anburaj thesis - final - shodhgangashodhganga.inflibnet.ac.in/bitstream/10603/9483/6/06_chapter...

Biodiversity & Ecosystem functioning of Mid-elevation Forests of Pachamalai Hills

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CHAPTER - I

INTRODUCTION . .

The most striking feature of the earth is the existence of life, and the most

striking feature of life is its diversity (Tilman, 2000). Biodiversity is a neologism

and a portmanteau word, from biology and diversity. The science division of the

Nature Conservancy used the term “Natural Diversity” in a 1975 study, “The

Preservation of Natural Diversity.” The term biological diversity was used even

before that by conservation scientists like Robert E. Jenkins and Thomas Lovejoy.

The word biodiversity itself may have been coined by W. G. Rosen in 1985 while

planning the National Forum on Biological Diversity organized by the National

Research Council (NRC) which was to be held in 1986, and first appeared in

publication in 1988 when entomologist E. O. Wilson used it as the title of the

proceedings of that forum. The word biodiversity was deemed more effective in

terms of communication than biological diversity. Since 1986 the term and the

concept have achieved widespread use among biologists, environmentalists,

political leaders, and concerned citizens worldwide. It is generally used to equate to

a concern for the natural environment and nature conservation. This use has

coincided with the expansion of concern over extinction observed in the last

decades of the 20th century.

The biodiversity is defined as the variety and variability among living

organisms from all sources, including terrestrial, marine and other aquatic

ecosystems and the ecological complexes of which they are a part; this includes

Chapter - I Introduction


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diversity within species, between species and of ecosystems (The Biological

Diversity Act, 2002).

In another view biodiversity is simply defined as the “totality of genes,

species and ecosystems of a region”. An advantage of this definition is that it seems

to describe most circumstances and present a unified view of the traditional tree

levels at which biodiversity has been identified: i.e., Genetic diversity - diversity of

genes within a species. There is a genetic variability among the populations and the

individuals of the same species; Species diversity - diversity among species in an

ecosystem. “Biodiversity hotspots” are excellent examples of species diversity and

Ecosystem diversity - diversity at a higher level of organization, the ecosystem. It is

a broad concept, so a variety of objective measures have been created in order to

empirically measure biodiversity. Each measure of biodiversity relates to a

particular use of the data and also it related with topography, soil, climate and

geographic location of a region (Singh and Singh, 1991).

Genetic diversity denotes the variation within species in the functional units

of heredity present in any plant or animal, microbial or other origin of living things.

Species diversity encompasses the variety of species - whether wild or

domesticated, within a geographical area. Estimates of the total number of species

range from 5 million globally; though less than 1.7 million have actually been

described (FEPA, 2003).

Species diversity remains central to the evaluation of diversity at other

levels, as it is a constant point of reference in biodiversity conservation. Ecosystem

diversity refers to the variety of life forms in a given territory or area and the



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ecological processes that make them function. Ecosystem diversity is often

evaluated through measures of the diversity of the component species, the relative

abundance of different species as well as consideration of the types of species.

The global biodiversity crisis has given rise to a growing concern at the

prospect of a rapidly accelerating loss of species, population, domesticated varieties,

medicinal herbs and natural habitats. Recent estimates suggest that more than half

of the habitable surface of the planet has already been significantly altered by the

human activity and we are on the verge of mass extinction of the species.

Conservation biologists warn that 25% of all species could become extinct during

the next 20 to 30 years. The cause for the loss of species is numerous but the most

important is the loss and fragmentation of natural habitats. Biological diversity

implies the variety of living organisms and includes diversity within species,

between species and of ecosystems and the ecological processes of which they are a

part. Species diversity is considered to be one of the key parameters characterizing

ecosystems and a key component of ecosystem functioning (Scherer-Lorenzen et

al., 2005).

These are enormous tasks given the vastness of our country with its 320

million ha of landmass and 200 million ha of exclusive economic zone in the sea,

the great variety of its environmental regimes, and the diversity of its 1,25,000 is

described and an estimated 400,000 as yet undescribed species of living organisms.

