基于土地利用的博斯腾湖流域生态系统服务价值时空变化

Spatio⁃temporal change of ecosystem service value in Bosten Lake Watershed based on land use

探讨土地利用变化及其对生态服务功能价值影响,是促进流域生态环境保护和资源合理配置的重要理论依据和决策支持。采用改进的生态系统服务价值评估、热点分析等方法探究了博斯腾湖流域1995—2018年土地利用变化与生态系统服务价值时空(ESV)演变。结果表明:(1)流域旱地、建设用地面积持续增加;荒漠、草甸、湿地、水域、灌木面积呈现波动增长趋势;裸地、草原、冰川积雪、阔叶、针叶面积呈现波动下降趋势。(2)流域23年间ESV呈减小—增大—减小—增大的波动增大趋势,调节服务和支持服务构成流域ESV主体。水域、草甸和草原是流域ESV变化主要的贡献因子和敏感因子,其中水域和草甸为正向贡献因子;草原为负向贡献因子。(3)流域ESV总体空间分布呈"北偏高,南偏低",唯一高值集聚区(博斯腾湖)点缀在低值区的格局,ESV南北空间差异明显;研究区年平均湿地和水域面积之和仅占总面积的3.61%,主导着整个流域生态系统服务价值的变化,是流域环境保护和生态建设的重心。(4)流域生态系统服务价值热点区域变化不大,冷点区域面积大且呈缩减趋势。流域北部的ESV空间演变较为显著,其原因是荒漠和裸地、草原和草甸等自然生态系统转换频繁。研究区南部的绿洲区的扩张使得局部冷点区转为次冷点区。

Assessments of the effect of land⁃use change and the ecosystem service value(ESV)provide critically important information that has implications for ecological protection and the rational allocation of resources in terrestrial ecosystems,especially for fragile and threatened ecosystems in arid lands.Here,we used the modified ESV evaluation and hotspot analysis methods to analyze land use cover change and ESV from 1995 to 2018 in the Bosten Lake watershed.We found that(1)the area of dry land and construction land increased continuously;the area of desert,meadow,wetland,water area,and shrubland exhibited a fluctuating increasing pattern;and the area of bare land,grassland,glacier snow,broadleaf forest,and coniferous forest showed a fluctuating decreasing pattern.(2)The ESV first decreased,then increased,decreased again,and then increased.The ESV indicates that regulation and supporting services were the main services provided.Water area,meadow,and grassland were the main factors contributing to ESV change:water area and meadow contributed positively,whereas grassland contributed negatively.(3)ESV was higher in the northwest than in the southeast.The only high⁃value agglomeration area(Bosten Lake)was distributed in the area of low ESV.The ESV significantly varied along the north-south gradient in the watershed.The annual average area of wetland and water area,which occupied 3.61%of the entire study area,is the focus of environmental protection and ecological construction in the Bosten Lake watershed.(4)The ESV hotspot area varied little during the study period,and the ESV cold spot area was larger than the hotspot area and decreased throughout the study period.Conversions between desert,grassland,meadow,and bare land systems were frequent,which led to significant variation in the ESV in the northern part of the study area.The increase in the size of the oasis resulted in a change in the cold spot area in the southern part of the study area.