基于遥感与GIS的渭库绿洲生态系统服务价值时空变化研究

生态系统服务价值(ESV)研究是改善土地利用方式,对促进地区生态系统保护和修复具有重要指导意义。选择生态环境较为脆弱的渭库绿洲为研究区域,以1994和2016年遥感影像为基础数据进行生态服务价值评估,应用格网、敏感性分析、空间自相关等空间统计学方法来进一步揭示研究区域生态系统服务价值(ESV)动态变化特征。结果表明:(1)1994—2016年间渭库绿洲土地利用变化/土地覆被变化较为显著,耕地,建设用地面积呈增长趋势,水域、草地和未利用地面积呈递减趋势,耕地和草地面积变化最为剧烈。(2)1994—2016年,渭库绿洲的生态系统服务总价值呈减少趋势,由4895.67×10~6元减少到3864.78×10~6元,减少了1030.89×10~6元,年均减少0.96%;空间上表现为生态服务价值增值区及减值区呈包围态势,生态系统服务高值区域在不断缩小;同时生态系统单项服务价值呈现有增有减的趋势,废物处理、水源涵养、生物多样性保护、娱乐文化等四项单项服务价值呈现下降趋势,而食物生产、气候调节、气体调节和原材料、土壤形成与保护等其他五项单项服务价值出现上升趋势。(3)敏感性分析表明,所有土地利用类型生态系统服务价值系数的敏感性指数(CS)均小于1,说明生态价值系数(VC)对生态系统服务价值的变化影响较小,模型能够合理评估该区域生态服务价值波动。(4)研究区生态系统服务价值表现出明显的空间自相关与空间聚集现象,生态服务价值高值聚集区主要分布在渭干河上游"克孜尔水库"周围和塔里木河北岸,并呈减少趋势,注意保护高值区的空间稳定性;低值聚集区主要集中在绿洲南部靠近塔克拉玛干沙漠边缘和北部靠近天山中部的山区以及库车河下游荒漠区域,这类区域在空间范围上呈连片连绵趋势,空间分布格局上基本保持稳定。(5)受气候变化和人类活动的双重影响下,草地和水域面积的大幅度下降,耕地和建设用地面积的增加,导致生态服务价值系数较高的土地越来越少,使得研究区的生态服务价值趋于减弱。

The ecosystem service value spatial-temporal changes in the Ugan-kuqa River Delta Oasis based on RS and GIS

Ecosystem services value (ESV) research is an important way to improve land use patterns and to promote the protection and restoration of regional ecosystems. This study choose the fragile ecological environment of the Ugan-Kuqa River delta oasis as a study area, using remote sensing images in 1994 and 2016 as the basic data to assess the value of ecosystem services. To further investigate dynamic change characteristics of regional ecosystem service values, the grid, sensitivity analysis, spatial autocorrelation, and spatial statistical methods were applied. The results revealed that:(1) 1994-2016 Ugan-Kuqa River delta oasis land use changed, and land cover changed was more significant. Cultivated land and construction land showed an increasing trend, whereas grassland and unused land showed a declining trend. Cultivated land and grassland changed most rapidly. (2) From 1994 to 2016, the total value of ecosystem services in the Ugan-Kuqa River delta oasis decreased from 4895.67×10⁶ yuan to 3864.78×10⁶ yuan, being reduced by 1030.89×10⁶ yuan, an annual reduction of 0.96%; in spaces where the ecological service value added area in the impairment area were in a situation of encirclement. Areas of high ecosystem service value were shrinking. At the same time, the value of ecosystem individual services presented an increasing and decreasing trend. Four single service values, such as waste treatment, water conservation, biodiversity protection, and recreational culture, there was a downward trend. However, food production, climate regulation, gas regulation and raw material, soil formation, and protection, and an additional five individual service values showed an upward trend. (3) The sensitivity analysis revealed that the sensitivity index of ecosystem service value coefficient (CS) of all land use types were less than 1, indicating that the ecological value coefficient (VC) had little influence on the changes of ecosystem service values, the model can reasonably evaluate the fluctuation of regional ecosystem service values. (4) The ecosystem service value of the study area showed obvious spatial autocorrelation and spatial clustering, ecological service value high accumulation areas were mainly distributed in the Ugan-Kuqa River upstream, in the "Kezier reservoir" around and north shore of the Tarim River and showed a decreasing trend. Protection of the spatial stability of the high value area must be considered; the low accumulation area mainly concentrated in the southern part of the oasis was close to the edge of the Taklimakan Desert and near the Tianshan Mountain central area and desert area of the lower reaches of the Kuqa River. The spatial distribution pattern of this kind of area is basically stable. (5) Affected by climate change and human activities, the grassland and water area was greatly reduced and construction land and cultivated land was increased, resulting in the land with higher ecological service value coefficient being continuously reduced, which causes the ecological service value of the study area tend to weaken.