Although expanding the area of forest generates many environmental and socioeconomic benefits for society, it generally comes at the cost of forgone opportunities for other activities, especially agriculture. Social impacts can include population displacement and loss by some section of society, but the net effect of land-use change on employment, income, and equity cannot generally be determined a priori: It must be evaluated on a case-by-case basis, with specific social conditions in each country taken into account in assessing overall impact. In principle, the decision to limit deforestation carries opportunity costs as well because it entails forgoing other potential land uses, such as agriculture. In many developed countries with agricultural surpluses-notably in Europe-or relatively abundant marginal agricultural land (e.g., the United States), there is considerable scope for increased afforestation on agricultural land with relatively little adverse effect on agricultural production, employment, or economic well-being.
Several studies in the United States have examined the scope of afforestation
of agricultural land for carbon sequestration. Some of these studies (e.g.,
Moulton and Richards, 1990; Parks and Hardie, 1995; Stavins, 1999) have ignored
the effects of afforestation on land markets and thereby on the agricultural
sector. A study by Adams et al. (1993) found that large-scale afforestation
programs in the United States could have potentially sizable impacts on the
agricultural sector by diverting land from agriculture and increasing agricultural
prices. Alig et al. (1997) developed an integrated model of the forest
and agricultural sectors of the U.S. economy and used this model to assess the
likely impact of a fairly crude afforestation program with limited long-term
incentives. They found that much of the land converted from agriculture to forests
could be offset simply by converting other land from forestry to agriculture
to maintain equilibrium in the land market. Although this forest-to-agriculture
conversion reduces the social cost of afforestation programs, it also reduces
their carbon sequestration potential.
Adams et al. (1999) demonstrated that the scope and timing of forest-based carbon sequestration activities have important effects on the social costs of the policy and the intersectoral impacts between forestry and agriculture. Their study suggested that carbon sequestration activities within existing land uses under Article 3.4 (e.g., changes in forest management) would induce less intersectoral spillover between the forest and agricultural sectors than would land-use change activities under Article 3.3.
In the tropics, afforestation could enhance or impoverish local agriculture and increase or decrease employment and wealth, depending on specific circumstances. On one hand, some of the biomass from new plantations could provide green manure, fodder, or fuelwood, which releases cow dung and crop residues to be incorporated into the soil. This biomass could increase overall agricultural production and reduce the pressure on natural forests (Ravindranath and Hall, 1995). Plantations can also provide employment, especially if they are organized through partnerships with local communities and if there are opportunities for the utilization of non-timber forest products (Indonesian First National Communication, 1999; TERI, 1999).
On the other hand, new plantations may take fertile land of high value from vulnerable groups, such as small farmers and landless rural people. Conversion of such land to forests could threaten the livelihoods of local groups, increase poverty, and perhaps accelerate deforestation elsewhere. The use of agroforestry may often provide a viable combination of carbon storage with the least effects on the food production capacity of the land. The inclusion of trees will typically increase the carbon density of sites relative to traditional agriculture, thereby providing climate change mitigation benefits. Agroforestry has also been demonstrated to produce many of the other environmental benefits of forests, however, as well as diversifying the income base of the individuals practicing it. Conversion of degraded croplands that are typical of smallholder farming in sub-Saharan Africa into agroforests has major positive impact on carbon storage, but it has also become key to food security and a way out of poverty for millions of African farmers (Sanchez et al., 1997a,b; Sanchez, 2000).
Not only can changes in agricultural and agroforestry practices directly enhance carbon storage in soils, improvements in these practices on the forest margin can reduce deforestation pressure and corresponding emissions of carbon. The net effect of changes in agricultural practices on deforestation, however, may depend on the relative input intensity of the technologies that are applied. Capital and land-intensive technologies on the forest margin may further the rate of deforestation; labor-intensive technologies are less likely to do so.
Forests are valued for many goods and services, as reflected in recent forest
policy and institutional changes in many countries. In contrast, carbon is a
single commodity, and any form of carbon in trees and soils will suffice as
long as it is securely stored. Promotion of carbon over other forest values
could impoverish people who benefit from the diversity of products and non-carbon
services. This problem will be greatest where livelihoods are at stake, especially
where food security is threatened (Ogle, 1995), as well as where the interests
of forest-dependent people are poorly represented (Tipper and de Jong, 1998).
This factor is particularly important in countries with low per capita incomes
that are not self-sufficient in terms of growing food and have a low capacity
to finance food imports.
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