喀斯特生态系统服务价值时空分异及其与环境因子的关系

揭示西南喀斯特生态系统服务价值时空变化特征及其与环境因子的关系是喀斯特地区生态恢复与重建中亟待解决的问题。本研究基于多时相遥感影像、气象观测数据和统计资料,对桂西北典型喀斯特地区1985～2005年的生态系统服务价值进行定量评估与分析,并利用典范对应分析方法对其与环境因子的关系进行探讨。结果表明:1985年-2000年-2005年期间生态系统服务价值呈先降后升的"V"字形变化趋势,3个年份分别是1096.52亿元、1033.84亿元和1062.57亿元;营养物循环、调节气体、有机质生产和土壤形成价值较高,其总贡献率分别为72.69%、70.18%和72.10%;而涵养水源、土壤保持和娱乐文化相对较低,都远低于100亿元。林地和灌木是生态系统服务价值的主要贡献景观类型,两者的总贡献率在3个年份分别是71.22%、73.66%和67.03%;居民用地和石漠化地的生态系统服务价值非常低,3个年份贡献率分别仅有0.62%、0.52%和0.76%。CCA排序图显示生态系统服务价值与环境因子存在紧密关系,坡度、海拔等环境因子对生态系统服务价值的影响较大,且其影响存在显著的空间分异特征。研究区域生态系统服务价值呈由西向东减少的空间分异特征;1985～2005年期间,典型喀斯特地区生态系统服务价值显著增加,而非喀斯特地区生态系统服务价值明显减少。表明生态环境移民和退耕还林等石漠化控制措施实施效果显著,有利于生态系统服务的发挥。

Spatio-temporal variation of karst ecosystem service value and its correlation with ambient environmental factor

For the restoration and reconstruction of karst ecosystems, it is vital to explore the spatio-temporal variations in ecosystem service value of karst regions in Southwest China and its correlation with ambient environmental factors. Based on multi-temporal satellite imagery, weather and statistical data, spatial distributions and dynamics of karst ecosystem service value were evaluated for Northwest Guangxi. The links between karst ecosystem service value and ambient environmental conditions were also analyzed for 1985~2005 using Canonical Correspondence Analysis (CCA). The results show an initial decline in karst ecosystem service value, followed by a steady increase at 109.652, 103.384 and 106.257 billion Yuan in 1985, 2000 and 2005 respectively. Ecosystem service values for nutrient cycling, organic matter production, gas regulation and soil formation are high, with respective total contribution ratio of 72.69%, 70.18% and 72.10% in 1985, 2000 and 2005. However, ecosystem service values for water and soil conservation, recreation and culture are much low and well below 10 billion Yuan. Woodlands and shrubs are the main contributors to ecosystem service value with total contribution ratio of 71.22%, 73.66% and 67.03% in 1985, 2000 and 2005 respectively. While residential and rocky land contribute less to the ecosystem service, their contribution ratio sum are 0.62%, 0.52% and 0.76%, respectively. CCA ordination diagram shows that ecosystem service values are closely linked with ambient environmental factors. Slope gradient, elevation have a significant impact on ecosystem service value. There also exist significant spatio-temporal differences among these factors. Ecosystem service value of the studied area shows a declining trend from West to East. Ecosystem service value for typical karst regions is obviously increasing, while that for non-karst regions markedly decreasing. Based on the study, ecological conditions are improving due to better policies such as ecological migration and afforestation of farmlands to control rock desertification.