生态公益林补偿政策对植被覆盖时空格局的影响——以杭州市临安区为例

Effects of forest compensation policy for public welfare on the spatiotemporal patterns and dynamics of vegetation cover: a case study at Lin'an,Hangzhou City

生态补偿政策绩效评价对完善政策调控和促进植被恢复具有重要意义。分析了临安2001—2015年植被覆盖的时空格局和变化,建立了植被退化地区土地利用变化矩阵。在Arc GIS软件中建立了临安地区归一化植被指数(NDVI)、国家级和省级公益林覆盖边界(重点生态公益林补偿边界)、道路、海拔、中心城镇用地边界、重点森林保护区、河流边界和地形湿度指数的多要素地理空间数据集。采用多元回归模型量化了重点生态公益林补偿政策、自然因素、城市化和其他人类活动对植被覆盖变化的影响。结果表明,2001—2015年间,临安大约有97%的林地呈现出不同程度的退化,其中中等退化程度的林地所占比例最高。多元线性回归模型的结果表明重点生态公益林补偿政策、海拔、河流距离、重点森林保护区距离和中心城镇距离对植被退化有抑制作用,道路和地形湿度指数对植被退化有促进作用。海拔在所有的外部影响因素中对植被退化的影响最大。政策覆盖地区的植被退化面积在每一个退化等级上都小于无政策覆盖地区。生态公益林补偿政策的实施对加强植被的保护,限制不合理的林地利用和改善区域环境质量具有十分重要的积极作用。

Evaluation of the effect of ecological compensation policies is important for improving policy regulations and vegetation recovery. We analyzed the spatiotemporal pattern of vegetation cover from 2001 to 2015 at Lin＇an City. We established the land-use change matrix in vegetation degraded area. We created a geodatabase in ArcGIS, including the Normalized Differential Vegetation Index （NDVI）, national and provincial boundary of forest compensation policy for public welfare, built-up area, road, elevation, key forest reserves, rivers, and topographic wetness index. Finally, we used the multiple linear regression analysis to estimate the effects of national and provincial forest compensation policy for public welfare, biophysical factors, urbanization, and other human activities on vegetation cover change. Our results show that, during the 2001 to 2015, approximately 97% of the vegetated areas have suffered different levels of decline or degradation, with the moderate level of degradation constituting the largest proportion. The results of multiple linear regressions suggest that policy, elevation, distance to river, distance to key forest reserves, and distance to the center of the town have a significantly negative correlation with vegetation degradation, whereas distance to road and topographic wetness index have a positive correlation with vegetation degradation. Elevation has the greatest effect among the external factors analyzed. Moreover, in each degradation level, the areas where the compensation policy was implemented suffered a lower degradation than the other areas did. Our findings suggest that the implementation of ecological compensation policy plays a positive role in protecting vegetation cover, restricting inappropriate utilization, and improving regional environment quality.