Assessment of recent rapid land-cover change yields portraits of global human impact

Study is based on data compiled from remote sensing, censuses, and expert opinion

The February 2005 issue of BioScience, the monthly journal of the American Institute of Biological Sciences (AIBS), includes a new assessment of rapid land-cover change around the world over the period from 1981 to 2000. Changes in the use to which land is put have important implications for climate change and loss of biodiversity, and affect local populations’ access to food and clean drinking water. The study, conducted under the auspices of the Millennium Ecosystem Assessment by Erika Lepers of the University of Louvain in Belgium and six co-authors, examined forest-cover changes, degraded lands in dry regions (often referred to as desertification), cropland expansion and abandonment, and urban settlements. The assessment is based on data compiled from remote sensing and censuses as well as expert opinion.

The results indicate that whereas Asia has the greatest concentration of areas of rapid land-cover change, in particular dryland degradation, existing data do not support the claim that the African Sahel is a desertification hotspot. The Amazon Basin remains a hotspot of tropical deforestation, the assessment concludes, and rapid cropland increase is prominent in Southeast Asia. But forest degradation is also increasing rapidly in Siberia, mostly as a result of logging, and the southeastern United States and eastern China are experiencing rapid cropland decrease.

Lepers and her colleagues note that information is not complete globally, and the synthesis was complicated by varying definitions used in different data sets. An extensive process of consultation nevertheless allowed a useful picture to emerge; the assessment includes global maps showing regions of rapid land-cover change. The most populated areas of the world, the study notes, are located in the Gangetic Plain of northern India, the plain and north plateau of China, and the island of Java in Indonesia. Cities that are changing most rapidly are located throughout the tropical belt.