one that is key to the new basis of community based
conservation– one that does not rely so heavily on use but also brings in elements of
observing the pollinators or the fruigvores or dispersers that may not be directly of use
but are important to understanding the ecological processes that are undergoing shifts
in the face of large environmental changes.
Knowledge production is a learning process where the application of
knowledge to different scenarios produces outcomes that need to be evaluated and
72
adjusted as necessary (Grant and Berkes, 2007). Our results illustrate that harvesting
practises in the NBR are changing in different ways depending on the context. These
changes appear to be influenced by laws of the state, neighbours, changes in respect
for traditional tenure, pressure on the resource base, and market demand (Table.4.8.).
The effects of these factors on resource management practices have been widely
reported in the context of forest produce (Shackleton et al 2011). In some cases,
different forces appear to be pushing practices in different directions. For example, in
Kotagiri and Nilambur region, an increase in the number of harvesters and market
demand appears to be leading to new practises that are leading to lower quality resin
and are likely unsustainable. At the same time, a new market in Kotagiri that pays
better for high quality resin may be starting to cause shifts in management to obtain
higher quality of resin (Table4.4.).
One incident I observed during field work is illustrative of how traditional
practices are being adapted to changing climate conditions – although in this case
related to honey gathering. In 2013 one group of young people from Kotagiri from the
Irula community, who also gather resin, had gone out for gathering wild honey and
came back disappointed, since there was very little honey in the combs and the honey
was very high in moisture content ( honey with lower moisture content is an indicator
of mature honey and has longer shelf life and is preferred for sale fetching a higher
price (Keystone, 2007)). An elder from the same village then went out to the forest to
check what was happening and came back to report that that there was indeed
something wrong with the way the Naeri (Syzygium sp.) trees were flowering - some
of the branches had no flowers, while some had buds and still others had flowers. The
Naeri flower gregariously and this signals availability of bitter honey, a highly priced
commodity in the local market. There was much discussion about this in the village
73
and the elders came to the conclusion that the youth had not behaved in an
irresponsible manner by harvesting the honey before it was mature - but rather that
things were changing in the forests. In this case, the young people are keeping alive
the tradition of honey harvest because of the economic returns. And as they learn
about the changes to the environment the elders do step in to validate their
observations and dialogue with the young.
For TEK to be adaptive, it must be continually regenerated in response to
changing conditions, and it must continue to be transmitted (Moller, 2004). In our
discussions with the resin harvesters we observed that most were 30 years and above
and the oldest harvester was over 70 years. Across all the four regions harvesters
mentioned that “nobody taught us, we learnt by going to the forest”. Especially the
harvesters in Coonoor and Kotagiri mentioned that it was not from their parents that
they learnt but from uncles and friends with whom they went into the forest. When we
asked if they would teach these to their children the comments ranged from were- ‘our
children go to schools, where is the time?’; ‘there are too many elephants in the forest
these days’; ‘we don’t want out children to look to the forest for their livelihoods’.
However in one of our focus group discussions in Kotagiri, with the Irula and
Kurumba people, a group of young people assembled around us and they asked their
elders at the end of the meeting –“why don’t you teach us these things anymore”. The
elders just laughed it away. The young people then met me later and asked if we could
make charts with this information so that they could start to make written documents
about the methods that were practised in the past. When asked if they went to the
forest, they responded that they would go at least once a week even though they were
employed on estates for wage work. This was important they felt to not only gather
firewood but to keep their knowledge. The young men also said that they take their
74
children with them too. They also mentioned that often local medicinal plant traders
would ask them to get herbs from the forest and they would supply them for the
additional income. When asked how they recognised the plants, they confidently said
they know most of the plants and when they were in doubt they would consult with an
elder. Similar interest among youth in forest related activities has also been reported
in Nepal with wild food gathering practises (Uprety et al 2012) and in the case of Jenu
kurumba honey hunters of the Western Ghats, India (Demps 2012).
Our results illustrate some of the detailed knowledge that resin harvesters in
the NBR have and the indicators they use to assess resin quality and the availability of
resin trees in the forest. Community based monitoring programs that build on these
kinds of knowledge and observations can help ensure strategies that allow for both
use and conservation for the long-term while enabling communities to retain the
capacity to regenerate and transmit the TEK that is part of their identity.
