Deforestation, mainly in the tropics, averaging more than 13 million hectares (ha) per
year during 1980 to 1995 (1), was responsible for 20% (2) to 25% of
global, anthropogenic green house gas emissions during the 1990s (3). In absence of
mitigation policies, the probability interval for 1990 to 2100 warming is
1.70 to 4.90 degrees Celsius (4), forcing us to find ways to reduce emissions (5).
Now that the inclusion of Land Use, Land-Use Change and
Forestry (LULUCF) as a credit-earning climate change mitigation option has
been taken positively in favor of the afforestation and reforestation for
the first 5-year commitment of the Kyoto Protocol (2008-2012) (6), it
may be useful for nations to invest in actions that not only have the
potential to sequester carbon but also to provide livelihood security to poor
people in developing countries, help reduce the rate of deforestation,
and contribute to sustainability. Agroforestry and trees outside forests
offer an immediate option. Such areas indeed may be acting as the "missing
sinks."
This is particularly important because the Clean Development Mechanism
will allow afforestation and reforestation projects but exclude all other
project types, including those addressing tropical deforestation. This may
provide some crediting opportunities for agrofrestry projects, depending
on how the rules are written.
Trees outside forests in agroecosystems are an important resource
providing products and services to society (7). For example, India is
estimated to have between 14,224 million (8) and 24,602 million such trees (9),
spread over an equivalent area of 17 million ha (10), annually contributing to 98 million tonnes (49% of total 201
million tonnes) of fuel wood, and 31 million cubic meters (out of 64 million cubic meters) of timber requirement in the country (11). This also brings income and well-
being to those who practice tree-growing.
Such systems include a variety of local forest management practices
(12) where sometimes trees may be retained for up to 300 years (13).
The amount of time a carbon sink is retained is an important consideration for
designing strategies to manage carbon storage (14). Agroforestry
encompasses a wide variety of practices, including trees on farm
boundaries, trees grown in close association with village rainwater
harvesting ponds, crop-fallow rotations, a variety of agroforests,
silvopastoral systems, and trees in urban settlements (15). Agroforestry
is practiced globally, but it is widespread in the tropics. Approximately
1.2 billion people (20% of the world’s population) depend directly
on agroforestry products and services in developing countries (16). The
practitioners are also among the world’s poorest.
Agroforestry practices have the potential to store carbon and
remove atmospheric carbon dioxide through augmented growth of trees
and shrubs. It has been found promising for carbon sequestration in India
(17), Mexico (18), the former Soviet Union (19), Canada (20), and sub-Saharan
Africa (21) among others. It also has strong implications for sustainable
development because of the interconnection with food production, rural
poverty, and associated consequences for the environment. Agroforestry may
provide a viable combination of carbon storage with minimal effects on
food production. Policies that promote agroforestry will help
increase the carbon density of sites relative to traditional agriculture,
thereby providing climate change mitigation benefits (3).
For example, agricultural activities occurring on approximately half
of the land in the contiguous U.S. provide much of the opportunity to
store carbon through afforestation on farms and ranches (22). Carbon
sequestration in Indian agroforests varies from 19.56 tonnes of carbon per ha per year (tC ha-1yr-1) in north
Indian State of UP (17) to a carbon pool of 23.46 to 47.36 tC ha-1
above and below ground in tree-bearing arid agroecosystems of Rajasthan.
The average sequestration potential in agroforestry has been estimated to be
25 tC ha-1 over 96 million ha of land in India, and 6 to 15 tC ha-1 over
75.9 million ha in China (23). Estimates for global potential for
mitigation action through improved management are
between 400 million ha in agroforestry and 1300 million ha in croplands (3) to a gross
1895 million ha in Asia, Africa, and Latin America (24).
In general, agroforestry can sequester carbon at time-averaged rates
of 0.2 to 3.1 tC ha–1 yr-1(3). In temperate areas, the potential carbon
storage with agroforestry ranges from 15 to 198 tC ha-1 (25), with a modal
value of 34 tC ha-1 (3, 26). Estimates indicate that agroforestry can
sequester 7 GtC between 1995 and 2050 globally at a total cost of US$ 30 billion
(23), but these estimates are conservative in view of the
area, observed rates, and gaps in our understanding. Better estimates can
only be known after country-to-country studies become available. The
associated impacts of agroforestry include helping to attain food security
and secure land tenure in developing countries, increasing farm income,
restoring and maintaining above-ground and below-ground biodiversity
(including corridors between protected forests), serving as CH4 sinks,
maintaining watershed hydrology, and decreasing soil erosion (3).
