Effects of land-use conversions on the ecosystem services in the agro-pastoral ecotone of northern China

摘要

As the material base and natural resources of human society, ecosystem services play an essential role in the sustainable development of the ecosystem. Land-use conversions can remarkably alter the provision of ecosystem services. Owing to natural factors and human interventions, the land-use structure has undergone complex changes over the past few decades in the agro-pastoral ecotone of Northern China. Hence, objectively evaluating the losses of ecosystem service values (ESVs) in the agro-pastoral ecotone of Northern China and accordingly implementing decision-making and policy evaluation for sustainable development is remarkably important. However, in terms of ecosystem services, only few holistic studies have considered the agricultural zone and pastoral area as controls to assess the spatiotemporal variation in the agro-pastoral ecotone. In this study, we quantitatively evaluated the losses of ESVs in the agro-pastoral ecotone compared to those in the agricultural zone and pastoral area on a macro-scale between 1980 and 2015. The results were as follows: (1) the main characteristic of land conversions was that large areas of grassland were converted into cultivated lands in the agro-pastoral ecotone, and its density of land conversions was remarkably higher than that in the agricultural zone and pastoral area; (2) on the spatial scale, the agro-pastoral ecotone lost more ESVs than the agricultural zone and pastoral area (P < 0.05); in contrast, on the temporal scale, the losses were noted in the following order: 1990-2000 > 1980-1990 > 2000-2015; and (3) the agro-pastoral ecotone lost more ESVs, mainly owing to three land conversions, which were grassland transformation into cultivated land, cultivated land transformation into unused lands, and grassland transformation into built-up areas. Although these land conversions were curbed after the implementation of protection policies at the end of the 1990s, they had a tendency to expand to the pastoral area. Therefore, we think that human interference is the main cause of ecological deterioration in the agro-pastoral ecotone. This study provides measures for restricting human activities and a perspective for the application of ESVs in sustainable development. (C) 2019 Elsevier Ltd. All rights reserved.