75
Table.4.1. Details of harvester villages, communities, access, quality of resin and market price of resin across four regions in the NBR
Region State Number of
villages
interviewed
Indigenous
community
(also harvesters
of resin)
Access type Quality of
resin rating
~Annual
harvested
kgs/perso
n
Market Price
INR
Chamrajnagar Karnataka 2 Soliga Closed -protected area;
indigenous territory
Powder 5 40
Coonoor Tamil
Nadu
2 Kurumba Closed-terrain restrictive;
indigenous territory;
reserved forests
Big blocks 10 225-250
Kotagiri Tamil
Nadu
2 Irula
Kurumba
Partial-densely populated
villages in the area; trees
are in reserved forests
Small blocks 20 100-150
Nilambur Kerala 3 Cholanayaka
Kattunayaka 1*
Kattunayaka 2**
Closed-terrain restrictive;
indigenous territory;
reserved forests
Powder and
small blocks
100 40-100
*Live close to forests, collect less resin these days since number of trees in their forest has reduced drastically
**Live near a coffee plantation where there are resin trees. The resin in this area was of big blocks and access was of the open type since the
trees were located in the estate.
76
Table.4.2. Factors affecting resin quality as perceived by resin harvesters from Chamrajnagar region, arranged in fuzzy logic sets
Chamrajnagar
If tree is a resin producing tree (only some trees produce good resin)
If it is big (above 30cm dbh)
And incision can be made with axe
And incision has been left open for 3 months
Then resin can be harvested
And the resin will have bark pieces along with it
If the rain has come
Then the ‘dhoopa nona’ insect will be driven away
Then it is time for us to collect the resin
Conditions:
Incisions should be made only on one side not around the tree.
77
Table.4.3. Factors affecting resin quality as perceived by resin harvesters from Chamrajnagar region, arranged in fuzzy logic sets
Coonoor
If there are signs of resin forming on the tree at forks or cavities
And there are no honey combs on the tree (we would not harvest the resin so as not to disturb the bees-anyway the bees leave in 3 months-we
can always harvest the resin later)
Then the resin from this tree can be harvested
If the tree is bigger than 30cm dbh
If the resin has been allowed to mature for 3-6 months
Then we get big blocks of resin (gatidhupa)
Conditions:
Only a good resin tree will yield well - 5 out of 100 trees produce good resin.
78
Table.4.4. Factors affecting resin quality as perceived by resin harvesters from Kotagiri region, arranged in fuzzy logic sets
Kotagiri
If the tree is above 30cms (dbh)
And is a female tree (resin yielding trees -tested by making trial incisions on the tree- are called female trees.
Then incisions can be made 3 ft above the root and upto 10ft
If incision is made on the East facing side of the tree with the Sun’s rays reaching till the base of the tree
And the tree is sloping or has a tilted stance
Then incision should be made on the side facing the forest floor
And the incision is only as deep as the bark and is left undisturbed for 3 weeks
And the harvest is done in pre monsoon months
And the tree has produced many new red leaves
Then good quality of resin can be collected
If the incision is made on the West facing side of the tree
And is harvested in less than 2 weeks
Then resin of lesser quality is obtained
Condition:
Incisions can be deepened and prepared in the monsoons
Only if harvest is done with incisions will the tree produce more resin
Tree which have reddish and broad leaves will produce more resin
79
Table.4.5. Factors affecting resin quality as perceived by resin harvesters from Nilambur region, arranged in fuzzy logic sets
Nilambur
If it is monsoon
And tree is large
And tree is sloping toward one side
And fire is set on the sloping side
And the fire has been set in the summer
And it is the first resin flow
And resin is allowed to flow un harvested for 2 weeks (in summer the resin will be sticky and semi solid but in the monsoon it will be harder
with layers of resin)
Then we can get big blocks of resin (kaal pandham)
If the big blocks of resin have already been collected
And incisions have been be made on tree (upto the point that the flames have reached from the fire that was set in summer)
Then we get smaller blocks of resin (katta pandham)
If it is the subsequent summer after the fire was set
And new incisions are made on the tree
And resin has not been allowed to flow for 2 weeks or more
Then we get resin powder and scraped from the bark (podi pandham or thari podi)
80
Table.4.6. Factors affecting number of resin trees as perceived by resin harvesters from Coonoor region, arranged in fuzzy logic sets
Coonoor
If the forests are cool and evergreen
And the forests are large
And there are Suruli (Messua ferrea) trees close by
And running streams
Then there will be a good population of resin trees
Conditions:
Fruit that has been ingested and seeds dispersed by flying squirrel seem to germinate better.
