Land degradation and dessertification

Forests in drylands play a very important role. According to the Millennium Ecosystem Assessment (2005), drylands occupy 41% of the earth’s land area and are home to more than two billion people. They protect the land from desertification and conserve biodiversity. They also provide ecosystem goods and services. However, despite their value, forest ecosystems are threatened by deforestation and land degradation. This is especially true in dry forests — forests in arid, semi-arid, and dry sub-humid areas — where the mean annual precipitation is lower than the potential evapotranspiration. There are two major reasons for this: 1) dry forests are more vulnerable to degradation due to low rainfall which increases soil-erosion and reduces water storage capacity in the root zone; and 2) overexploitation of trees, land and soil resources which contributes further to deforestation.
The degradation of forest ecosystems in drylands results in a loss of biomass and biodiversity, water resources, and carbon storage capacity. However, this can be avoided. The protection, restoration and sustainable management of forest resources can both prevent land degradation/desertification and help mitigate and adapt to climate change and the impacts of drought.

Link: http://www.unccd.int/Lists/SiteDocumentLibrary/Publications/Factsheet%207%20redd.ENGweb.pdf