Obviously, it would be essential to take resource to sampling, especially in relation

to periodic monitoring of changes in biodiversity to assess the efficacy of

conservation measures. This is also the recommendation of the major review of the



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subject, the Global Biodiversity Assessment (GBA) commissioned to provide the

background for launching a global effort at inventorying, monitoring conservation

and sustainable utilization of biodiversity (Heywood, 1995). GBA suggests that

monitoring would have to be based on broad scale sampling employing remote

sensing and measures at the level of the biotope and the landscape, in conjunction

with point - sampling at a representative selection of localized sampling points.

Data from a series of points, coupled to remote sensing should then provide

information that can be extrapolated from global coverage.

The Convention on Biodiversity (CBD) is a landmark in the environment and

development field, as it takes for the first time comprehensive rather than a sectoral

approach to the conservation of earth’s biodiversity and sustainable use of

biological resources. The CBD was negotiated and signed by nations at the UNCED

Earth Summit at Rio de Janeiro in Brazil in June 1992. The Convention has come

into force on December 29, 1993. India became a Party to the Convention in 1994.

At present, there are 175 Parties in this Convention (The Biological Diversity Act,

2002). The main objectives of the convention were Conservation of biological

diversity; Sustainable use of the components of biodiversity; Fair and equitable

sharing of benefits arising out of the utilization of genetic resources.

The biodiversity supports the ecosystem function essential to life and provide

numerous services and products to mankind. It has been placed globally in the

context of sustainable development, poverty eradication and the Millennium

Development Goals and Targets. Biodiversity has been raised up the political



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agenda by the Secretary General, WEHAB initiative and through attention within

the plan of implementation.

The main issues and challenges facing biodiversity include: more than one

billion people live in extreme poverty and their livelihood are severely affected by

biodiversity loss, water pollution and land degradation; economics of biodiversity

are not well understood; many species become extinct, threatened, endangered or

depleted; genetic diversity of crop plants are being lost; wetlands and coral reefs are

being lost or degraded. Other obstacles include political, institutional, technical,

capacity, lack of knowledge, socio-economic policy, legal, natural phenomena and

environmental obstacles.

The world summit on Sustainable Development recognized these issues,

challenges and obstacles and suggested remedies provided in the Plan of

Implementation. These include free trade, targets and timeframe biodiversity

mainstream, monitoring and review, indicators, resources, partnership institutions,

political will and linkages between biodiversity and culture. Framework for actions

focuses on integrating biodiversity into development programmes and economic

sector’s plan and strategies; halting the biodiversity loss and restoring it in degraded

areas.

Identifying the processes that determine species diversity remains a

challenge in ecological research (Loreau et al., 2001). Numerous studies on small

spatial scales show that habitat quality plays an important role for plant species

richness, with soil properties and light being the most commonly studied

environmental factors. Besides habitat quality, landscape structure and history are



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considered as important factors for species richness and species occurrence

probabilities.

Landscapes are constantly changing and, for plant species, this means that

some suitable patches disappear while others emerge. Distribution of suitable

habitat patches but also on a species ability to persist in habitats that are already

unsuitable and disperse to habitats that have become suitable. Distribution of

species in such landscapes thus strongly depends on the spatio - temporal structure

of the landscape and on species traits.

The assessment of biodiversity in managed landscapes remains a problem for

mainly two reasons; (i) Diversity measures strongly depend on the chosen spatio-

temporal scale of the prevailing assessment, and unfortunately there are no

satisfying scaling functions applicable to transfer results to another scale. (ii)

Relations between biodiversity and land - use are generally very complex (Szaro

and Johnston, 1996). Besides ‘Natural’ and ‘Anthropogenic’ environmental

conditions, ecological processes and socio-economic factors have to be taken into

account.

An ecosystem classification that aims to reflect potentialities, attention is

divided among layered structure, floristics, dominance, edaphic factors,

microclimate, and succession. All parts of the landscape that support, or are capable

of supporting, what seems desirable to consider as the same kind of relatively stable

phytocoenosis in the absence of disturbance, comprise one habitat type. Each of

these has different kinds of potential vegetation, depending on whether it is free of

disturbance or is regularly burned or grazed, etc. Ordinarily one habitat type is



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highly discontinuous, with intervening areas occupied by other habitat types

differentiated by either soil or microclimate. The communities occupying the

scattered units of one habitat type usually embrace a wide variety of serial stages as

a result of disturbances at varied time in the past. In different places climax

vegetation in this habitat type may play the role of climatic, edaphic, or topographic

climax, but it may be restricted to only one or two of these roles. Although each

habitat type is conveniently identified using vegetation, and appropriately named

after a distinctive combination of plants in climax, other biotic and some physical

characters of the habitats are often useful in their definition.