The trees prefer to be in closed forests like groves, they are found close to each other.
Civets, giant squirrels, field rats, hornbills feed on the fruit/seed.
81
Table.4.7. Factors affecting number of resin trees as perceived by resin harvesters from Kotagiri region, arranged in fuzzy logic sets
Kotagiri
If there is water close by
And the forest is evergreen
And forest is in the mountains
Then there will be more number of trees
If there are storms these trees fall easily
And neighboring trees fall on them
Then there will be lesser standing trees
Other observations:
Regeneration is not a problem for this tree, fruits are eaten and dispersed by giant squirrel, flying squirrel, civets.
Some rodents (Chundelli) seem to eating the seeds on the forest floor and this may be affecting germination
82
Table.4.8. Recent changes in resin harvest methods across the four regions in the NBR
Area Harvester group Traditional harvest methods and tools Changes from traditional harvest methods
Chamrajnagar Soliga Incisions are made on the bark, 30cms above the
ground and resin is harvested using small axe or
knife.
The traditional practise is followed and resin is not
harvested for sale.
Coonoor Kurumba Trees are allowed to grow big and resin formed at
fissures on the bark or at branch forks are harvested
when matured and in big blocks. Blunt end of the
knife maybe used to detach the resin from the bark.
In one cluster of trees one of the young harvesters
has started to make incisions on the tree. But
majority of the harvesters follow the traditional
practise.
Kotagiri Irula + Kurumba Incisions are made on the bark above 50cms from
ground level. Incisions are made in circular patterns
and moved around so that old incisions heal. Knife
is used and a small axe in some cases.
Old method of harvest is followed but period of
waiting for the resin to mature has reduced from 3
months to two weeks. In one incident a group of
harvesters (Irula from Kotagiri) spent one month to
specially collect the resin in blocks from old trees
and brought 73kgs to the local market since they
had seen that the blocks of resin fetch double the
price they would normally get for their product.
Nilambur Cholanayaka Setting low grade fires to the base of the tree,
incising the bark with axe. Harvesting resin after it
has matured and forms big blocks
Traditional methods are followed but frequency of
collection has increased leading to poorer quality of
resin.
Kattunayaka
(residing near
estate)
Setting low grade fires to the base of the tree,
incising the bark with axe. Harvesting resin after it
has matured and forms big blocks. This was the
practise 20 years ago.
Fire is no longer used, only incisions are made to
the tree
83
Table.4.9. Summary of factors perceived by resin harvesters important to resin quality
Factors Chamrajnagar Coonoor Kotagiri Nilambur
Size of tree
Stance of the tree
Harvesting tool
Resin quality
Rain / Season
Animal indicator
Male and female tree
Flush colour
Table.4.10. Summary of factors perceived by resin harvesters important to number of trees.
Factors Chamrajnagar Coonoor Kotagiri Nilambur
Forest type
Forest size
Associated species
Water
Seed dispersers
Climate
Seed predators
84
Table.4.11. Comparison of perceptions in Traditional Ecological Knowledge and findings in Ecological studies in relation to aspects of resin
harvest and resin trees
Aspects of resin harvest
and resin trees
Traditional ecological knowledge Ecological Studies
Animal interactions Insects indicate time to harvest. Tree is a nesting site to
some animals. Young leaf and fruit are a source of food to
some animals
Tree as a nesting site and young leaf and fruit as food for animals
was observed
Fruit production Fruits were eaten by birds and rodents Harvested trees produced more fruit
Growth of tree Not described No significant factors affecting growth
Phenology Red flush indicated good quality resin tree and time to
harvest
Harvested trees show two periods of flowering. Trees that
produce green flush were more likely to be harvested than those
with red flush but only if they were bigger in size.
Regeneration Seed dispersers were important for seed germination. Seed
predation has a negative effect on regeneration.
Seeds from harvested trees showed higher germination rates.
