基于InVEST模型的门头沟区生态系统土壤保持功能研究

人类不合理的土地资源开发所导致的土壤侵蚀成为山区生态系统关注的热点和焦点问题。选择生态涵养与土壤侵蚀并存的北京市纯山区门头沟区为研究区域，在分析2005—2013年门头沟区土地利用与土地覆被变化的时空差异的基础上，采用了InVEST模型对区内生态系统的土壤保持功能进行了定量分析和动态评估。研究表明:（1）2005—2013年，门头沟区耕地、林地和水域、未利用地面积减少，园地、草地、建设用地增加；耕地和园地变化显著，耕地主要转为园地、林地和建设用地；园地主要由耕地和林地转化而来。（2）2005—2013年，门头沟区土壤保持能力和保持量均呈增加趋势，单位面积土壤保持能力由87.41 t/（hm²·a）增加到113.56 t/（hm²·a），土壤保持量增加了377.38万t，土壤侵蚀量减少了23.42万t；受土地利用与土地覆被变化、降雨侵蚀力以及植被覆盖度影响，西北、东北地区土壤保持功能增强，西南地区减弱，东部地区基本不变。（3）不同土地利用与土地覆被类型的土壤保持能力排序为:林地 > 草地 > 未利用地 > 建设用地 > 耕地 > 园地 > 水域；2005—2013年，不同土地利用/覆被类型的单位面积土壤保持能力均呈增加趋势；除耕地外，其他地类的土壤保持总量均呈增加趋势。

Study on Soil Conservation Service of Ecosystem Based on InVEST Model in Mentougou District of Beijing

Soil erosion caused by unreasonable land resources development has become a hotspot in mountain ecosystem. Based on temporal and spatial analysis of land use and land cover changes (LUCC) between 2005 and 2013, soil conservation service of ecosystem based on InVEST model in Mentougou District of Beijing, which was pure mountainous areas with ecological conservation and soil erosion characteristics, was analyzed quantitatively and evaluated dynamically. The results showed that: (1) the acreages of cultivated land, forestland, waterbody and unused land presented the decreasing trend in contrast to garden plot, grassland, construction land from 2005 to 2013; and the cultivated land was the fastest decreasing type, and was mainly converted into garden plot, forestland and construction land, respectively; meanwhile, the garden plot was the fastest growing type, and was mainly derived from cultivated land and forest land; (2) both the soil conservation ability and capacity of Mentougou ecosystem increased during 2005—2013, annual per unit area of soil conservation capacity raised from 87.41 t/hm² to 113.56 t/hm²; total soil conservation increased by 3.773 8 million t, while reduced soil erosion was 0.234 2 million t; the capacity of soil conservation in northwest and northeast showed the upward trend, a decreasing trend in southwest, and unchanged in the eastern region; (3) the soil conservation capacity per unit area decreased in the order: forestland > grassland > unused land > construction land > cultivated land > garden plot > waterbody, between 2005 and 2013, soil conservation capacity per unit area of different land use and land cover types tended to increase; the unused land had the fastest growth rate in soil conservation function, while waterbody presented the slowest growth rate; in addition to cultivated land, the total amount of soil conservation of other types showed the increasing trend.