Since each piece of demonstrably seral vegetation, as well as each disclimax,

can be related dynamically to someone primary climax, a system based on habitat

types in infinitely simpler than one giving equal weight to all describable types of

plant cover. This emphasis on potentialities regardless of the current status of the

vegetation permits the closest possible correlation among vegetation, microclimate,

and soil.

Ecosystems that have lost their resilience tend to ‘flip’ into another

ecological state. Ecosystems that are on the verge of a flip are ‘fragile’. Fragility of

any ecosystem does not become apparent readily. It starts in the form of local

‘decay’. The first sign of decay in an ecosystem is the loss of species. Loss of

species leads to the breakdown of ecological integrity. Globally, signs of decay in

biodiversity rich ecosystems led to the designation of certain landscapes as

‘biodiversity hotspots’. And since Norman Myers and colleagues first proposed the

concept in the late 1980s (Myers et al., 2000), there have been attempts to designate



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areas around the globe not only as hotspots, but also as ‘hot - specks’ and ‘warm -

spots’.

Fragile ecosystems include deserts, semi - arid lands, mountains, wetlands,

small islands and certain coastal areas. Most of these ecosystems are regional in

scope, as they transcend national boundaries. Sensitive and fragile ecological

environment is caused by an unbalanced distribution of ecological system

substances and energy in a specific geographical setting. In a fragile ecosystem even

a small additional change or disturbance can create huge losses because within such

ecosystems the loss of one species alone can create a probability of survival

collapse for many other through the symbiotic chain. Thus, considering the

vulnerability of the fragile ecosystems, there is a need to promote awareness about

the concept itself and to ensure that the ecological resources are conserved for better

management and sustainable utilization of any fragile zone.

The relationship between biodiversity and ecosystem functioning has

emerged as one of the most exciting integrated research in ecology in the last

decade. Faced with the prospect of a massive, irreversible loss of biodiversity,

ecologists have begun investigating the portential consequences of these dramatic

changes in biodiversity for the functioning of natural and managed ecosystems.

These investigations have been motivated by both the scientific challenge and the

need to understand better the role biodiversity plays in providing sustainable

ecological goods and services for human societies.

The recent advances made in functional biodiversity research led to a new

synthetic ecological framework, which has even been denoted as a new paradigm of



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ecology. While biodiversity has historically been seen as a response variable that is

affected by climate, nutrient availability and disturbance, this new emerging

paradigm, called ‘Biodiversity - Ecosystem function Paradigm’ (Naeem, 2002), sees

the environment primarily as a function of diversity, underlining the active role of

the biota in governing environmental conditions. More specifically, within this

framework, a specific ecosystem function is thus seen as a function of (i)

biodiversity and the functional traits of the organisms involved, (ii) associated

biogeochemical processes, and (iii) the abiotic environment. This is not only of pure

academic interest, but it has important implications for the conservation and

sustainable management of biological diversity.

Ecosystem functioning reflects the collective life activities of plants, animals,

and microbes and the effects these activities feeding, growing, moving, excreting

waste, etc. have on the physical and chemical conditions of their environment.

A functioning ecosystem is one that exhibits biological and chemical activities

characteristic for its type. A functioning forest ecosystem, for example, exhibits

rates of plant production, carbon storage, and nutrient cycling that are characteristic

of most forests. If the forest is converted to an agro-ecosystem, its functioning

changes.

Forest plays an important role in the water cycle, carbon sequestering, as a

genetic bank and source of food; they stimulate rainfall, protect soils from erosion

and regulate the flow of water. Tropical forests are disappearing fast while the

number of people depending on them grows steadily. It is worthy of note that as

environmental services are degraded and users become affected, people become



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more environmentally conscious and will want to protect the environment. It is

stated that knowledge and skills have always played an important role in economic

growth. With education, labour productivity is greatly enhanced, resulting in

increased physical capital and it is universally acknowledged that technology is

produced at a cost by investment in research and development. In order to do this

effectively, there is a need for a substantial investment in education and research by

governmental, policy makers, non governmental bodies as well as the private sector

participation including extension for forest conservation and protection.