Region Size of the forest; forest type; springs and streams
important; Presence of water; mountainous landscape
Trees of some regions were harvested more than others
Size of tree Larger trees were harvested Bigger trees yielded more resin; Bigger trees produced more fruit
Trees with green colour flush tended to be larger than those with
red colour flush; Seeds from bigger trees showed less
germination rates
Season Rain season yielded better quality of resin and trees were
prepared for harvest before the rains
Flowering occurs before the rain and resin harvest was spread
across the months. There was a peak in the post rain period
Tree stance Very important to make incisions; resin of high quality
produced by sloping trees
Not considered
85
CHAPTER 5. CONCLUSIONS
My dissertation examines the consequences of harvesting practises on the
ecology and phenology of a resin harvested species, Canarium strictum and explores
the traditional ecological knowledge (TEK) that harvesters have in relation to resin
harvesting. In this chapter I synthesise my findings from the previous chapters,
discuss the implications for managing harvests from the wild, and explore the
possibilities of integrating traditional ecological knowledge in community based
ecological monitoring programs that will enhance community based conservation. I
also describe the contributions of this research to the fields of sustainable use and
management of wild resources integrating them with TEK. Finally, I discuss some of
the limitations of this study and suggest further research that could improve our
understanding of, and capacity to, include more participation of communities in
conservation processes.
Main findings
I used data from an observational study on 89 C. strictum adult trees located in
three regions with different harvesting practises in the Nilgiri Biosphere Reserve
(NBR). I used mixed effects modelling to identify significant predictors of resin
production, resin quantity, growth, reproduction, survival and seed germination. I
compared the phenology of harvested and not harvested resin trees to understand how
harvest impacts the biology. I conducted focus group discussions and informal
interviews with harvesters across my study sites to understand the TEK that exists in
relation to resin harvest and ecology of the resin trees. I used a fuzzy logic approach
to better understand the decision making processes that harvesters make in relation to
harvests from the wild.
86
Impacts of harvesting and ecology of a resin harvested species
In the forests of my study sites in the NBR, I observed that not all trees were
harvested for resin and I was interested in exploring the characteristics of harvested
trees. Overall C. strictum trees appear to produce more resin if tapping or making
incisions was practised. I found that ‘region’ which is also a proxy for harvest method
is a significant predictor of whether a tree gets harvested or not (Chapter 2). In the
Coonoor region where harvest is more opportunistic (no incisions were made on the
tree), the chance that a tree gets harvested is significantly less than in Kotagiri and
Gudalur where incisions are made to tap for resin. I also found that trees that
produced green colour flush as opposed to those that produce red colour flush
(differences in the colour of flush are reported in Chapter 3) are likely to be more
frequently harvested. I also found that quantity of resin produced by individual trees is
highly variable and found that size of the tree and number of times new incisions were
made on the tree for harvest are significant predictors of the quantity of resin
harvested (Chapter 2).
I found that harvesting of resin has no negative effect on the growth rate of the
C. strictum trees. Higher rates of growth are observed in trees located in closed and
partial light as against open light conditions. Trees that produced high number of
fruits and green colour flush also showed higher growth rates (Chapter 2). The
number of fruits produced by the C. strictum tree is dependent on the size of the tree
(large trees produced more fruit than smaller ones) and interestingly, trees which were
harvested for resin showed higher levels of fruit production and also higher seed
germination (Chapter 2). I found no significant effects of harvest on survival, however
of the six adult trees that dried up and fell to storms, during the study period, all were
harvested for resin.
87
My observational studies on the phenology of C. strictum shows that, trees
begin to produce young leaves or flush towards the end of December, going into
January sometimes continuing to March. I observed that the flowering period is
relatively short in C. strictum trees, lasting not more than 10 days, with the maximum
percentage of trees in flower in February, March and April across all sites, this occurs
before the onset of the rain period. Fruiting begins new in the months of April and no
new fruits were observed on the canopy after July (Chapter 3). I found that harvested
trees of C. strictum appear to flower more frequently than not harvested trees although
in terms of flush and fruit timings, there were no differences between harvested and
not harvested trees.
Across all study sites I observed that individual trees produced two distinct
flush colours, green and red. The probability for a tree to flush green was significantly
greater for bigger trees than small trees. Openness of canopy, fruiting intensity
(whether a tree fruited or not) and region were not significant predictors of flush
colour (Chapter 3). My observations on other animals that were dependent on the C.
strictum trees either for forage or shelter were similar to observations by local
harvesters of resin. The Langurs and Indian Giant Flying Squirrel (Petaurista
philippensis) forage on the young leaves; the Golden backed Woodpecker or
Flameback (Dinopium benghalense) has built nests in the trunk of the tree; Great Pied
Hornbill (Buceros bicornis ) feeds on the C. strictum fruits. One of the most common
sights during the fruiting season was the Malabar Giant Squirrel (Ratufa indica)
feasting on the fruits in the canopy (Chapter 3).
