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引言林窗(gap)是森林群落中老龄树木死亡或因各种干扰因素(如干旱、台风、火灾等)导致优势树木死亡,从而在林冠层造成空隙(已有文献报道空隙大小为4—1000 m~2)的现象。林窗是森林生态系统中最普遍、最重要的小尺度干扰,是森林生态系统更新演替的驱动要素,更是森林结构和功能维持的重要因子。基于林窗发展的森林循环理论对森林经营与管理具有重要的理论与实践指导意义。因此,林窗研究一直是林学相关领域的研究热点。然而,由于林窗演化的长期性和动态性,关于林窗结构特征、林窗环境异质性及林窗更新规律等科学问题又是研究的难点。在国家自然科学基金面上基金项目“次生林
INTRODUCTION Gaps are the dead trees in forest communities or the dying of dominant trees due to various disturbances such as droughts, typhoons, fires and the like, resulting in voids in the canopy (gaps have been reported in the literature of 4-1000 m ~ 2) phenomenon. Forest gap is the most common and important disturbance of small scale in forest ecosystem. It is also the driving factor of forest ecosystem renewal succession and the important factor of forest structure and function maintenance. Forest circulation theory based on gap development has important theoretical and practical guiding significance to forest management and management. Therefore, Gap research has always been a hot topic in the field of forest science. However, due to the long-term and dynamic evolution of the gap, scientific issues such as the structural features of the gap, the heterogeneity of the gap environment and the rules of the gap closure are yet to be studied. In the National Natural Science Foundation of fund projects ”secondary forest