Abandonment of agricultural land: an overview of drivers and consequences.

Agricultural activities and their complex effects on nature conservation, and the services that ecosystems deliver to humans are controversial. We present an overview of land abandonment, its driving forces and its consequences for landscape, biodiversity and humans. A descriptive metaanalysis of independently published studies highlighted the fact that the abandonment of agricultural land is a phenomenon mostly driven by socio-economic factors such as immigration into areas where new economic opportunities are offered to rural people. Ecological drivers such as elevation and land mismanagement leading to soil erosion are of secondary importance. We identified the major problems related to abandonment of agricultural land and quantified their relative importance. In order of decreasing importance, they were biodiversity loss, increase of fire frequency and intensity, soil erosion and desertification, loss of cultural and/or aesthetic values, reduction of landscape diversity and reduction of water provision. The impacts of these problems were not equally relevant in all regions of the world. The abandonment of agricultural land may also benefit humans. The benefits include passive revegetation and active reforestation, water regulation, soil recovery, nutrient cycling and increased biodiversity and wilderness. In a world that is becoming less natural and more intensively exploited by humans, we suggest that (1) farmland must be viewed in a context of multi-functionality to take advantage of ecosystem goods and services, (2) at the global scale, the abandonment of agricultural land is mostly positive for humans and (3) there is a need for the implementation of policies based on the payments for environmental services that encourage human societies to reconcile agricultural use, nature conservation and ecological restoration.