TEK of resin harvest
I found that resin harvesting is a prevalent practise amongst the indigenous
communities of the Nilgiri Biosphere Reserve (NBR). In some locations like
88
Nilambur in Kerala, for the Cholanayaka people resin is an important part of their
livelihood and collection is all through the year (Chapter 4). In other regions like
Chamrajnagar because of wage options and issues with access to the forests, resin
collection is still practised but not with the same intensity as in other regions of my
study (Chapter 4). Harvest methods are followed by members of the communities and
harvesters correlate these methods with the quality of the resin (Chapter 4). They also
made linkages between the ecology of the species and the presence of high number of
trees in the forest (Chapter 4). The harvesters of all the study sites discussed that
harvesting practises affect the quality of the product and some discussed attributes of
the ecology of the species that determined the population status of the trees (Chapter
4). I found that harvesters attributed the same set of factors to influencing production
of resin as I had independently assessed in my ecological studies on the species. I also
found that harvesters attributed factors such as habitat quality, size of the forest and
availability of water as key indicators of the status of resin tree populations (Chapter
4).
Further studies are warranted overall to assess the long term and short term
factors that affect resin production and conservation status of lesser studied species
like C. strictum. Resin harvest is an old practise and has been practised for more than
100 years in the experience of the harvesters of the NBR. Many of the older accounts
of the people of the region mention harvest of resin as a communal activity. One of
the further steps would be to document what they remember from the past. This
would help in creating a historical timeline of the changes and understanding what the
indigenous people perceive as the causes of those changes.
89
Contributions to scientific literature
My dissertation focuses on the ecology of a lesser studied species, C. strictum,
and examines the relationship between harvest of an exudate on the ecology and
phenology of the species. I examine the effects of the harvest on individual trees,
across regions located in different management types. I also bring in the perspective
of harvesters, who have interacted for much longer periods with the trees and the
forests that they are located in, on the ecology and management of the tree.
Trees produce resin for a number of reasons, primarily to avoid auto toxicity,
defense from parasites, herbivores and predators and resins also play a role in
attracting pollinators and seed dispersers (Langenheim, 2003). The high cost of
production of this primary metabolite is offset by the benefits of pollination, dispersal
and defense from pathogens for the tree. Harvesting resin has been shown to impact
reduction in number of fruits and viable seeds (Rjikers, 2006) and kept populations in
a vegetative state (Cunningham et al 1993, Cocks et al 2004). In contrast some studies
show that removal of resin does not affect flower or fruit production (Bitariho et al
2006; Schumann et.al 2010; Bladauf et al 2014). My study shows that harvesting of
resin from C. strictum has no negative effect on the overall growth, but that resin
harvested trees have high fruit production and germination rates of seeds than in not
harvested trees. This suggests that removal of resin has no negative impact on the
growth, reproduction and survival of the C. strictum trees. My study also shows that
harvested trees flower more than not harvested trees and also produced more fruit.
Disentangling anthropogenic factors responsible for changes in the timing of
phenological events needs to be further investigated. Nearly one third of plant species
in tropical forests delay the greening of their leaves until full expansion (Coley and
Kursar, 1996). This delayed greening strategy is thought to provide young leaves with
90
protection from herbivores; this is particularly the case with shade tolerant species
(Kursar and Coley 1992). This protection is derived from keeping the young leaves
devoid of nutrition and not by investment in expensive physicochemical defences as
previously thought (Dominy et al 2013). In the forests of the NBR especially in the
months of January to March many of the C. strictum trees are distinct because of their
bright red young leaves. My results show that not all C. strictum trees produce red
flush. This feature of the trees has not been reported elsewhere. The occurrence of leaf
colour forms within a single plant population is of both ecological and evolutionary
interest. Intra species difference in colour of young leaves has been reported by
Karageorgou and Manetas (2006) in Quercus coccifera. Smith (1986) studied the
distinct leaf colour morphs in Byttneria aculeta and concluded that the green colour
morph was more heavily attacked by herbivores and is related to the frequency of
occurrence of that morph in a particular habitat. Interestingly in the case of the
Quercus sp. photosynthetic efficiency was higher in the red coloured young leaves
and the young green leaves were more prone to herbivore attacks (Karageorgou and
Manetas, 2006). A recent study from the Himalayas showed that individuals from the
Canarium genus showed signs of folivory as early as the Miocene period (Khan, et al,
2014). This indicates that insect plant interactions have been ancient with this genus
and resulted in defence mechanisms. This is of particular interest to the study of
evolutionary ecology. My results show that probability of a tree to have green flush
was significantly higher if it was larger. I also observed green flush trees flower
gregariously and produce more resin and less fruit (Chapter 3).