Ecosystem processes are quantified by measuring rates of these movements

(e.g., plant production, decomposition, nutrient leaching or other measures of

material production, transport or loss). Ecosystem functioning, in turn, is quantified

by measuring the magnitudes and dynamics of ecosystem processes.

Ecosystem functioning results from interactions among and within different

levels of the biota, which ecologists describes as a nested hierarchy. For instance,

green plant production on land is the end product of interactions of individual plants

nested within populations; interactions among populations nested within a single

species; interactions among a variety of species nested within a group of

functionally similar species; and so on upto the level of interactions between

different types of ecosystems nested within landscapes. Although every organism

contributes to ecosystem processes, the nature and magnitude of individual

contributions vary considerably. Research in biodiversity places much emphasis on

the uniqueness of individual species and their singular contributions to ecosystem

services.



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The influence of changing biodiversity on ecosystem functioning has been a

central and rapidly growing theme in ecology during the last decade. Research in

this area is motivated in significant part by the practical issue, cited within the first

paragraph of most publications on the subject, of understanding how declining

diversity influences ecosystem services on which human depend. The most

influential empirical research on biodiversity - ecosystem functioning (BD-EF)

linkages has been the series of experiments manipulating diversity in grasslands

(Tilman et al., 2002) and in aquatic microbial microcosm. Typically these have

tested how ecosystem - wide biomass accumulation or metabolic rates change along

gradients of species richness achieved by randomly assembling experimental

communities from a pool of species. The grassland experiments have manipulated

plant species richness, and sometimes also functional group richness. The microbial

experiments more often have manipulated several tropic levels simultaneously, but

usually with proportional changes at each level. Several such experiments have

demonstrated significant positive correlations between species richness and plant

biomass accumulation or metabolic rates. The functioning of ecosystems has long

been known to depend on the identities of the species and ecosystems contained. It

also depends on the number of species. At each level of diversity, there must be

numerous replicate ecosystems, each with a random and independent combination

of species chosen from the species pool.

The realization that biodiversity play a key role in ecosystem functioning has

been an important step forward in ecology, and a powerful tool in facing the

challenge of accelerated loss of biodiversity at the global scale. Many initiatives



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have been launched aiming to document the possible effects of species or functional

types on major ecosystem processes. Most of them are based on experiments on

synthetic communities. In which different combinations of species or functional

types are planted in order to represent different biodiversity treatments.

The type and nature of vegetation cover has an important influence on soil

formation and structure, and in a number of cases may appear to be the most

important soil influencing factor, largely due to the interaction of plant roots which

extract water and nutrients, with the fall of leaves, and other organic debris

enriching the soil in various ways. Different plant communities have varying effects

on the soil. Deciduous trees have deep root systems drawing nutrients from depth

and so tend to counteract leaching. Their leaves decompose readily to recycle

nutrients and add humus to the soil. A wide range of organisms live in the soil

beneath deciduous trees. Grassland recycles nutrients rather like deciduous

woodland, but with shallower root systems, leaching may become more prevalent

and the soils gradually lose nutrients and become more acidic.

The influence of organisms on soil formation depends upon the niche they

occupy and upon their life strategies. Decomposers, such as bacteria, live in the

surface organic horizon and ingest organic material. Burrowers live below the

surface in the mineral horizon and ingest both mineral and organic material. Grazers

eat vegetation on the soil surface. Predators can live in or on the soil surface and

prey on the other biota. With the exception of predators, these organisms affect soil

directly through the transformation of organic matter, predators act indirectly by

returning organic material to the soil through excretion (Cottle, 2004).



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It is apparent that the characteristics of any particular soil type represent the

influences and interactions of a number of key physical and biological components

and processes. The nature of the parent material (i.e. the bedrock or derived

geological material) is but one of these components. The influence of parent

material on soil formation will vary depending on the nature of interaction and

strength of influence of the other factors. In this way, it may be that in certain

instances (e.g. scree slopes, arid environments) bedrock comes to play a more

significant role on overall soil formation and as a consequence the type of

vegetation that a soil may support.

