Term paper Report On

CARBON SEQUESTRATION UNDER VARIOUS LAND-

USE SYSTEMS

Prepared by Ajoy Debbarma

Submitted in partial fulfilment of the

requirement for award of the degree

M.SC. (ENVIRONMENT MANAGEMENT)

2010-12

FOREST RESEARCH INSTITUTE UNIVERSITY Indian Council of Forestry Research and Education

Dehradun

FOREST RESEARCH INSTITUTE UNIVERSITY

(INDIAN COUNCIL OF FORESTRY RESEARCH & EDUCATION)

P.O.: I.P.E. KAULAGARH ROAD, DEHRADUN-248195

CERTIFICATE

This is to certify that the term paper work entitled “Carbon

Sequestration Under Various Land-Use Systems” is a bonafide

work carried out by Mr.Ajoy Debbarma, a student of M.Sc.

Environmental Management (2010-12) of Forest Research Institute

University, Indian Council of Forestry Research and Education

(ICFRE), Dehradun, submitted in partial fulfillment of the requirement

for the award of M.Sc. (Environmental Management) degree.

The work has been carried out under the supervision of

Dr. C.M. Mathavan,Scientist-C, Forest Soil and Land Reclamation

Division, FRI, Dehradun.

Dr. Ramesh Kumar Aima, IFS Place: Dehradun Dean (Academics)

Dr. Ramesh K. Aima, IFS Dean (Academics)

Phone : 0135-2752682 Fax : 0135-2752682 EPAB : 0135222 : 2757021 – 26 Extn. : 4452 (O) E-mail : aimark@icfre.org

FOREST RESEARCH INSTITUTE UNIVERSITY

Indian Council of Forestry Research & Education

(An autonomous body of Ministry of Environmental & Forests, Govt. of India)

P.O. NEW FOREST, DEHRADUN- UTTARAKHAND -248006

CERTIFICATE

This is to certify that the term paper report entitled “Carbon

Sequestration Under Various Land-Use Systems” submitted

in partial fulfillment for award of the degree “M.Sc. Environmental

Management” (2010-12) of Forest Research Institute University,

Dehradun is a bonafide work carried out by Mr. Ajoy Debbarma

under my guidance.

Dr. C.M. Mathavan Place: Dehradun Scientist-C, Forest Soil and Land Reclamation Division

Dr. C.M. Mathavan,

Scientist-C,

Forest Soil and Land

Reclamation Division,

Forest Research Institute,

Dehradun,India.

Phone : 91-9458343959

Extn : 4471

E-mail : cmmathavan@gmail.com

DECLARATION

I hereby declare that the term paper report entitled “Carbon Sequestration

Under Various Land-Use Systems” submitted in partial fulfilment of the degree of M.Sc

Environmental Management of FOREST RESEARCH INSTITUTE UNIVERSITY,

Dehradun is a bonafide work carried out by me under the supervision of Dr. C.M.

Mathavan, Scientis–C, Forest Soil and Land Reclamation Division, Forest Research

Institute, Dehradun and that no part of this work has been submitted for any other degree

or diploma.

Any part of the text if used without prior written permission of the guide would be

considered as intellectual property rights violation.

Place: Dehradun Ajoy Debbarma M.Sc. (EM) FRI University

ACKNOWLEDGEMENT

I acknowledge with profound gratitude my indebtedness to my supervisor Dr.C.M.

Mathavan, Scientist-C, Forest Soil and Land Reclamation Division, Forest Research

Institute, Dehradun (Uttarakhand) for suggesting solutions to my problems and

guiding me during the entire course of academic work relating to the subject.

I am extremely grateful to Director of Forest Research Institute University, Dehradun

(Uttarakhand) for providing me facilities and general encouragement.

I am grateful to the Dean, F.R.I Deemed University, Dehradun for providing me an

opportunity to work upon this topic.

I thank the Course Co-ordinator, Dr.(Mrs.) S.S. Negi ,Ecology and Enviroment

Division for her timely guidance.

I am also greatly indebted to my friends who have helped me immensely during

compilation of this term paper work.

Above all, I would like to thank my parents and well-wishers for everything I achieved till

date.