My study shows that intensive harvesting leads to higher production of resin
and has no negative effects on the biology of this species. This is consistent with
earlier studies which hypothesized that collection of plant exudates like resin if
91
harvested in prescribed ways (either by traditional knowledge or science) has the least
impact on the species and its populations as compared to harvest of other vegetative
or reproductive parts (Peters, 2001). Harvesting methods and their effects on resin
production are under studied but the observations of harvesters in relation to the
ecology of the species and the changes to the environment are even more
understudied. In many communities decision-making is guided by their TEK which
deals with complexity through rules of thumb and indicators which are used to
simplify questions about natural resource use, consistent with fuzzy logic thinking
(Berkes 2009). My study is the first of its kind to use a fuzzy logic approach to
document the TEK of resin harvest.
Canarium strictum trees are found in natural habitats which are under pressure
from changing weather patterns, as observed in the drying up of seasonal streams and
springs. This necessitates investing in the long term monitoring of the biology of the
species in order to understand the linkages with the environment. In the case of C.
strictum previous studies have recorded the importance of fruits from as a food source
to rare birds and primates (Kannan, 1989; Kitamura 2011). In my study sites I report
additional findings of young leaves being foraged by primates and nesting spaces
provided by the trees. My results clearly illustrate the presence of fruit and flush
through the year, and as such make this species a good candidate for a “keystone plant
resource”. Although my study was carried out over 24 months, longer term
monitoring would shed more light on inter annual variation and on the relationships
between phonological patterns and local climate. This would contribute greatly to the
understanding and conservation of this economically and ecologically important
species.
92
Linking TEK and sustainable use and management
Indigenous communities are portrayed as custodians of conservation and
increasingly community based conservation are gaining ground, especially through
community conserved areas (Shahabuddin and Rao, 2010). Participation of forest-
dwelling indigenous communities in the conservation process is undergoing a rapid
change in the Indian context due to the recently implemented Scheduled Tribes and
Other Traditional Forest Dwellers Recognition of Forest Rights Act, 2006 also
referred to as the Forest Rights Act of 2006. More efforts based on strengthening local
knowledge based institutions and practises will empower local communities to better
manage biological diversity and put forward many suggestions on how this may be
achieved in the light of the new legislation (Bawa et al 2011). One of the important
suggestions I make is to align local knowledge and conservation science within the
citizen science work. There is a lack of space that is lacking for the participation of
some sections of society in the growing citizen science movement and this needs to be
addressed (DeVictor, 2010). My results illustrate some of the detailed knowledge that
resin harvesters in the NBR have and the indicators they use to assess resin quality
and the availability of resin trees in the forest. Community based monitoring
programs that build on these kinds of knowledge and observations can help ensure
strategies that allow for both use and conservation for the long term.
Future directions
As a two year case study on the impacts of harvest on a tree that has been
harvested for centuries perhaps, my dissertation necessarily has limitations and my
findings suggest further avenues for study.
A better understanding of several aspects of C. strictum ecology would allow
me to make more precise and improved management recommendations. Over the
93
duration of the study there was a high degree of variation in the rainfall patterns of the
three regions where the trees were located. The year 2012 was a particularly dry year
and the monsoons failed to arrive at the usual time. Given the substantial effect of
climate on phenological events (Parmesan et al, 2010) more long term studies need to
be undertaken spanning several years before management suggestions can be made.