Litter production and subsequent decomposition are key process in carbon

and nutrient cycling of forest ecosystem. The physical and chemical breakdown of

organic matter during decomposition releases both CO2 and nutrients, the latter

being again available for plant nutrition. The decomposition rate of leaf litter is

influenced by its physico-chemical properties such as lignin/nitrogen ratio, C:N

ratios, physical and leaf toughness, physical barriers on leaf surface, but also by the

composition of soil organisms and microclimatic conditions. Therefore, litter

decomposition and the turnover of labile soil organic matter could be affected by

plant species diversity due to differences among species in litter quantity and

quality, in timing of litter inputs, but also due to different microclimatic conditions

within a stand. These differences may also result in changes of the abundance and

composition of the soil fauna and microbial community. Decomposition rates of

litter mixtures are higher than expected based on decay rates of single - species

litter. The relationship between litter species richness and decomposition rates or



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nitrogen dynamics is thus difficult to predict with the identity of the species within a

mixture and their functional traits possibly being more important than the number of

species.

Plant-microbe interactions are an influential part of ecosystem functioning,

and have recently gained attention in the context of invasion biology (Van der

Putten et al., 2007). Previous research credits invasive weeds with decreasing the

aboveground biodiversity of the invaded range by displacing or even eradicating

native plants and disrupting the migration patterns of animals that are associated

with those native plants (Hierro and Callaway, 2003). However, there is only

limited information concerning the impact of invasive plants on the belowground

biodiversity in soil microbial communities. Invasive plant species are thought to

benefit from a lack of coevolved pathogens in their nonnative range (Keane and

Crawley, 2002), yet few studies comprehensively examine soil microbial

community dynamics and their response to novel plant influences. As below and

above ground communities are linked through feedback interactions, assessing the

impacts of invasive plants on soil microflora may provide new insight into the

mechanism by which some invaders are able to dominate landscapes and displace

native plants (Wolfe and Klironomos, 2005).

Plant-butterfly interaction is a co-evolutionary process and a typical example

to understand the mutual interactions. This interactions created a selection processes

on vegetation for the richness and dispersal. The nectar feeder and during their

evolution over time and space developed intricate association with plants either in

the adult or larval stages. It resulted in some butterflies, which pollinate during



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feeding to attract the butterflies by the shape, colour and various patterns of

pigmentation on corolla, scent and quality of the nectar. The butterflies sometimes

get attracted to saps, juices which ooze out, sugary solutions and even to toddy pots.

There are few butterflies which get attracted to bird droppings and excreta. Some

possibly sip even moisture and water.

Angiosperms are the most abundant and diverse group of terrestrial plants. In

addition, relationships with pollinators are ubiquitous with nearly 80 percent of all

flowering plants using animals to undertake sexual reproduction. Certain species of

pollinators may choose specific plant species based on floral phenotypes. Variation

in floral phenotypes is also common within species and populations. This has

prompted evolutionary biologists to explain this floral diversity as mediated by

pollinator choice. However plant - pollinators interactions are largely general with

most plants receiving visits from multiple pollinators and pollinators visiting

multiple plants species. Therefore it is unlikely that many floral traits are mediated

by tight coevolution with a particular species. Plant must not interact with

mutualists but also with natural enemies. Additionally, floral phenotypes that attract

pollinators may also attract natural enemies. These herbivores and other enemies

may than mediate the selection on floral phenotypes.

Understanding the fascinating changes that have shaped the evolution of

parasitic plants would be greatly facilitated, from both morphological and molecular

standpoints, by detailed comparative studies with their closest non - parasitic

relatives. However, the phylogenetic position of parasitic angiosperms and their

precise relationship to autotrophic relatives are not easy to deduce (Nickrent et al.,



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1998). In general, problems are encountered with both morphological and molecular

evidence. Parasitism is associated with extreme reduction and/or modification of

vegetative structures, and convergence with other parasitic taxa is common. Both

phenomena are encountered in Cuscuta. The morphology of this parasitic genus is

characterized by loss of roots, significant reduction of chlorophyll synthesis, almost

complete reduction of leaves and cotyledons, and the evolution of haustoria, organs

that enable these plants to connect to the host. Both Cuscuta and Cassytha are

pale, twining, stem parasites, and provide an excellent example for convergent

evolution in parasitic plants (Kuijt, 1969).