Place: Dehradun Ajoy Debbarma M.Sc. (EM) FRI University

INDEX

1. INTRODUCTION

2. OBJECTIVES

3. REVIEW OF LITERATURE

4. METHODOLOGY

5. GLOBAL CARBON SINK CONCEPT

6. INDIAN SCENARIO OF TERRESTRIAL CARBON SEQUESTRATION UNDER VARIOUS LAND USE SYSTEMS

7. LAND USE CHANGES & SOIL CARBON SEQUESTRATION

8. CARBON SEQUESTRATION POTENTIAL OF VARIOUS TERRESTRIAL

ECOSYSTEMS

9. CONSEQUENCES

10. CONCLUSION

1. INTRODUCTION

Human activities related to land conversion and agricultural practices have

contributed to the build up of carbon dioxide to the atmosphere. During the past

150 years, land use and land-use changes were responsible for one-third of all

human emissions of CO2 (IPCC 2001). Over the next 100 years, global land-use

change and deforestation are likely to account for at least 10 percent of overall

human caused CO2 emissions. The dominant drivers of current and past land-

use-related emissions of CO2 are the conversion of forest and grassland to crop

and pastureland and the depletion of soil carbon through agricultural and other

land-management practices. Past CO2 emissions from land-use activities are

potentially reversible, and improved land-management practices can actually

restore depleted carbon stocks. Therefore, there are potentially large

opportunities to increase terrestrial carbon sequestration.

Of the five principal global carbon pools the ocean pool is the largest at 38.4

trillion metric tons (mt) in the surface layer, followed by the fossil fuels (4.13

trillion mt.), soils (2.5 trillion mt. to a depth of 1m), atmosphere pools (800

billion mt) and biotic community (620 billion mt) [Lal, 2009]. In terrestrial

ecosystems, the amount of carbon in soil is usually greater than the amount of in

living vegetation. When soil are tilled organic matter previous protected from

microbial action is decomposed rapidly and release CO2 in to atmosphere

because of changes in water, air and temperature conditions, and break down of

soil aggregates. Carbon concentration in the atmosphere is increasing at the rate

of about 4 billion mt (2ppm) per year. This increase is a double jeopardy viz., loss

of carbon from terrestrial pools reduces the ecosystem services and goods that

these systems provide; in particular decline in soil quality adversely affects use

efficiency of inputs decreases agronomic yields and exacerbates food insecurity

and increase in atmosphere pools accentuates global warming with the

attendant impact on pole-ward shifts of ecosystems and increase infrequency

and intensity of extreme events like drought, sea level rise and biodiversity loss.

One solution to this problem is to transfer atmospheric CO2 in to other long–

lived pools such as soil and biotic pools. This is called carbon sequestration.

Carbon sequestration is the process by which atmospheric carbon dioxide is

taken up by trees, grasses and other plants through photosynthesis and stored as

carbon in biomass (trunks, branches, foliage and roots) and soils. C-

sequestration is a natural, cost-effective and environmental friendly process. It is

win-win option. Forest vegetation and

Soils constitute a major terrestrial carbon pool with the potential to adsorb and

store carbon dioxide (CO2) from the atmosphere. Because of the large areas

involved at regional / global scale, forest ecosystem play a vital role in carbon

storage; capture and release large amounts of carbon and have the capacity to

influence atmospheric carbon dioxide concentration and climate dynamics.

Evidence of climate change linked to human induced increase in green house gas

(GHG) concentration is well-documented in international studies (IPCC 2001,

2007). The term "sinks" is also used to refer to forests, croplands, and grazing

lands, and their ability to sequester carbon. The main objective of carbon

sequestration is to reduce the atmospheric carbon dioxide concentration to

reduce the impact of global warming.

While mitigating climate change by off-setting fossil fuel emissions, it also

improves quality of soil and water resources, enhance agronomic productivity

and buy us time to identify and implement viable alternatives to fossil fuels. An

increasing carbon pool in the soil beyond a threshold level (about 1.2% in the

surface layer) is essential to enhancing soil quality increasing crop productivity

and improvement of water quality. Soil organic carbon (SOC) has been depleted

through long term use of extractive farming practices and conversion of natural

ecosystems in to crop lands. Most of agricultural soil lost 30 to 40 mt of carbon

per ha and their current reserves of soil organic carbon are much lower than

their potential capacity.