The variation in management conditions across my study sites provided useful
comparison but confounded management and region effects. A larger number of study
sites and more replicates in terms of management practises would have been helpful
for better understanding the effects of harvest methods. I have taken several steps to
ensure that the results of my study can contribute to management decisions. This
research was designed and carried out in collaboration with Keystone Foundation,
with whom I have been affiliated for more than 10 years now. Keystone is a voluntary
agency that works on issues related to conservation, enterprise and livelihoods in the
NBR and across India. I have shared my results broadly with the NGO and presented
these results especially focussing on the need to include observations of local
communities in ecological assessments to NGO groups in the state of Orissa, North
East India and also to South East Asian network of forestry managers. I met with
harvesters of the regions in my study site to explore the possibility of a project on
community based ecological monitoring in the region. I received funding for this
project in 2013 from the Criticial Ecosystems Partnership Fund to support a group of
‘barefoot ecologists’ who are currently monitoring the quality of their forests and
recording changes to the same. It is my intention that the results of my dissertation in
addition to informing ecological theory will facilitate decision making about the
management of this important tree species. This will contribute to the community
94
based ecological monitoring program that I have initiated in the NBR. I hope it will
have long term implications for community based conservation in a biosphere reserve.
95
APPENDIX A. MAPS OF STUDY REGIONS WITH APPROXIMATE LOCATION OF SITES
Western Ghats, India Nilgiri Biosphere Reserve, Western Ghats, India
S
tat
e
bor
der
s
Coonoor
Kotagiri
Chamrajnagar
Gudalur
Nilambur
96
APPENDIX B. PHOTOS OF STUDY SITE, RESIN, RESIN TREE, AND HARVEST METHODS
B.1 Vegetation characteristics of study sites
97
B.2. Grades of resin found in the region
First grade
of resin
Second
grade of
resin
Third
grade of
resin
98
B.3. Characteristics of resin tree, Canarium strictum
Adult tree in the forest
Red flush Green flush
Buds and
flowers
Fruits
Seedlings in the forest
99
B.4. Resin harvesting tools and practises
100
APPENDIX C. DETAILS OF METHODS AND RESULTS FROM THE LINEAR MIXED EFFECTS MODELS ON PREDICTORS
OF RESIN HARVEST AND EFFECT OF RESIN HARVEST ON GROWTH, FRUIT PRODUCTION AND SEED GERMINATION
ON THE WILD DAMMAR TREE (CANARIUM STRICTUM)
Table C.1. Specifications of full linear and generalised linear mixed effects models (LMM and GLMM) used to predict resin harvest and effect
of resin harvest on growth fruit production and seed germination in C. strictum
Model Form Response variable Random
effect
Main effect Interactions
Harvest Status Binomial
GLMM
Resin harvested or
not (1/0)
Site Logdbh+Flush colour+Region+Intensity
of fruiting
Logdbh*Flush colour
Region*Logdbh
Region*Flush colour
Resin quantity Negative
Binomial
GLMM
Total quantity of resin
harvested per tree
over two years
Site Logdbh+ Region+ Fruiting intensity+
Number of incisions made+ Flush colour
Logdbh*Flush colour
Growth LMM Growth (difference
dbh year 1 and year 2)
Site Logdbh(year1)+Region+Resin quantity
harvested+Canopy status+Flush colour+
Intensity of fruiting
Logdbh*Flush colour
Region*Logdbh
Region*Flush colour
Flush colour*Fruiting intensity
Fruit Negative
Binomial
GLMM
Fruit production(total
number of fruits
produced in 2012)
Site Logdbh1+ Region +Harvest status +
Flush colour + Canopy openness
Logdbh*Flush colour
Region*Logdbh
Germination Binomial
GLMM
Seed germinated or
not (1/0)
Tree id /
Site
Logdbh+Region+Flush colour +Harvest
status
None
101
Table C.2. Estimates and standard errors for main effects and interactions that were non-significant (p>0.05) by likelihood ratio test during
model reduction in Chapter 2. All terms were significant in Growth model.
Model Main effect Estimate S.E
Harvest Status Normal fruiting intensity
Low fruiting intensity
0.8970
-0.4029
0.8035
0.7699
Resin quantity Flush colour red
Low fruiting intensity
Region Kotagiri
0.029170
0.098546
0.080061
0.076623
0.085573
0.124429
Fruit Region Gudalur
Canopy open
Canopy partial
-0.7657
0.4390
-0.2110
0.5028
0.6316
0.6726
Germination Logdbh
Flush colour red
1.4724
0.2268
0.9252
0.5200
102
APPENDIX D. UNIVERSITY OF HAWAIʻI COMMITTEE ON HUMAN SUBJECTS RESEARCH EXEMPTION
103
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