Agroforestry offers a cost-effective option available in developing
countries, such as India, that have large potential. The cost of mitigation in the
case of agroforestry may be between US$ 1.6/tC in India and US$ 16.3/tC in
China. However, rates are often below US$ 6/tC, making tree-growing a cost-effective option (23).
Agroforestry can also mitigate the demand of wood globally thereby
reducing pressure on unmanaged old-growth or mature secondary forests.
Intensive harvest of mature forests and/or conversion of mature forests to
younger forest stands typically leads to significant carbon losses (27).
Agroforestry systems have less biodiversity compared with forests, but they
can also act as an effective buffer to deforestation and conversion of
forest lands to other land uses, which threaten forests (28). Trees in
agroecosystems also support threatened cavity nesting birds and offer forage
and habitat to many species of birds (29). It also leads to a more
diversified and sustainable production system than many treeless farming
alternatives and provides increased social, economic, and environmental
benefits for land users at all levels (3). If sustainable small-farm
agriculture in developing countries is beneficial to farmers, it can
contribute to future food security (30).
Agroforestry systems can be better than other land uses at the
global, regional, watershed, and farm scales because they optimize food
production, poverty alleviation, and environmental conservation (3). For
instance, promotion of species used in the woodcarving industry has three
advantages: it facilitates long term locking-up of carbon in carved wood
coupled with the creation of new sequestration potential through intensified
tree-growing; supports local knowledge on woodcarving and tree-growing,
thereby strengthening livelihood security; and helps the trade and
industry. These processes are expected to lead to the flow of benefits of
globalization to those affected most by it. The unique combination of
potential benefits to individual farmers at a local level and environmental
benefits at a global level make agroforestry a suitable option.
Existing trees in agroecosystems may be contributing to substantial
sequestration of carbon (8). Some studies have argued that emission rates
of CO2 from the combustion of fossil fuel have increased almost 40% in
the past 20 years, but the amount of CO2 accumulating in the atmosphere
has remained the same or even declined slightly (31). This may not be
accepted in light of long-term data collected at Mauna Loa mountains
in Hawaii showing a steady increase in atmospheric CO2 mean concentration of
approximately 316 parts per million by volume (ppmv) in 1958 to
approximately 369 ppmv in 1998 (31a). Whatever the case, it has been
suggested that much of this carbon has gone into the organic matter of
forests that is not often reported in forest inventories (31). For
example, more than 75% of the carbon sequestered in the United
States is found in organic matter that is not inventoried (32).
Agroforestry could as well be the missing sinks.
It can be suggested that forest organic matter is not the only place
to look for missing carbon and that some of this missing carbon
may also have gone into the missing sinks—-the tree-bearing
farmlands—-globally. Support for this inference may be seen in recent
findings (33) that Asia seems to be “another place to
look for forest carbon sinks” (31). Additionally, 1400 million ha of
croplands and agroecosystems may be providing ecosystem services worth US$
92 ha-1 yr-1 as pollination, biological control, and food production
amounting to a total of US$ 128 billion per year at 1994 prices (34).
Agroecosystems are also an essential component of developmental intervention
for rural livelihood in developing countries (35, 36).
Negotiators will meet at Marrakech in October 2001 to decide
modalities for afforestation and reforestation projects under Article 12
of the Kyoto Protocol in the first commitment period, taking into account the
issues of non-permanence, additionality, leakage, uncertainties, and socio
-economic and environmental impacts (37). Adoption of rules and modalities
should make sure to provide crediting for reforestation/afforestation
projects that create agroforestry systems.
Asia is also rich in agroforestry and local forest management
practices. The obvious next step is the establishment of clear policies and programs globally
to sustain the existing agroforest carbon pool, extend and enhance the productivity
of the existing pool, establish new pools, and lock up carbon for the long-term
in wood products. There is a need to support local
forest management practices through the development of suitable policies,
assisted by robust country-wide scientific studies aimed at a better
understanding about the potential of agroforests for climate change mitigation
and human well-being.
References and Notes
1. Food and Agriculture Organization (FAO), State of the World's Forests
(FAO, United Nations, Rome, Italy, 1997).
2. Wulf Killmann, Forestry and Climate Change after CoP6. FAO Advisory
Committee on Paper and Wood Products, Food and Agriculture Organization
(FAO, United Nations, Rome Italy, 2001).
3. R. T. Watson et al., Land Use, Land-Use Change and Forestry (IPCC
Special Report, Cambridge Univ. Press, Cambridge, 2000), 388 pp. Available
at www.grida.no/climate/ipcc/land_use/index.htm. See also references cited
therein.