Soil carbon (C) sequestration involves adding the maximum amount of carbon

possible to the soil. C- Sequestration potential is higher in degraded/ desertified

soils and cultivated soils. Thus converting degraded / desertified soils in to

restorative land and adopting Recommended Management Practices (RMPs) can

increase the soil carbon pool (Lal, 2009). RMPs include no-till, use of soil

amendments and organic manures, crop rotations and recommended stocking

rate and controlled fire. There was a positive effect of manuring and chiseling on

soil bulk density, above –ground biomass, biomass N content, SOC, and N

sequestration and ecosystem pool. Organic matter can be restored to about 60 to

70% of natural levels with best farming practices. Improved management of

crop, grazing and forest lands is estimated to potentially offset 30,000 -60,000

million mt. of carbon released by fossil fuel combustion over the next 50 years

The balance between carbon additions of photosynthetic plant products to the

soil and their subsequent decomposition and microbial respiration determines

the amount of organic carbon present in the soil. Plant residues ,manure, sewage

sludge and other organic carbon by-products are the major sources of carbon

inputs in terrestrial ecosystem.

1.1 Terrestrial carbon sequestration Terrestrially carbon is stored in vegetation and in the soil. Plants store carbon

for as long as they live, in terms of live biomass. Once they die, the biomass

becomes a part of the food chain and eventually enters the soil as soil carbon. If

the biomass is incinerated, the carbon is reemitted into the atmosphere and is

free to move in the carbon cycle. On this basis, terrestrial carbon sequestration

has been classified into following type

1.1.1 Types of terrestrial carbon sequestration

Above ground biomass carbon sequestration The above ground biomass includes plants, animals and litter from these. The

proportion of carbon stored in these materials varies widely depending upon the

species. In general plants fix the carbon by consumption of carbon dioxide

through the photosynthesis mechanism. In this atmosphere carbon is converted

into plant biomass and retained within it until it decays. Woods of trees contain

about 25-48% carbon based on its dry weight. So forests have a huge potential in

carbon sequestration.

Below ground carbon sequestration

It includes carbon fixation by soil, soil microbes, etc. Carbon stocks in soil exceed

the carbon stocks in the vegetation by a factor of 2 to 5.The global soil hold twice

as much as carbon as the atmosphere (1400-1500 Gt C).The soil carbon pool

comprises two components. Soil and vegetation together exchanges

approximately 100 Gt C per year. In India the amount of carbon stored in the soil

is 23.4-27.1 Gt which is 1.6-1.8% of the global reserve.

It is therefore important to understand the dynamics of soil carbon as well its

terrestrial ecosystems carbon balance and the global carbon cycle. The loss of

soil organic carbon by conversion of natural vegetation to cultivated use is well

known.

1.2 CO2 Emissions from different sources

CO2 Emission:

CO2 has become the largest contributor among all anthropogenic greenhouse

gases to warming of the global climate [IPCC, 2002]. Developing countries

account for 73% of the global emissions growth rate in 2004. India is one of the

largest and fastest growing economies in South Asia and is emerging as a major

contributor to CO2 emissions among developing nations.

Sources of increased carbondioxide emissions:

.

Burning fossil fuels such as coal and petroleum is the leading cause of increased

anthropogenic CO2; deforestation is the second major cause. In 2008, 8.67

gigatonnes of carbon (31.8 of CO2) were released from fossil fuels worldwide,

compared to 6.14 gigatonnes in 199 gigatonnes0.Land use change contributed

1.20 gigatonnes in 2008, compared to 1.64 gigatonnes in 1990.This addition,

about 3% of annual natural emissions as of 1997, is sufficient to exceed the

balancing effect of sinks. As a result, carbon dioxide has gradually accumulated

in the atmosphere, and as of 2008, its concentration is 38% above pre-industrial

level.

2. OBJECTIVES

(a) To study the role of carbon sequestration in mitigating climate change

(b) To study carbon sequestration under different land use systems

3. REVIEW OF LITERATURE

The deforestation and conversion of tropical forest into agriculture ecosystem

result in emission of 1.6-1.7 Pg C / year into the atmosphere (IPCC, 2000). Forest

vegetation and soils contain about 1240 Pg of C (Dixon et.al., 1994) and the stock

varies widely among latitudes. Forests and soils have a large influence on

atmospheric levels of carbon dioxide (CO2) the most important global warming

gas emitted by human activities. Forest ecosystem can play a role in carbon

storage to reduce atmospheric carbon dioxide and forestry activities can prevent

climate change, by avoiding further emissions and by sequestering additional

carbon. Soil carbon storage is considered a viable option to mitigate climate

change (Lal, 2009). The global attention has been focused on agricultural soils

for the amelioration of increased atmospheric carbon dioxide (CO2) levels

through its sequestration in soils (IPCC, 2001).

