太平洋西北部地区天然林景观动态及破碎化驱动力分析

【目的】准确量化森林破碎化程度以及破碎化过程,对于理解森林的生境变化导致的生态服务功能变化具有重要作用。本研究旨在量化美国西北部天然林破碎化空间过程,探究其社会经济驱动因素,为构建合理的森林经营方案提供参考,并为提高中国东北地区天然林的管理水平提供借鉴。【方法】利用美国国家土地覆盖3期数据(NLCD2008、2013及2016),先对太平洋西北部地区天然林进行景观格局分析,然后采用森林破碎化过程模型描述和量化了4种破碎化过程,据此刻画了研究区内天然林景观动态变化及破碎化的时空模式。结合社会经济统计资料,分析导致这些变化的社会经济驱动因素及其管理含义。【结果】①2008—2016年,天然林面积总体呈现出缓慢的上升趋势,森林损失面积持续低于森林恢复面积,森林斑块面积逐渐增大,而斑块数量逐渐减少,森林连接性逐渐提高。②森林破碎化现象广泛存在,且随着时间推移逐步得到改善,收缩和破碎化过程在森林破碎化成分中占主导地位,4种破碎化过程呈现出“破碎化—收缩—穿孔—消失”的前后关联。③社会经济因素是森林破碎化的重要预测因子, 表现形式为:人口增加、居民点建设、农业开垦种植和区域经济发展对森林资源的依赖等。【结论】近10年内太平洋西北部森林破碎化程度逐渐降低,受人为干扰影响较大,森林景观在研究阶段内未发生明显变化,既满足了木材工业发展的需要,又符合生态保护的要求。

Assessing natural forest fragmentation process dynamics and its drivers in the Pacific northwest region,USA

【Objective】 The accurate quantification of forest fragmentation severity and fragmentation processes plays an important role in understanding the dynamics of ecological service functions induced by habitat changes. This analysis quantified the spatial process of forest fragmentation in the Pacific northwest region, USA, and explored the socioeconomic driving forces contributing to the fragmentation process, thereby providing a reference for formulating a reasonable forest management plan in similar regions. It is of great significance to learn from the advanced philosophy of natural forest management as a reference with which to effectively improve the management of natural forests in northeastern China. 【Method】 Based on a triple-date national land cover database (NLCD), including NLCD2008, NLCD2013 and NLCD2016, with a spatial resolution of 30 m, forest landscape patterns were first analyzed using landscape indices, followed by a forest fragmentation process model to characterize four fragmentation processes of the deforested patches to reveal the dynamics of the natural forest fragmentation pattern. Next, the socioeconomic drivers responsible for the observed forest fragmentation dynamics and their management implications were examined. 【Result】 ① From 2008 to 2016, the overall natural forest area showed a slight increasing trend and the forest loss area continued to be lower than the forest recovery area. The mean patch area of forest gradually increased, whereas the number of patches gradually decreased, indicating that forests connectivity gradually improved. ② Forest fragmentation was widespread in the region and gradually decelerated over time; the subdivision and shrinkage components dominated the entire fragmentation processes, and an apparent successive sequence, subdivision-shrinkage-perforation-attrition, was clearly observed in the fragmentation process maps. ③ Forest fragmentation was primarily driven by local socioeconomic factors, particularly the dependency of population growth, residential construction, agricultural expansion and economic booms on forest resources. 【Conclusion】 In the past 10 years, the forest fragmentation level in the Pacific Northwest, which has been greatly affected by human disturbance, has been gradually reduced. Additionally, the forest landscape did not change substantially during the study period. Regional forests not only met the needs for timber industry development but also met the requirements of ecological conservation.