4. T.M.L. Wigley, S.C.B. Raper, Science 293, 451 (2001).
5. R. Bonnie et al., Science 288, 1763 (2000).
6. UNFCC, Decision 5/CP.6: Implementation of the Buenos Aires Plan of
Action, (2001) Available at
http://www.unfcc.int/cop6_2/documents/dec5cp6uneditedvers.pdf
7. C. Kleinn, Unasylva 200, 3 (2000).
8. N.H. Ravindranath, D.O. Hall, Biomass, Energy and Environment—a
Developing Country Perspective from India. (Oxford University Press, New
York, NY, USA, 1995).
9. Ram Prasad et al., Trees Outside Forests in India: A National
Assessment (Indian Institute of Forest Management, Bhopal, India, 2000)
10. GOI, National Forestry Action Programme. Government of India, Ministry
of Environment and Forests, New Delhi. vol. 1 & 2, and Summary (1999).
11. S.N. Rai, S.K. Chakrabarti, Indian Forester 127, 263 (2001).
12. D. N. Pandey, Ethnoforestry: Local Knowledge for Sustainable Forestry
and Livelihood Security (Himanshu/AFN, New Delhi, 1998); D.N. Pandey,
Beyond Vanishing Woods: Participatory Survival Options for Wildlife,
Forests and People (Himanshu/CSD, New Delhi, 2ed. pp. 222, 1996).
13. D.N. Pandey, Indian Forester 118, 305 (1992) and Indian Forester 119,
521 (1993).
14. Inez Fung, Science 290, 1313 (2000).
15. P. Huxley, Tropical Agroforestry (Blackwell Science Publishers,
London, United Kingdom, 1999).
16. R.R.B. Leakey, P.A. Sanchez, Agroforestry Today 9(3), 4 (1997).
17. T.P. Singh et al., Indian Forester 126,1257 (2000).
18. Ben H.J.De Jong et al., Mitigation and Adaptation Strategies for
Global Change 2, 231 (1997).
19. T.P. Kolchugina, T.S. Vinson, Mitigation and Adaptation Strategies for
Global Change 1,197 (1996).
20. G. Stinson, B. Freedman, Mitigation and Adaptation Strategies for
Global Change 6, 1 (2001).
21. J.D. Unruh et al., Climate Research, 3, 39 (1993)
22. NAC (United States Department of Agriculture National Agroforestry
Center). Working Trees for Carbon Cycle Balance/Agroforestry: Using trees
and shrubs to produce social, economic, and conservation benefits. (Gary
Kuhn, USDA NAC East Campus - UNL, Lincoln, 2000) available at
http://www.unl.edu/nac
23. J.A. Sathaye, N.H. Ravindranath, Annu. Rev. Energy Environ 23, 387
(1998).
24. J.T. Houghton et al., Global Biogeochem. Cycles 7, 305.
25. R.K. Dixon et al., Climate Change 30, 1 (1994).
26. R.K. Dixon, et al., Global Environmental Change 3, 159 (1993).
27. Ernst-Detlef Schulze et al., Science 289, 2058 (2000).
28. Ian R. Noble, Rodolfo Dirzo, Science 277, 522 (1997).
29. D.N. Pandey, D. Mohan, J. Bombay nat. Hist Soc. 90, 58 (1993); D.N.
Pandey, J. Bombay nat. 88, 285 (1991) and 88, 458 (1991).
30. I. Serageldin, Science 285, 387 (1999).
31. S.C. Wofsy, Science 292, 2261 (2001).
31a. UNEP/GRID-Arendal, CO2 Concentration in the atmosphere: Mauna Loa
Curve (2001) available at http://www.grida.no/climate/vital/06.htm
32. S.W. Pacala et al., Science 292 2316 (2001).
33. J. Fang et al., Science 292, 2320 (2001).
34. R. Costanza et al., Nature 387, 253 (1997).
35. A.B. Mathur, D.N. Pandey, J. Soc. Ind. For. 32 (3), 9 (1994).
36. D.S. Ravindran, T.H. Thomas, International Forestry Review 2, 182
(2000).
37. UNFCCC/CP/2001/L.11 Draft Decision CP.6 (2001) available at
http://www.unfccc.int/resource/docs/cop6secpart/l11.pdf
38. I am grateful for the valuable comments on the draft by Robert Bonnie
and D.S. Ravindran. Support of the IIFM, Bhopal is acknowledged.
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