京津冀地区生态系统服务时空变化及驱动因素

京津冀地区地处蒙古高原向华北平原过渡地带,是华北平原关键的生态屏障,在区域生态安全格局上具有重要的地位。结合地面观测、遥感监测、模型模拟和GIS空间分析技术,构建了一套京津冀地区生态系统关键服务的生态本底图谱,分析和评估了京津冀地区生态系统结构与防风固沙、水源涵养、土壤保持等关键服务的时空变化特征,并对气候变化和生态工程等驱动因素进行了讨论。结果表明:(1)京津冀地区生态系统类型以农田为主,占全区面积的49.7%。2000—2015年,聚落面积明显增加,农田面积大量减少,森林、草地、水体与湿地面积微弱减小。(2)多年平均生态系统防风固沙量、水源涵养量和土壤保持量分别为5.61×10~8 t、74.58×10~8 m~3、7.98×10~8 t,燕山-太行山森林生态区的生态系统关键服务量最高,西北草原生态区其次,京津唐和华北农业生态区较低。(3)2000—2015年,防风固沙量、水源涵养量均呈不显著上升趋势,增幅分别0.11 t hm~(-2) a~(-1)、0.03×10~4 m~3 km~(-2) a~(-1);土壤保持量呈显著上升趋势,增幅为1.08 t hm~(-2) a~(-1)。森林生态区各生态系统服务量均呈上升趋势(部分地区P0.05);草原生态区的防风固沙量呈不显著下降趋势,其他服务量整体变化幅度较小;京津唐农业生态区和华北农业生态区东部的防风固沙量呈极显著下降趋势,土壤保持量整呈不显著上升趋势。(4)研究区生长季气候趋于暖湿,叠加实施了多项重点生态修复工程,显著提高了区域植被覆盖度,进而提升了生态系统服务量。而在城市化发展过程中,建设用地不断扩张,导致部分农业生态区植被覆盖度下降,生态系统服务量有所降低。

Spatial and temporal variations in ecosystem services and its driving factors analysis in Jing-Jin-Ji region

The Jing-Jin-Ji region is located in the transition zone of Mongolian plateau and North China Plain, which is an important shelter for the ecological security of North China Plain. Based on field observation, remote sensing monitoring, the quantitative simulation and GIS spatial analysis, we constructed a set of ecological background maps of ecosystem structures and services in Jing-Jin-Ji region. We analyzed the spatial and temporal dynamics of ecosystem structures, sand fixation service, water regulation service, and soil retention service from 2000 to 2015. The impacts of climate change and ecological restoration projects on ecosystem service changes were discussed. The results showed that (1) farmland was the main ecosystem type in the Jing-Jin-Ji region. Urban areas increased significantly, while farmland areas decreased significantly. Forest, grassland and wetland area decreased slightly. (2) In 2000-2015, the average annual volumes of sand fixation, water regulation and soil retention were 5.61×10⁸ t, 74.58×10⁸ m³ and 7.98×10⁸ t, respectively. The ecosystem services in forest ecoregion were the highest among the four ecological-functional zones, and the ecosystem services in agricultural ecoregion were the lowest. (3) From 2000 to 2015, no significant increasing trends were revealed for the sand fixation service and water regulation service with increasing rates of 0.11 t hm^-2 a^-1 and 0.03×10⁴ m³ km^-2 a^-1, respectively. The soil retention service had a significant upward trend with 1.08 t hm^-2 a^-1. There were great differences of ecosystem service changes among four ecological-functional zones. All ecosystem services in forest ecoregion showed the increasing trends (P < 0.05 in some areas), while the sand fixation service in grassland ecoregion was no significant decrease. Unobvious trends of ecosystem key services were presented in other regions. The sand fixation service showed a significantly downward trend, and the soil retention service showed no significantly upward trend in urban and agricultural ecoregion. (4) Overall, the warming and wetting climate during the growing season, and the implementation of a series of key ecological restoration projects contributed to the increasing vegetation coverage and the improvement of the ecosystem services. However, rapid urbanization led to continuous expansion of buildup areas, which resulted in the degradation of vegetation coverage and ecosystem services.