Soil erosion as a driver of land-use change

Abstract

Although much research has been carried out on the crop productivity response to soil erosion, little is known about the role of soil erosion as a driver of land-use change. Given, however, the some-times large erosion-induced reductions in crop yields, it appears likely that erosion has a strong impact on land-use. Abandonment of arable land due to declining productivity is a land-use change that may result from soil erosion. To test this hypothesis, the western part of Lesvos, Greece, was chosen as a case study area. Lesvos has experienced accelerated erosion on marginal soils over the last century during which important land-use changes have taken place. Of the 3211 ha that were under cereals in 1886, 53% (1711 ha) was converted to rangeland (only used for extensive grazing) by the mid-20th century. At the same time, however, cereals partly returned to neighbouring areas that were previously rangeland, implying that certain processes at the local scale resulted in land becoming unsuitable in one place and (relatively) more suitable in other places. In order to identify the relationship between these land-use changes and the occurrence of soil erosion, erosion was modelled backwards for the period 1886–1996 and soil depths reconstructed for the time when the land-use was assumed to have changed (the mid-1950s). A logistic regression was performed with soil depth, erosion and slope as explanatory variables and land-use change as the response variable. Abandonment/reallocation of cereals was found to be fairly well predicted by slope and soil depth. Path analysis showed erosion to be an important driver for the abandonment and reallocation of cereals, although next to slope and soil depth it has little additional predictive value. Based on the logistic model, it is anticipated that cereal cultivation in western Lesvos will probably be abandoned in the near future.