Land use conversion from / into forest ecosystem can affect SOC stock to 1 m or

often to 2m depth. There is a strong need to develop and follow a standardized

sampling protocol for assessment of SOC stock and fluxes (Lal, 2009). Tropical

forest, are usually seen as a net carbon source because of the deforestation that

is taking place. However, recent evidences suggest that primary forests are not in

equilibrium, but may function as a net carbon sink. Available estimate suggest

that forest have a large mitigation potential. However, achieving the carbon

mitigation potential will require accurate methods to assess the carbon fluxes

and storage under alternative management regimes. Assessment of the potential

of soil C sequestration in forest ecosystem requires a systematic understanding

of the biogeochemical mechanism responsible for C stock and fluxes at the

molecular, aggregate, pedon, soil scape, land scape, regional and global scales. It

is necessary to understand the structure and dynamics of the belowground

component of terrestrial stocks.

The global organic carbon stock in the top 1m and 3 m of mineral soil has been

estimated to be 1500 Pg ( 1Pg = 1015 g ) and 2300 Pg respectively. Soil carbon

stock is determined mainly by the balance of the flow of carbon into the soil as

dead organic matter and of carbon output as heterotrophic respiration. Interest

in assessing the forest ecosystem with regards to climate change dates back only

to mid 1990’s as a potential strategy to off-set fossil fuel emission. There are

many factors and processes that determine the direction and rate of change in

SOC content when vegetation and soil management practices changed. SOC

storage can be increased by increasing the input rate of organic matter, changing

decomposability of organic matter, placing organic matter in deeper in the soil,

enhancing physical protection through either intra- aggregates/ organomineral

complexes.

The turnover rate of the different organic compounds varies due to the complex

interactions between biological, chemical and physical processes in soil (Post

and Kwon, 2000). Physical fractionation of soil emphasizes the role of soil

minerals and soil structure in SOC turnover and relates more directly to SOC

dynamics in situ than classical wet chemical SOC fractions. SOC is transformed by

bacterial action and stabilized in clay- / silt-sized organomineral complexes (HF-

OC) where majority of SOC is found. The highest concentrations of SOC are

associated with <5um mineral particles (Christensen 1996). The long term

increase of carbon represents accumulations of passive soil organic fractions,

which include charcoal and resistant compounds physically protected in

organomineral complexes (Schlesinger 1990). Soil bulk density is required to

calculate carbon/ organic matter concentrations. For the studies, where bulk

density values are not available, it is estimated by using the Adams (1973)

equation: BD = 100/(OM%/0.244)+(100-OM%/MBD), OM-Organic matter, MBD

– mineral bulk density (typical MBD = 1.64 (Mann 1986). There are many factors

and processes that determine the direction and rate of change in SOC content

when vegetation and soil management practices changed. SOC storage can be

increased by increasing the input rate of organic matter, changing

decomposability of organic matter, placing organic matter in deeper in the soil,

enhancing physical protection through either intra- aggregates/ organomineral

complexes (Post and Kwon 2000). US forest and crop lands currently fix about

250 and 75- 200 million mt of atmospheric C per year, respectively (Lal, 2009).

4. METHODOLOGY

The National Forest Library and Information Centre (NFLIC) at Forest Research

Institute, Dehradun and online search using the Internet was the first step taken

towards collection of data for the term paper. PDF files, e-books, web pages and

illustrative pictures were also obtained from the internet.

My guide Dr. C.M. Mathavan, Scientist-C also provided relevant and

sufficientdatawhich are of immense help for the completion of this term paper.

The library of Indian Institute of Remote sensing (IIRS), Kali Das Road, Dehradun

is also another important source for obtaining the required materials and data

for my term paper.

Materials were also collected from friends who have the relevant data for my

topic of interest.

5. GLOBAL CARBON SINK CONCEPT

Global carbon is held in a variety of different stocks. Natural stocks include

oceans, fossil fuel deposits, the terrestrial system and the atmosphere. In the

terrestrial system carbon is sequestered in rocks and sediments, in swamps,

wetlands and forests, and in the soils of forests, grasslands and agriculture.

