Desertification and land degradation

A controversial debate surrounds the definition of desertification, what causes desertification and how it is manifested, where it occurs, and how it links to natural phenomena and to human actions. Literature concerning the nature and occurrence of desertification is voluminous and there is an excess of definitions of desertification.

The United Nations Convention to Combat Desertification (UNCCD) defines desertification as 'land degradation in arid, semi-arid and dry sub-humid areas resulting from various factors, including climatic variations and human activities'.

Importantly, land degradation is referring generally to the reduction or loss of the biological or economic productivity and complexity of land, whereas desertification is specifically referring to the degradation of drylands.

Desertification aggravates poverty
Desertification is considered as one of the major global environmental challenges we face today. As the Millennium Ecosystem Assessment (MA) states, desertification is potentially the most threatening ecosystem change impacting the livelihoods of the poor. The MA estimates (medium certainty) that some 10 – 20% of drylands are already degraded.

The degradation of arid lands jeopardizes human well-being. Reduced vegetation cover, soil erosion and salinization severely decrease the biological productivity of drylands and thus reduces the production of food. Desertification is aggravated by droughts and probably climate change. People living in drylands have to more and more use marginal land or to migrate to other areas. The increased pressure on land with low productivity contributes further to desertification.

In addition to the immediate effects on the local level, desertification also affects the climate and air quality on the regional and global level. Reduced vegetation cover increases the amount of dust in the air. This affects not only the air quality and thus human health but impacts further the regional and global climate. Soil erosion leads further to the silting of rivers and water reservoirs.

Causes of desertification
Reduced dryland vegetation – caused by for instance overgrazing and deforestation – leads to the erosion and oxidation of fertile soil. Similarly, salinity triggered by excessive irrigation practice decreases soil fertility and lowers consequently the productivity of drylands. The inappropriate use of drylands, such as overgrazing, deforestation or inappropriate irrigation is mostly driven by demographic, economic and social-political factors. Climate change might further affect the chemical, physical and biological processes and thus contribute to desertification.

How to halt desertification
Several international, regional and national environmental agreements have been put in place to provide frameworks, guidelines and assistance to policy makers, scientist and people in the field. However, much has to be done to improve the political commitment and to overcome the lack of financial resources to provide better guidance and support for sound management plans and practices for the benefit of the people living in drylands.

It is necessary to address political, social and economic constraints, globally and in the regions, to path the way for the sustainable management of drylands. This will include providing alternative livelihood opportunities, tenure security, appropriate and improved grazing and irrigation practices and even more important the support for the traditional sustainable management of drylands.

The Ecosystem Approach as a strategy for the integrated management of land, water and living resources is thus of particular significance to drylands.