Balanophoraceae, members are highly reduced parasites that attached to the

roots of their host, spend most of their lifetime underground. The vegetative body

varies from genus to genus but basically consists of an irregular roundish mass,

called a tuber, and a set of slender outgrowths referred to as roots, rhizomes of

runner. Due to evolutionary reduction, the bodies may lack leaves, auxiliary buds,

stomata, a true epidermis, and even the ordinary custele organization of vascular

tissues (Mauseth et al., 1992).

The planet's biodiversity is increasingly threatened by human activities. The

global steps to stop the damage have forged numerous international panels and

agreements over the past 15 years. Yet despite these efforts to ensure biodiversity

conservation, it is witnessed extensive population extinctions and massive

deforestation and fragmentation of natural habitats, and we may even see the

geographic contraction of major ecosystems. The quantification of species

extinction is poor, yet we do know that the number of threatened species, including



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the most charismatic animals, is considerable. For example, 25% of all the

mammals on the planet are endangered. Obviously, there continues to be problems

with enforcing conservation in the face of social and economic growth in

industrialized and developing countries.

The anthropogenic disturbances play an important role in change, loss or

maintenance of plant diversity of a region. Trees are lopped for fuel wood, fodder

for the domestic animals, timber for house construction and industrial raw materials.

Various produces like removal of forest floor biomass, edible fruits, fibre, gum,

resin, dyes, tannin, spices and more importantly, medicines are exploited from the

forests. These anthropogenic disturbances not only influence the soil, nutrient and

water conditions, but also influence climatic conditions. The conservation and

management of biodiversity of the forests will be important for the sustainability

and improvement of soil nutrient and water conditions of a region (Jeet Ram et al.,

2004).

Agro-biodiversity performs a variety of ecological services beyond the

production of food, including recycling of nutrients, regulation of microclimate and

local hydrological processes. In natural ecosystems, the vegetative cover of a forest

or grassland prevents soil erosion, replenishes ground water and controls flooding

by enhancing infiltration and reducing water runoff. In agricultural systems,

biodiversity performs ecosystem serves beyond production of food, fiber, fuel, and

income. Examples include recycling of nutrients, control of local microclimate,

regulation of the abundance of undesirable organisms, and detoxification of noxious



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chemicals. These renewal processes and ecosystem services are largely biological,

therefore their persistence depends upon maintenance of biological diversity.

When these natural services are lost due to biological simplification, the

economic and environmental costs can be quite significant. Economically, in

agriculture the burdens include the need to supply crops with costly external inputs,

because agro-ecosystems are deprived of basic regulating functional components,

lack the capacity to sponsor their own soil fertility and pest regulations. Often the

costs involve a reduction in the quality of life due to decreased soil, water, and food

quality when pesticide and nitrate contamination occurs. The net result of

biodiversity simplification for agricultural purposes is an artificial ecosystem that

requires constant human intervention, whereas in natural ecosystems the internal

regulation of function is a product of plant biodiversity through flows of energy and

nutrients, and this form of control is progressively lost under agricultural

intensification.

Agricultural production can strongly influence biodiversity and ecosystem

processes, often changing community composition, plant biomass, vegetation

structure, and nutrient cycling because of interactions between biological, social,

and economic factors. Researchers and conservation organizations have recently

paid considerable attention to diverse agroecosystems. These traditional plantations

are enriched by nontimber forest products and maintain many of the ecological

characteristics of natural forests. Such multi resource land-use practices that create

new landscape elements can help to conserve biodiversity to regulate pests and

disease and can be efficiently adapted to changing socioeconomic conditions,



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ecological conditions, household needs, and marketing opportunities. They also

may provide opportunities for developing new approaches in the conservation of

tropical rainforests and biodiversity and may increase the public’s awareness that

indigenous land - use systems can be useful for sustainable development.