About two-thirds of the globe’s terrestrial carbon, exclusive of that sequestered

in rocks and sediments, is sequestered in the standing forests, forest under-

storey plants, leaf and forest debris, and in forest soils. In addition, there are

some non-natural stocks. For example, long-lived wood products and waste

dumps constitute a separate human-created carbon stock. Given increased

global timber harvests and manufactured wood products over the past several

decades, these carbon stocks are likely increasing as the carbon sequestered in

long-lived wood products and waste dumps is probably expanding.

A stock that is taking-up carbon is called a "sink." A sink is also defined as a

process or an activity that removes greenhouse gases from the atmosphere and

the stock that is releasing carbon is call a "source." Shifts or flows of carbon

over time from one stock to another, for example, from the atmosphere to the

forest, are viewed as carbon "fluxes." Over time, carbon may be transferred

from one stock to another.

Fossil fuel burning, for example, shifts carbon from fossil fuel deposits to the

atmospheric stock. Physical processes also gradually convert some

atmospheric carbon into the ocean stock. Biological growth involves the

shifting of carbon from one stock to another. Plants fix atmospheric carbon in

cell tissues as they grow, thereby transforming carbon from the atmosphere to

the biotic system. The amount of carbon stored in any stock may be large, even

as the changes in that stock, fluxes, are small or zero.

An old-growth forest which is experiencing little net growth would have this

property. Also the stock may be small while the fluxes may be significant.

Young fast-growing forests tend to be of this type. The potential for

agricultural crops and grasses to act as a sink and sequester carbon appears to

be limited, due to their short life and limited biomass accumulations. Their role

for human management of carbon could increase as we learn more about their

potential.

6. INDIAN SCENARIO OF TERRESTRIAL CARBON SEQUESTRATION

UNDER VARIOUS LAND USE SYSTEMS

6.1 Land Use and Soil Resources of India: The total geographical area of India is 328.7 million hectares (Mha) or about

2.5% of the total land area of the world (Table 1). It is home to 1.1 billion or

16% of the world population. India is the second most populous and densely

populated country in the world. Principal land uses include 161.8 Mha of

arable land (11.8% of the world) of which 57.0 Mha (21.3% of the world) is

irrigated, 68.5 Mha of forest and woodland (1.6% of the world), 11.05 Mha of

permanent pasture (0.3% of the world) and 7.95 Mha of permanent crops

(6.0% of the world).

The large land base, similar to that of the U.S.A. and China or Australia, has a

potential to sequester C and enhance productivity while improving

environment quality. The Green Revolution of the 1970s needs to be revisited

to enhance production once again and to address environment issues of the

21st century including climate change.

7. LAND USE CHANGES & SOIL CARBON SEQUESTRATION

When agricultural land is no longer used for cultivation and allowed to revert

to natural vegetation or replanted to perennial vegetation soil organic carbon

can accumulate by processes that essentially reverse some of the effects

responsible for soil organic carbon losses from when the land was converted

from perennial vegetation. Soil organic matter enhances soil carbon

sequestration with changes in land-use and soil management.

There is a large amount of variation in rates and the length of time that carbon

may accumulate in soil that are related to the productivity of the recovering

vegetation, physical and biological conditions in the soil, and the past history of

soil organic carbon inputs and physical disturbance. Maximum rates of C

accumulation during the early aggrading stage of perennial vegetation growth,

while substantial, are usually much less than 100 g C / m2/y. Average rates of

accumulation are similar for forest or grassland establishment: 33.8 g C/m2/y

and 33.2 g C /m2/y respectively.

These observed rates of soil organic C accumulation, when combined with the

small amount of land area involved, are insufficient to account for a significant

fraction of the missing C in the global carbon cycle as accumulating in the soils

of formerly agricultural land.

Table:1

Table:2

8. CARBON SEQUESTRATION POTENTIAL OF VARIOUS TERRESTRIAL ECOSYSTEMS

8.1 Forest ecosystems: CO2 emission and C sequestration in soils Forest ecosystems covering about 4.1 billion hectares globally are a major

reserve of terrestrial C Stock. Carbon storage in forest ecosystem involves

numerous components including biomass C and soil C. Forest vegetation and

soils constitute a major terrestrial carbon pool with the potential to adsorb and

store carbon dioxide (CO2) from the atmosphere. Because of the large areas

involved at regional / global scale, forest ecosystem play a vital role in carbon

storage; capture and release large amounts of carbon and have the capacity to

influence atmospheric carbon dioxide concentration and climate dynamics.

