Analysis fingers causes of desertification

A meta-analysis published in the September 2004 issue of BioScience concludes that desertification is driven by a limited group of core variables, most prominently climatic factors that lead to reduced rainfall, technological factors, institutional and policy factors, and economic factors. The technological factors include innovations such as the adoption of water pumps, boreholes, and dams. The institutional and policy factors include agricultural growth policies such as land distribution and redistribution. These variables, the analysis reveals, drive proximate causes of desertification such as the expansion of cropland and overgrazing, the extension of infrastructure, increased aridity, and wood extraction.

Desertification, sometimes referred to as dryland degradation, directly affects over 250 million people and threatens another billion in at-risk countries, many of them among the world's poorest. The new meta-analysis, conducted by Helmut J. Geist and Eric F. Lambin of the University of Louvain in Belgium and the Land Use and Cover Change International Project, considered 132 case studies of dryland degradation. The results challenge single-factor explanations that put the most of the blame for desertification on the rural poor and nomadic populations. Nor do the results support the notion that desertification is the result of irreducibly complex processes. Rather, the analysis suggests that desertification is best explained by a limited number of recurrent pathways that include regionally distinct combinations of factors and feedbacks. Public and individual decisions leading to desertification largely respond to national-scale policies aimed at promoting advanced land-use technologies and creating new economic opportunities.

Journalists may obtain copies of the article by contacting Donna Royston, AIBS communications representative. BioScience publishes commentary and peer-reviewed articles covering a wide range of biological fields, including ecology. The journal has been published since1964. AIBS is an umbrella organization for professional scientific societies and organizations that are involved with biology. It represents over 80 member societies and organizations with a combined membership of over 200,000.

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