Biological diversity is an asset of vital significance to human beings, as it

provides food, medicine and industrial raw materials along with an immense

potential for acquiring many unknown benefits to future generations. The areas rich

in biodiversity are also an abode of diverse ethnic groups possessing a valuable

reservoir of indigenous knowledge system (IKS) acquired and developed during a

long period of time. A rapid pace of development in the regions populated by tribal

communities and amalgamation of tribal societies with mainstream societies has led

to a threat of gradual erosion of indigenous knowledge base, accompanied with an

imminent danger of bio-piracy of valuable resources and knowledge systems (Das

and Shukla, 2007). Therefore, an integration of traditional knowledge with modern

scientific developments by value addition is an essential requisite for successful

application of IKS for economic welfare of the tribal societies. The plants around

the habitats of the tribal population not only provide food for living organisms, but

also produce different chemicals necessary for human health. It is not possible to

provide modern health care to all the people at affordable cost. In this juncture,

folklore plays a vital role in the primary health care of tribal people. They depend

on natural flora to meet their healthy life (Das and Shukla, 2007).

Forests are the most valuable natural resources available to the mankind on

planet earth. On the one hand, they are the essential source of livelihood for the



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poor and marginalized section of the society; on the other hand they provide

furniture and other items of desire for the rich. To reverse the degradation in

resources, action programmes for conservation and development of forest resource

have taken shape in most of the countries. Rapid deforestation has added to the

excess heat on earth. World community especially the political leadership and

intellectual class in the developing countries should act and take mitigating steps to

control the global warming. The protective and productive role of forests in this

regard assumes importance.

Ethnobotanical studies are often significant in two dimensions i.e.

environmental protection and human utilization point of view. Right from its

beginning, the documentation of traditional knowledge, especially on the medicinal

uses of plants, has provided many important drugs of modern day (Flaster, 1996).

Since the beginning of the discipline, ethnobotanists have been concerned with the

threat to traditional cultures and their knowledge of plant uses and relationships.

Over the last three decades of the past century, work was centered on the need to

catalogue knowledge of plants in a race with the fast disappearing of natural

resources, primarily Tropical Forests. It is clear that there is a close correlation

between the destruction of tropical forests and other ecosystems and the decrease of

biological diversity as well as cultural loss. Many ethnobotanists ventured to

faraway places to catalogue all the plants indigenous people used in their everyday

lives before their ecosystems were converted to cattle ranges, oil fields or

monoculture plantations (Carlos, 2007).



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According to WHO (2001), 80% of the world population uses natural

remedies and traditional medicines. In recent times, despite all the advances made

in modern medicine, traditional medicine has gained renewed interest in health care

services. This may be attributed to increased awareness in the potential and curative

ability of the alternative medicines and particularly as a result of the various

shortcomings revealed for several synthetic drugs. In tropical Africa, inadequate

access to western medicine and physicians coupled with high procurement cost for

drugs have led to about 70% of the population to rely greatly on different plants to

meet their traditional health care services.

Most of the people depending on traditional medicines live in developing

countries and they rely mainly on the traditional herbal medicine to meet their

primary healthcare needs. India is very rich in ethnobotany heritage due to its rich

cultural diversity. Over 16,000 species of higher plants are occurring in India, of

which approximately 9,000 are known to be economically useful. Of these, 7,500

are used for healthcare by various ethnic communities in India.

The importance of the environment and forest ecosystem to human survival

can never be over stressed. Humans depend on the relationship with the

environment for safety, health and survival. The present situation, where the

environment is recklessly assaulted and degraded by individuals and corporate

bodies, portrays serious danger to all life forms and it unveils man’s ignorance in

terms of environmental education and consciousness.

About 2,48,000 species of plants and 1.4 million animal species have been

described worldwide. Tropical forests are rich in biodiversity and their loss is



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currently approaching 20 m.ha per annum which will undoubtedly lead to

perishmint of global species and genetic diversity. Successful conservation of

tropical of forests will depend on balancing many conflicting interests and it will be

important to have both quantitative information about biodiversity and methods for

monitoring change.

India is recognized as a country rich in all aspects of Biodiversity viz.,

ecosystem, species and genetic diversity mainly due to the tropical location,

disparate physical features and climatic types (Jain, 1987). India is one of the 12

mega biodiversity countries of the world and one among the 194 signatories to the

Convention on Biological Diversity (CBD) at Earth Summit in Rio de Janeiro in

1992. By virtue of a wide variety of physical and climatic conditions, India harbours

varied ecosystems ranging from the tropical rain forsts to high alpine cold deserts,

grasslands, wetlands and coasts. India harbours varied ecosystems ranging from the

tropical rain forests to high alpine cold deserts, grasslands, wetlands and coasts.

