Dry forests

By IuCn

Masumi Gudka and Jonathan Davies, International Union for the Conservation of Nature

Asingle tree in a dryland landscape can hold as much importance to the survival of an entire dryland ecosystem as a patch of forest can in a humid landscape. A few individual trees are often the pillars to the survival of many of the inhabitants and ecosystems in the drylands. In some indigenous communities in dry regions of the world, one tree is owned by several families, signifying the high value placed on this resource. Usually, a tree is the link to a plethora of biodiversity, becoming an ecosystem in itself.

Dryland trees are the key ingredient in supporting the environmental processes and social functions found in the mosaic of habitats and ecosystems that collectively make up the dryland areas. But the trees in drylands often do not reach above 5 meters, one of the criteria defining forests. As a result, extensive tree clusters in the drylands are invisible on forest maps because they fall outside the typical forest definition. Consequently, dryland forests have been largely disregarded as important ecosystems—even if they account for 42 percent of all tropical forests.

Dryland trees can be sparse, but tree density and height can also be comparatively high. Irrespective of their densities and heights, dryland trees and dry forests play important, but often underestimated, roles in dryland livelihoods and ecosystems. How drylands are defined also varies among organizations and governing bodies, which affects how and where their development is addressed. For our purposes, “drylands” encompass not only dry subhumid, semiarid and arid areas, but the hyperarid areas. In short, it includes all dry areas and deserts.

Deserts are ecosystems in their own right, with highly specialized cultures and biodiversity that are unique to them. The misconception that deserts are wastelands and should be “restored” to a state similar to humid forests inadvertently leads to their degradation, for instance, by planting of alien invasive species to “green” the drylands. However, man-made deserts, like those of Inner Mongolia, which were once productive areas in the days of the great Genghis Khan, can and need to be restored. The term desertification is also misleading because it conjures up images of increasing or advancing deserts. In reality, desertification is the process of land degradation in the drylands, which leads to the loss of productivity.

The cases highlighted in this magazine highlight many ways to control desertification using soft technologies, like the tree planting in China’s Future Forests Programme or FADE’s sand fixing of desert dunes in Nigeria.

Desertification can also be tackled through effective land use planning and sustainable natural resource management by local communities. It is crucial to encourage governments to support bottom-up mechanisms to reverse or mitigate land degradation and incorporate these mechanisms into policy and governance systems.

Sustainable management and restoration of dry forests contributes greatly to overcoming the challenges of desertification, land degradation, and drought. In many drylands, forests protect the water towers and riparian zones that are pivotal for ecosystem function. Dry forests also provide essential seasonal safety nets—sources of secondary income and grazing reserves—for dryland residents. Restoring and sustainably managing these zones reduces the risk of drought, increases ecosystem resilience, and strengthens adaptive capacities.

Forest management in the drylands depends heavily on local land management practices, which have been shown to play a role in conservation, but which in many cases are growing weaker or being abandoned. Dryland trees are conserved through agroforestry, farm fallow practices, pastoralism, and through community protection of sacred sites and forest patches of economic significance. The preservation of abundant biodiversity and traditional cultures in dryland areas is inextricably linked to the availability and use of indigenous trees.

Indigenous and community-conserved areas (ICCAs) widely conserve dryland ecosystems and habitats. There is no clear idea of the number or size of ICCAs across the world, although an estimated 420 million hectares of forests, or 11 percent of the world’s total, are under community ownership or administration (Molnar et al. 2004).13 Increasing trends of policy decentralization could double forest conservation through ICCAs in the near future (White et al. 2004).14 Mobile pastoralism in the drylands is highly influenced by the presence of trees, which provide feed, shade, fuel, and a variety of products that can support livelihoods. In many pastoral communities, trees owned by families are governed by a set of rules and regulations developed and implemented by local institutions. Many dryland farmers also conserve forest cover through agroforestry practices, which, among other benefits, is known to boost fertility and moisture and to provide secondary incomes. Agroforestry is a common land use strategy in the drylands of Africa and Asia, increasingly being recognized as a contributor to biodiversity conservation.

The current global emphasis on maintaining, reviving, and creating forests has major implications for the drylands. There are increasing incentive opportunities for dry forests through carbon credits, although there are barriers to participation in this market and certain associated risks. Weak tenure and poor penetration of government institutions can constrain the use of carbon finance for sustainable land management practices. There is also a risk that incentives to increase forest cover may lead to degradation of important dryland ecosystems—such as savannahs— in pursuit of carbon credits. Carbon stores in dryland ecosystems are predominantly belowground in the root systems, rather than aboveground in standing biomass. Recognition of this and orientation of markets toward compensating for these significant carbon stores will provide important incentives for sustainable land management in the drylands. The spatial scale of the drylands makes them a high priority for climate change mitigation—about 2 × 109 hectares of global shrubland and C4 grassland (Grunzweig et al. 2003).15 Investment in anti-desertification measures in the world’s drylands appears to be an economical method to mitigate carbon dioxide build-up in the atmosphere while accomplishing other international objectives such as combating desertification and conserving dryland biodiversity (Glenn et al. 1993).16

• The definition of drylands and deserts varies between different organizations and government bodies.

• Dryland forests don’t fit the typical definition of forests.

• The preservation of abundant biodiversity and traditional cultures in dryland areas are inextricably linked to the availability and use of indigenous dryland trees.

• Drylands and desert ecosystems can become degraded by planting trees without carefully considering the prevailing ecosystem.