北京市森林生态安全预警时空差异及其驱动机制

主要探讨森林生态安全预警指数演化的时空格局变化及其驱动力机制,以期为推进北京市森林生态安全决策提供理论参考。基于森林生态安全预警指标体系,运用SD模型从区县尺度对北京市2009—2015年森林生态安全预警的时空差异进行分析,并对2015—2030年森林生态安全演变趋势进行预测。结果表明:(1) 2009—2030年,北京市森林生态安全整体呈改善态势。其中,2009—2015年,北京市森林生态安全预警指数呈略有下降态势,但下降速度有限; 2016—2030年,预警指数呈上升趋势。(2)各区县内部差异显著,5个区县的森林生态安全预警指数有所下降,其中海淀区下降幅度最大。2016—2030年,各区县中除海淀区外,预警指数均小幅上升,森林生态安全状况有所改善;但石景山区仍为巨警,海淀和朝阳区为重警。(3)空间上,森林生态安全预警指数从功能拓展区到城市发展新区及生态涵养区,呈现出由低到高的变化趋势,其低值区随着城市化进程的加快而逐渐扩大。生态涵养区的森林生态安全状况明显优于其他地区,发展新区的森林生态安全改善显著,功能区个别地区则有退化迹象。(4)北京市森林生态安全预警指数时空演变特征主要受森林资源、社会经济、自然环境和林业政策等多种因素的综合影响,因而出现森林生态安全演进的阶段性及其区域性差异。

Spatio-temporal differences and the driving mechanism of early warnings of forest ecological security in Beijing

In this study, we analyzed the spatio-temporal pattern changes and the dynamic mechanism of evolution as a warning index of forest ecological security, to provide a theoretical reference for decision-making in forestry ecological security in Beijing. This study focused on the establishment of an index system as a warning for forestry ecological security. By analyzing spatio-temporal differences from 2009 to 2015 through SD models, a prediction of the evolutionary trend for the ecological security of the forest from 2015 to 2030 was made. The results indicate that:(1) Forestry ecological security will improve from 2009 to 2030 overall. The warning index decreased slightly from 2009 to 2015, but will increase from 2016 to 2030 as predicted. (2) The early warning index decreased significantly in all the five counties and districts, with the Haidian District presenting the sharpest drop. From 2016 to 2030, with the exception of Haidian District, a slight increase can be seen, which shows that ecological security has improved. However, early warnings in the Shijingshan District are still at high levels, and the Haidian and Chaoyang Districts have a severe warning. (3) Spatially, the early warning index demonstrates an upward trend from city function extension zones to new urban development zones followed by ecological conservation zones, and the low index range increasingly expands with urbanization. The security conditions in ecological conservation zones are much better than those in other areas. The early warning index has improved in new urban development zones but has declined in some parts as a function of the extension zone. (4) The spatio-temporal evolution features of the early warning index of forest ecological security in Beijing are significantly affected by many factors, such as forestry resources, social economy, natural environment, and forestry policy, which results in the periodicity and the regional differences of the evolution of forest ecological security.