京津风沙源治理工程区土地利用/覆盖变化及生态系统服务价值响应

Land use/cover change and its ecosystem service value response in the Beijing-Tianjin sandstorm source control project area

监测土地利用/覆盖及生态系统服务价值变化是评估生态工程效益最直接有效的方式。以京津风沙源治理工程区为研究区,基于土地利用/覆盖变化面积和植被覆盖度等指标,从土地利用/覆盖类型转换和土地覆盖渐变两个角度揭示区域土地利用/覆盖变化过程;并运用改进的当量因子法,评估同期生态系统服务价值的变化。结果表明:区域草地面积超过总面积的一半,总体上呈现草地和耕地集中分布,林地、沙丘零散镶嵌的格局。1990—2018年,区域沙地、草地面积减少,耕地、林地面积增加;同时,沙地上表现出植被覆盖增加的渐变特征,增速为每10年约增长4.22%。同期区域生态系统服务价值呈现出先减少后增加的趋势,生态工程实施后,2010—2018年生态系统服务价值增加明显。1990—2018年,生态系统服务价值总体上增加了3655.21亿元,其中,由土地利用/覆盖类型变化导致的价值增加量为120.53亿元,而由土地覆盖渐变导致的增加量为5355.04亿元。土地覆盖渐变对生态系统服务价值的影响不容忽视,我们建议在生态建设过程中,不仅要重视退耕还林、未利用地造林种草等土地利用/覆盖方式的改变,更要关注草地和林地的修复和恢复,注重生态工程成果的维持和质量的提升。

Monitoring land use/cover and changes in ecosystem service value is one of the most direct and effective ways to assess the benefits of ecological engineering.This study took the Beijing-Tianjin sandstorm source control project area as the research area.Based on indicators such as land use/cover change area and vegetation coverage,land use/cover changes were revealed from the perspectives of land use/cover conversion and land cover modification.Then the ecosystem service value(ESV)was evaluated using the improved equivalent factor method.The results showed that grassland covered more than half of the study area.From 1990 to 2018,the sandy lands and grasslands indicated a decline trend with the increasing of croplands and forests.The vegetation on sandy lands showed a significant improving trend with the annual increase rate of 4.22%per decade.During the same period,the ESV showed a trend of first decrease and then increase.Due to the reduction of sandy land and grassland area and the increase of woodland and cropland area after the implementation of ecological projects,the ESV increased significantly during 2010-2018.From 1990 to 2018,the ESV generally increased by 365.521 billion RMB,of which the increase caused by land use/cover conversion was 12.05 billion RMB,and the increase caused by land cover modification was 535.504 billion RMB.This study showed that the impact of land cover modification on the ESV cannot be ignored.We suggested that in the process of ecological construction,we should not only pay attention to the change of land use/cover mode,such as returning farmland to forest,afforestation and grass planting on unused land,but also pay attention to the restoration and restoration of grassland and woodland,and pay attention to the maintenance and quality improvement of ecological engineering achievements.