Evidence of climate change linked to human induced increase in green house gas

(GHG) concentration is well-documented in international studies. Soil carbon is

the largest C pools in the world’s forest ecosystem with almost 700 Gt with

substantial CO2 comes from mineralization and decomposition of organic matter

and respiration of roots and soil organisms. On the other hand the total

aboveground forest C stock in the biosphere is estimated to be around 320-360

Gt. Measurement of CO2 flux has been considered as a reliable and sensitive

indicator of C cycling. Even a small change in the magnitude of soil CO2 flux can

influence CO2 levels in the atmosphere to the great extent.

Forest ecosystem contain more carbon per unit area than any other land use

type, and their soils – which contain around 40 percent of the total carbon - are

of major importance when considering forest management. Normally, soil

carbon is in steady-state equilibrium in natural forest, but as soon as

deforestation (or a forestation) occurs, the equilibrium will be affected. It is

presently estimated that 15 to 17 million ha/year are being deforested, mainly in

the tropics (FAO, 1993 C storage and release by forest ecosystems (through

afforestation, reforestation or deforestation). Therefore, where deforestation

cannot be stopped, proper management is necessary to minimise carbon losses.

Afforestation, particularly on degraded soils with low organic matter contents,

will be an important way of long-term carbon sequestration both in biomass and

in the soil

8.2 Grasslands Grasslands like forest play an important role in carbon sequestration. Firstly

grasslands occupy billions of hectares (3.2 according to FAO) and they store from

200 to 420 Pg in the total ecosystem, a large part of this being below the surface

and therefore in a relatively stable state. Soil carbon amounts under grassland are

estimated at 70 t ha-1, similar to the quantities stored in forest soils. Owing to the

unreliability of the data, FAO land use statistics no longer give the area of

grasslands. Many grassland areas in tropical zones and dry lands are badly

managed and degraded; these offer a range of carbon sequestration possibilities.

8.3 Cultivated lands The development of agriculture has involved a large loss of soil organic matter.

There are various ways in which different land management practices can be used

to increase soil organic matter content such as increasing the productivity and

biomass (varieties, fertilisation and irrigation). Global climatic change may have a

similar effect. Sources of OM also include organic residues, composts and cover

crops. The main ways to achieve an increase in organic matter in the soil are

through conservation agriculture, involving minimum or zero tillage and a largely

continuous protective cover of living or dead vegetal material on the soil surface.

Carbon sequestration and an increase in soil organic matter will have a direct

positive impact on soil quality and fertility. There will also be major positive

effects on the environment, and on the resilience and sustainability of agriculture.

9. CONSEQUENCES

9.1 Soil quality and fertility Organic matter has essential biological, physical and chemical functions in soils.

OM content is generally considered one of the primary indicators of soil quality,

both for agriculture and for environmental functions. Organic matter is of

particular interest for tropical soils (except for vertisols) with low -activity clays,

i.e. having a very low cation exchange capacity. Cation exchange capacity increases

in function of the increase in organic matter (Figure below). Bioavailability of

other important elements, such as phosphorus, will be improved and the toxicity

of others can be inhibited by the formation of chelate or other bonds, for example,

aluminium and OM. In agriculture with low plant nutrient inputs, recycling of

nutrients (N, P, K, Ca) by gradual decomposition of plant and crop residues is of

crucial importance for sustainability.

9.2 Environmental impacts

Carbon sequestration in agricultural soils counteracts desertification process

through the role of increased soil organic matter in structural stability (resistance

to both wind and water erosion) and water retention, and the essential role of soil

surface cover by plant, plant debris or mulch in preventing erosion and increasing

water conservation. OM, which increases the soil quality, also protects through

fixation of pollutants (both organic, such as pesticides, and mineral, such as heavy

metals or aluminium) with, in general, a decrease in their toxicity. Air quality is

mainly concerned with the decrease in atmospheric CO2 concentration. The main

soil factor controlling their genesis is anaerobiosis (soil reduction), which is

generally linked with hydromorphy. When pastures or rangelands are increased,

the methane emission by cattle has to be taken into account. In some

environments and depending on climatic conditions (humid area) or soil

properties (high clay content), N2O can be formed. Hence careful balance of the

different gas emissions has to be made. Wetland rice culture represents the most

complex system in relation to carbon sequestration.