India embraces three major biological realms, viz. Indo-Malayan, Eurasian and

Afro-tropical and is adorned with 10 biogeographic zones and 26 biotic provinces

(Rodgers and Panwar, 1990). With only 2.5 % of the earth’s land area, India

accounts for 8 % of the recorded species of the world which includes millions of

races, subspecies and local variants of species and the ecological processes and

cycles that link organisms into population, communities, and all different

ecosystems (Venkataraman, 2006). Demographically, it is the second largest

populated country in the world and a majority of its population directly depends on

biological resources of livelihood.



23

It is estimated that India has approximately 45,000 species of plants

representing as much as 11 % of the world’s flora (Mudgal and Hajra, 1997). This

includes about 17500 species of flowering plants, 48 species of gymnospers, 1200

species of pteridophytes, 1980 species of mosses, 845 species of liverworts, 6500

species of algae, 2050 species of lichens 14,500 species of fungi and 850 species

bacteria. India holds a prominent position among the eight Vavilovian Centers of

origin of cultivated plants, which is the geographic region where crops exhibit

maximum diversity in terms of number of races and botanical varieties (Vavilov,

1926). Today, about 166 crop species and well over 324 species of wild relatives of

crop plants are recognized and utilized for food production. Wild edible plants

account for nearly 1000 species serving various purposes; 145 as roots/tubers, 526

as leafy vegetables/greens, 101 for buds/flower, 647 for fruits and 18 for seeds and

nuts (Anonymous, 1994).

Though, India can boast of having an impressive range of biological

diversities, there is hardly any scope for complacency. Ever mounting human

population, rapid expansion of agriculture, industry, urbanization and large scale

developmental projects such as dams, highways, mining have led to habitat

destruction, fragmentation, degradation and over exploitation of biological

resources. Coupled with these factors unsustainable resource use practices and

illegal trade of high value wildlife products have severely threatened many species

of flora and fauna. The agro-biodiversity has also suffered seriously due to

introduction and promotion of few ‘high yielding’ varieties. Yet very little has been

done to harness the traditional knowledge on biodiversity inherited by a large



24

number of local communities, given that India has had rich tradition of conserving

nature and natural resources. Worship of trees, forests, rivers, Ponds Mountains and

association of animals and birds with gods and goddesses had contributed

immensely to their conservation during historic past.

Tamil Nadu is endowed with a rich biodiversity. The main natural habitat

types are Forest, Mountains, Rivers, Wetlands, Mangroves and Beaches. Tamil

Nadu has a geographical area of 1,30,058 km2, which constitutes about 4 per cent of

the country's total area. Tamil Nadu shares the Western Ghats (one of the 25

biodiversity hotspots) with the states of Kerala, Karnataka, Goa, Maharashtra and

Gujarat. It shares the Eastern Ghats with the States of Andhra Pradesh and Orissa.

Tamil Nadu accounts for nearly ⅓rd of the total flora of India. Species and Generic

diversity of flora of Tamil Nadu is comparatively richer than the neighbourhood

states. The state of Tamil Nadu harbours a total of 5547 taxa that includes 5239

species, 72 subspecies and 548 varieties distributed in 231 families under 1668

genera. Dicots constitute a major part of the flora that account for 78 per cent

comprising 1944 taxa of Polypetalae, 1720 taxa of Gamopetalae and 642 taxa of

Monochlamydeae. Number of Monocots in Tamil Nadu includes 1241 taxa

(Narashimhan, 2005). It is reported that 123 plant species are considered

endangered by Botanical Survey of India. The conservation of a wide variety of

species in natural forests depends on maintaining essential functional components

of the relevant ecosystem. The regional level conservation need to protect the

valuable species. In the light of the above, the present study on biodiversity and

ecosystem functioning was framed with the following objectives.



25

1. To identify the major ecosystems, vegetation type, and landscape elements in

the study area.

2. To study the total number of plant species by random sampling collections in

the study area.

3. To find out the species richness diversity analysis by Shannon Weiner’s index.

4. To analyze the ecosystem functioning by ecological interactions and nutrient

recycling.

5. To understand the anthropogenic interaction on vegetation.

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