洋河流域土地利用时空变异及其对生态服务功能价值的影响

洋河流域位于我国北方典型的农牧交错地带,是首都重要水源涵养地和生态保护屏障,也是2022年冬奥会举办地之一。对流域土地利用变化及其生态服务功能价值影响的研究可为首都水源保护以及冬奥会场地环境质量的改善提供重要理论依据和决策支持。利用Arc GIS技术分析了洋河流域1990—2013年间的土地遥感数据,估算了这些变化对流域生态服务价值的影响。结果表明:1990—2013年洋河流域林地和未利用地面积呈增加,而水域、草地则呈减少的趋势。由单一土地类型利用动态绝对值说明,除林地以外2000—2013年洋河流域其他土地类型受人类或自然环境变化的影响明显高于1990—2000年。土地转移主要发生在流域西部的兴和县、阳高县、天镇县和下游的张家口市、宣化县和怀来县。近年来流域土地面积变化幅度和变化范围均增加。1990—2013年间洋河流域土地利用的年总生态服务价值经历先增加后减小、总体减少的过程,但林地和未利用地的生态服务价值却一直增加。由于林地面积增加从而导致1990—2013年流域的原材料生产、气候调节、气体调节、生物多样性保护和提供美学景生态功能占年总价值的比值增加。林地、草地和耕地是洋河流域生态服务的主要贡献者,也是生态服务价值变化的敏感因子。

Temporal and spatial variation of land use and their influence on ecosystem service function values in the Yanghe Watershed, China

The Yanghe Watershed is located in a typical farming pastoral zone of North China. It is an important water-source conservation site and an ecological protection barrier for Beijing. Furthermore, the 2022 Winter Olympic Games will be held in Zhangjiakou City, which is a key region of the Yanghe Watershed. A study of land use changes and their ecosystem service-function values of the watershed can provide important theories for effective decision-making regarding water resource protection and environmental quality improvement in fields of the areas where the games will be held. ArcGIS was used to analyze remote sensing data of land-use changes that occurred within the Yanghe Watershed from 1990 to 2013, and ecosystem service-function values of the lands were estimated. The results showed that forest and unused lands within the watershed increased, whereas grassland and aquatic areas decreased during the study period. Based on absolute values of the changing rate of a single land-use type, apart from forestland, the other land-use types were more greatly affected by human or natural changes in 2000-2013 than in 1990-2000. Land transfers mainly occurred in Xihe, Yanggao, Tianzhen, Xuanhua, and Huailia Counties, and the land change degree and distribution increased in recent years. The annual value of total ecosystem service functions of the lands increased during 1990-2000 and decreased during 2000-2013; however, overall it decreased from 1990 to 2013. Service function values of grassland, aquatic areas, and farmland decreased, whereas that of forest and unused land increased during 1990-2013. Percentages of values of raw material production, climate regulation, air conditioning, biodiversity conservation, and esthetic landscape increased owing to increases of forestland within the watershed during the study period. Forest-, grass-, and farmlands were not only the main contributors but also sensitive factors to ecosystem service function values of the lands within the Yanghe Watershed from 1990 to 2013.