Drylands are characterised by low and erratic rainfall; examples are the African Sahel, Australian Outback and South American Patagonia. They occupy 41 per cent of the earth's land area and are home to 2 billion people. However, desertification and land degradation are reducing their capacity to sustain ecosystems and human livelihoods.
The research outlined the importance of drylands. Some two thirds of the global dryland area is used for livestock production, a source of livelihood for many pastoral communities. It has been estimated that soil carbon sequestration in dryland ecosystems could achieve about 1 billion tonnes of carbon per year. Not only is this one of the world's largest terrestrial carbon sinks, but increasing levels of carbon in the soil increases its capacity to retain water and sustain biodiversity.
Some 12-18 billion tonnes of carbon have already been lost due to desertification, and this figure could increase with climate change. Climate change has also affected the biodiversity of drylands, partly through temperature and precipitation change but also through overgrazing of plants, and land use change.
The restoration and good management of drylands could contribute to both adaptation and mitigation for climate change, as well as increasing food security, protecting biodiversity and reducing risk of drought and flooding. Good management practices include restoring organic matter to soils, reducing erosion and decreasing losses from burning.
Livestock also play a role and there are several 'good grazing' techniques, such as using grazing to stimulate grasses, providing adequate recovery time following grazing and adapting grazing patterns to the impacts of climate change on the plant community. The IPCC estimates that restoration of grasslands and good grazing land management can globally store between 100 and 800 Megatonnes of CO2 equivalents per year. If managed correctly these techniques could lead to healthier grasslands, which in turn could increase livestock productivity.
The study identified a number of barriers to good dryland management, such as unclear land tenure due to the 'common property status' of most drylands and competition from crops, including those used for biofuels. Policies which focus on reducing livestock rather than grazing management are another obstacle. Good management would also be helped by policies which acknowledge the carbon sequestration value of drylands. Existing international carbon trading mechanisms, such as the Clean Development Mechanism do not currently address grazing lands or soil carbon accumulation.
The research indicated that well-managed pastoralism could simultaneously secure livelihoods, conserve ecosystem services, improve carbon sequestration and honour cultural values and traditions. It called for greater support for sustainable pastoral systems. This could include providing incentives to support sustainable and adapted management of drylands, establishing policies that address barriers, such as land tenure, conducting targeted research, such as measuring the amount of carbon sequestration and promoting approaches that integrate the local, national and global aims. It was suggested that some of this could be achieved through Reducing Emissions from Deforestation and Forest Degradation Plus (REDD+).
Source: Neely, C., Bunning, S. & Wilkes, A. (eds). (2009). Review of evidence on drylands pastoral systems and climate change. Implications and opportunities for mitigation and adaptation. Food and Agriculture Organisation of the United Nations. Rome. Downloadable from ftp://ftp.fao.org/docrep/fao/012/i1135e/i1135e00.pdf