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A common language for desertification

Photo credit: Yale Environment Review

 

Finding a common language for the study of desertification

By COLIN BROWN

Desertification is one of the most pressing issues facing the world’s drylands. However, the term “desertification” is only vaguely defined, leading to complications in monitoring and management at all scales.

Arid and semi-arid areas — defined as regions experiencing evapotranspiration in excess of rainfall — may be especially prone to both climatic and human-caused disturbance, due to factors of water scarcity and low soil fertility. These disturbances usually lead to a loss in the ecosystem’s ability to support life, following a breakdown in soil fertility and reduced water availability — a process known as “desertification.”

Desertification is a worldwide problem, but estimating the extent of the phenomenon has been complicated by a lack of consensus in defining the point at which a system has undergone the process. While the UN Convention to Combat Desertification provides one definition, it only does so broadly. The definition does not differentiate between systems that can be restored from those that are permanently lost, or those systems currently in decline from those in recovery. As a result, estimates of desertification can differ widely depending on the researcher or organization, complicating the synthesis of different studies. For instance, in Mongolia, desertification estimates vary between 9 and 90 percent of the country’s land area. Global estimates are not much better, as studies variously estimate the extent of global desertification between 4 and 75 percent.

Researchers from New Mexico State University, UCLA, UC Berkeley, and the U.S. Geological Survey developed a conceptual model to handle the complicated issue of defining desertification. Critically, the model recommends that these ecosystems be categorized as one of three types: equilibrium systems, which are resistant to change and the most likely to stay healthy; tipping point systems, which are prone to sudden and irreversible collapse when pushed past a critical threshold; and non-equilibrium systems, which are unstable, but not prone to rapid deterioration as are tipping point systems.

Read the full article: Yale Environment Review

Published by

Willem Van Cotthem

Honorary Professor of Botany, University of Ghent (Belgium). Scientific Consultant for Desertification and Sustainable Development.