基于连清数据的广州市1979—2012年森林生态功能的变化

Dynamic analyses of forest ecological functions based on fixed plot data of continuous forest resources inventories from 1979 to 2012 in Guangzhou

【目的】高效的森林经营必须建立在生态合理性的基础上,分析区域尺度的森林生态功能综合评价及驱动因素,可为制定森林经营规划提供科学参考。【方法】以珠江三角洲的广州市为研究对象,以1979—2012年148块8期森林资源连续清查固定样地数据为主要信息源,在构建生态功能指数基础上,进行研究区生态功能时空变化及驱动因素分析。【结果】(1)1979—2012年,研究区森林生态功能指数提高的样地数多于降低的样地数,中高等级样地数的比例呈稳步增加趋势,低等级样地比例呈现阶梯状下降趋势;(2)1979—2012年,研究区森林生态功能的空间聚集性呈现先增大后急剧下降、又缓慢增强的复杂变化历程,生态功能高值点地理分布中心呈现由南向北、由西向东逐渐偏移的趋势;(3)地理加权回归分析显示,影响研究区森林生态功能空间差异性的前4个主要驱动因素大小依次为海拔>植被覆盖度>坡度>人均GDP。【结论】城市化、工业化引发的林地占用与退化,林业政策法规变动对林农森林经营积极性的影响,是导致区域森林生态功能变化的主要驱动因素;加强森林经营与林地保护,是提高区域森林生态服务功能的必由之路。

【Objective】 The scientific forest management should be established based on the ecological rationality. A comprehensive evaluation of forest ecological functions and an analysis of driving factors at the regional scale can provide scientific references for the formulation of forest management plans. 【Method】 Guangzhou City in the Pearl River Delta was selected as the case study area, and 148 fixed plot data of continuous forest resource inventories from 1979 to 2012 in eight periods were collected as the main information source. The spatiotemporal changes and driving factors of forest ecological functions were analyzed based on the construction of the ecological function index. 【Result】(1) From 1979 to 2012, the number of plots with improved forest ecological functions in the study area was greater than the number of plots with the decreased. The proportion of middle and high grade plots showed a steady increasing trend, whereas the proportion of low grade plots showed a stepwise downward trend.(2) From 1979 to 2012, the spatial aggregation of forest ecological functions in the study area showed a complex change process that first increased, then declined sharply, and then slowly increased. The geographical distribution centers of the high-value points of ecological functions gradually shifted from south to north and west to east.(3) The geographically weighted regression(GWR) analysis showed that the first four main driving factors affecting the spatial difference in forest ecological functions in the study area were ranked as follows: altitude>vegetation fractional coverage>slope> per capita gross domestic product(GDP). 【Conclusion】 The occupation and degradation of forest land caused by urbanization, industrialization and the impact of changes in forestry policies and regulations on forest farmers’ enthusiasm for the forest management are the main driving factors causing changes in regional forest ecological functions. Strengthening the forest management and enhancing forestland protection are the only viable approaches to improving regional forest ecology.