9.3 Biodiversity and soil biological functioning Changes in biodiversity are evident when deforestation occurs. For afforestation,

they will depend on the forest type established. Well-managed agroforestry

systems also involve a wide range of biodiversity. Generally mammal biodiversity

is preserved in reference to forests, but the numbers of bird species are halved and

plant species decrease by a third (420 to 300), (IPCC, 2000. Most intensive

agriculture systems have in the past led to a strong decrease in biodiversity,

parallel to the decrease in organic matter mainly through tillage and pesticide use.

For croplands the increase in biodiversity in relation to the increase in organic matter

concerns mainly the soil biodiversity. Figure above presents a hierarchical organization

of soil biodiversity which depends directly on the input of fresh OM and the agronomic

practices. This biodiversity ranges from genes to micro-organisms, fauna, and above

ground biodiversity. The amount of bacteria can increase by several orders of magnitude

from 103 to 1012, as soon as the source of OM is abundant.

9.4 Benefits for farmers

Farmers are not always sensitive to soil quality, unless there are other more tangible

advantages. Soil conservation and prevention of land degradation are increasingly

perceived as concrete benefits. Soil organic matter is also equivalent to a certain amount

of nutrients and will retain supplementary water. As regards conservation tillage and no-

tillage, farmers can gain in terms of working time, energy and costs of materials: these

are direct advantages that can be evaluated. Farmers will have to control pests in any

case, but with higher soil quality, crops will generally be in better health and more

resilient. Well-managed agroforestry systems can be viable from an economic point of

view. Some examples are well known, such as coffee, cacao, pepper, fruit trees or

palms. These systems present advantages, but there will not always be immediate

increases in yields, especially for normal crops.

9.5 Effects of climatic change While an increased content of atmospheric greenhouse gases is leading to climatic

change, numerous complex, contrasting and reverse effects will occur. An increase

in CO2 concentration in the atmosphere induces an increase in biomass or in the

Net Primary Production (NPP) by carbon fertilization, playing a major role in plant

photosynthesis and growth. The gain in CO2 fixation could be important. The

increase in productivity measured for a doubling of the CO2 concentration

(predicted for the year 2100) is about 30 percent for C3 plants. Another important

effect of CO2 increase is a decrease in transpiration from the stomata which results

in increased water use efficiency (WUE), particularly in C4 plants.

So far as water is concerned, the net effect of CO2 on the reduction of plant

transpiration is favourable. Evidently in order to achieve an increase in yield in the

field, other plants needs have to be met in the normal way including available

water and nutrients.

As far as the carbon cycle is concerned there will be an increase in C sequestration

by the aboveground biomass and a correlated increase in carbon input to the soil

from plant residues and from the growth and decay of fine roots. The compounds

of roots have a higher C/N ratio and are more stable. With regard to soil C

sequestration, another factor, which will play an important role, is temperature,

which may increase over part of the globe. Such an increase could provoke a

higher rate of OM mineralization by microbes and a higher respiration rate by

roots.

Terrestrial sequestration can play a significant role in addressing the increase of

CO2 in the atmosphere.

Terrestrial sequestration represents a set of technically and commercially viable

technological measures that have the capability to reduce the rate of CO2 increase

in the atmosphere. Tree planting, forest management, and conservation tillage

practices are such measures to increase the sequestration of carbon in plants and

soils.

Changes in cropping systems can reduce annual emissions of trace GHGs and

enhanced forest management and conversion to durable wood products provide a

mechanism to allow forests to continually sequester carbon.

Soil organic matter (SOM) forms the major reservoir of carbon. It is a key

determinant of carbon & nutrient cycling in the biosphere.

Agricultural practices typically deplete soil C because harvesting removes major

fraction of photosynthetically fixed C, and therefore, least amount of plant litter is

returned to the soil.

Terrestrial sequestration activities can provide a positive force for improving

landscape-level land management. Land-use practices and land conversion such as

afforestation, forest restoration, and improved forest and agricultural

management are such activities.

It can provide significant benefits to society, such as improvements in wildlife and

fisheries habitat, enhanced soil productivity, reduction in soil erosion, and

improved water quality.

