坝上高原生态用地时空格局演变与生态系统服务价值分析

Analysis of ecological land pattern evolution and ecosystem service value in Bashang plateau

为了给当地的生态用地保护和区域间生态补偿提供科学依据,该研究在坝上高原地区1990、1995、2000、2005、2010和2015年6期土地利用解译数据的基础上,通过GIS等工具分析了研究区域1990-2015年间生态用地格局演变的基本特征,并对生态用地的生态系统服务价值进行了计算。主要结论如下:1990-2015年期间,研究区域生态用地数量呈减少趋势,其中林地和其他生态用地数量在增加,草地和湿地数量在减少。生态用地活跃程度在2000-2015年比1990-2000年期间更高。林地的空间稳定性最好,然后为草地和湿地,其他生态用地稳定性最差。生态用地生态系统服务价值由46.01亿元上升到428.26亿元,增加了8.31倍,林地和湿地提供的生态系统服务价值最大,其次为草地,其他生态用地最小,应当继续加强生态防护林建设,采取生物恢复技术,人工补水,科学禁牧、休牧、轮牧,调整产业结构等措施恢复和增加林地、湿地和草地的生态系统服务功能。

Ecological land is of great significance in safeguarding important ecological processes and providing essential ecosystem services, and the classification and evaluation of the ecosystem services of ecological land have become increasingly important in recent years. In order to change the trend of ecological land loss caused by blind economic development and to improve the regional pattern for ecological security, it is necessary to study the rational allocation of the quantitative structure and the spatial patterns of ecological land. Based on land use data of Bashang plateau in 1990, 1995, 2000, 2005, 2010 and 2015, GIS（geographic information system） technology was used to analyze ecological land pattern evolution and ecosystem service values of Bashang plateau. The results were as follows：（1） The ecological land in Bashang plateau was classified into 4 types（forest, grassland, wetland and other ecological land） and 15 sub-types; the quantity of ecological land decreased from 904 500 to 881 800 hm^2 during 1990- 2015 due to the decreased grassland and wetland and the increased forest and other ecological land. The quantities of forest and other ecological land increased from 275 000 and 8 300 to 324 900 and 11 300 hm^2 respectively, and meanwhile the quantities of grassland and wetland decreased from 501 500 and 119 700 to 437 300 and 108 300 hm^2 respectively.（2） The transfer rates of forest, other ecological land, grassland and wetland were 1.45%, 0.73%,-0.51% and-0.38% from 1990 to 2015, respectively. The dynamic degree during 1990-2000 was-0.50%, while it was 2.43% during 2000-2015, which indicated that the activity degree of ecological land in 2000-2015 was much higher than that in 1990-2000. The decrease of grassland and the increase of forest land accelerated, while the reduction of wetland slowed down, and other ecological land change increased. All of these were mainly due to a series of key ecological projects that were carried out in Bashang plateau to control sandstorm source of Tianjin and Beijing, which have led to the rapid growth of forest; meanwhile, as the climate of Bashang plateau tended to be dry after entering 21 century, as well as the unreasonable utilization of grassland and wetland resources, the areas of grassland and wetland decreased.（3） The retention land rates of forest, grassland, wetland and other ecosystem land in the study area were 63.22%, 41.23%, 34.88% and 11.90% respectively, indicating that the spatial stability of forest was the best, followed by grassland and wetland, and the stability of other ecological land was the worst. The ecological evolution process was mainly concentrated in the transfer from grassland to non-ecological land and forest, the transfer from forest to grassland, the transfer from wetland to non-ecological land and the transfer from non-ecological land to grassland and forest. The transfer from non-ecological land to grassland and forest land showed that the series of ecological construction projects had achieved initial success.（4） The ecosystem service values of ecological land decreased from 46.01×108 yuan in 1990 to 428.26×108 yuan in 2015, enlarged by 831%. The average annual growth rate of ecosystem service values increased from 15.82% during 1990-2000 to 17.37% during 2000-2015. The forest ecosystem service values were the maximum, while the other ecological land ecosystem service values were the minimum. We should continue to strengthen the construction of ecological nature preserves, use biological recovery technology and artificial replenishment such as scientific grazing, adjust the industrial structure and use other measures to restore and increase the forest, wetland and grassland ecosystems.