Realizing the opportunities to sequester carbon in terrestrial systems will require

managing resources in new ways that integrate crosscutting technologies and

practices.

Cropland management practices can increase the amount of carbon stored in

agricultural soils by increasing plant biomass inputs or reducing the rate of loss of

soil organic matter to the atmosphere as CO2. Conversion of marginal croplands to

other less intensive land uses to conservation reserve and buffer areas.

Precision agriculture can be adapted for improving soil carbon sequestration

through a customized carbon sequestering management plan.

Some priorities can be defined for degraded lands with adapted measures for

croplands, pastures and agroforestry. Development of conservation agriculture

will be the key. It will be easier to develop conservation agriculture for crops in

developing countries because of the severity of land degradation in these regions.

Improvement of degraded pastures and the expansion of agroforestry will need

more effort and more time. Conservation of highly vegetated areas can enhance

carbon capture and thus help in reduction of atmospheric co2.

10. CONCLUSION

There is a growing concern that increasing levels of CO2 in the atmospheres will

change the climate making earth warmer and increasing the extremes weather

events. Global precipitation will increase due to increased evaporation from the

oceans, but some areas will receive substantially less rainfall than today. Nights

and winters are expected to warm more than day time and summer temperature.

Agriculture would be faced with a longer and drier growing season. The soil

organic matter content may decline, increasing risks of soil compaction and

erosion and decreasing plant available water capacity. One solution for this global

problem is to sequester carbon from atmosphere with soil and vegetation (sinks).

Increased long term (20-50 year) sequestration of carbon in soils, plants and plant

products will benefit the environment and agriculture. Crop, grazing and forest

lands can be managed for both economic productivity and carbon sequestration. In

many settings, this dual management approach can be achieved by applying

currently recognized best management practices such as conservation tillage,

cover crops, efficient nutrient management, erosion control and restoration

degraded lands. In addition, conversion of marginal arable land and waste lands to

forest / grass land can rapidly increase soil carbon sequestration. One way to think

of soil carbon is as a commodity.

The development of agriculture during the past centuries and decades has entailed

consumption of soil carbon stocks created during a long-term evolution. In most of

cultivated lands this has led to reduced land productivity due to land degradation

and desertification. It is time now to reverse this trend. This will be feasible only if

the type of agriculture is changed.

There are also knowledge and data gaps associated with practically all the

regional and global extrapolations underpinning the quantitative analysis, as well

as problems in measuring and interpreting field data on carbon fluxes. The

attention of Governments needs to be drawn to these potential benefits and the

need to initiate a process for data collection and analysis of carbon stock and

fluxes under different selected sites on a pilot scale.

There is a need to understand the carbon (C) sequestration potential of the

forestry option and its financial implications for each country. At the same time, it

is important to recognize that carbon sequestered in trees and soils can be

released back to the atmosphere, and that there is a finite amount of carbon that

can ultimately be sequestered. Practices that aim to reduce carbon losses and

increase sequestration generally enhance the quality of soil, water, air and wildlife

habitat. Tree planting that restores fuller forest cover may not only sequester

carbon but could improve habitat suitability for wildlife. Preserving threatened

tropical forests may avoid losses in both carbon and biodiversity, absent any

leakage effects.

Carbon sequestration rates vary by tree species, soil type, regional climate, and

topography and management practice and are less well documented but

information and research in this area is growing rapidly. Statistical sampling,

computer modeling and remote sensing can be used to estimate carbon

sequestration and emission sources at the global, national and local scales. Current

forest carbon estimates are generally more accurate and easier to generate than

soil estimates. To assess the potential of carbon sequestration by forest

management as part of climate change mitigation strategies, it is necessary to

understand the carbon storage in forest biomass, soil and wood products, and the

interactions between these compartments.

Benefits include soil quality improvement, increase in inputs use efficiency,

erosion control, decrease in non-point source pollution and low rate of anoxia and

hypoxia in coastal ecosystems. Global food security cannot be achieved without

restoring the quality of degraded soils, for which soil carbon sequestration is an

essential prerequisite. It mitigates climate change by offsetting anthropogenic

emissions; improves the environment, especially the quality of water; enhances

soil quality; improves agronomic productivity; and advances food security. It is

low-hanging fruit and a bridge to the future unit carbon- neutral fuel sources and

low – carbon economy take effect.

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