亚高山针叶林林窗对倒木分解及其附生植物群落的影响

Both log decomposition and the community succession of epiphytic plants play important roles in ecosystem functions such as fertility maintaining, biogeochemical cycles and water conservation, which are influenced by gap-induced microenvironmental conditions. As yet, little information has been available on the relationships between log decomposition and epiphytic plant community succession, and these processes in respond to forest gap. Therefore, it is hypothesized that forest gap not only gives strong effects on log decomposition process, and colonization and succession of epiphytic plant community simultaneously, but also alters the interactions of these two ecological processes, which in turn manipulates the whole process of log decomposition and biodiversity of epiphytic plant community. Based on an optimized method of decomposition time series and chronosequence, a 4-year log decomposition experiment combined with log epiphytic plants removal will be conducted in the subalpine coniferous forest of western Sichuan. We will focus on the decomposition process of Minjiiang fir (Abies faxoniana) log and its relationships with epiphytic plant community succession, the effects of forest locations on the decomposition process and epiphytic plant community succession of different decaying stages of Minjiang fir logs, and the effects and mechanisms of log epiphytic plants (e.g., lich and bryophytes) on log decomposition in the subalpine coniferous forest. It will be expected to understand the effects and their mechanisms of forest gap regeneration on log decomposition, and to illustrate the interactions between log decomposition process and epiphytic plant community succession. The results might provide crucial scientific basis for understanding subalpine forest ecosystem process and for sustainable forest management.

倒木分解及其相联系的附生植物群落演替在地力维持、生物元素循环、水源涵养等方面具有重要生态功能，并受到林窗控制的微环境的影响。然而，已有研究很少关注倒木分解与附生植物群落的关系及其对林窗的响应。因此，基于“林窗不仅同步影响倒木分解及其附生植物群落的定居和演替，而且改变了这两个生态学过程的相互联系，最终决定了整个倒木分解过程和倒木附生植物群落的多样性”的科学假说，拟以川西亚高山针叶林为研究对象，采用年龄序列与时间系列相结合的倒木分解实验和倒木附生植物去除实验，重点研究亚高山针叶林岷江冷杉倒木分解过程及其联系的附生植物群落演替，林窗位置对不同腐烂等级的倒木分解过程及其附生植物群落演替的影响，附生植物对倒木分解的作用机制，理解林窗更新对倒木分解的影响机制，揭示倒木分解过程与附生植物群落演替的内在联系。研究结果可为深入理解亚高山针叶林生态系统过程和森林可持续经营与管理提供关键证据。

林窗对倒木分解过程、倒木附生植物群落演替及其交互作用的影响可能显著影响森林生态系统物质循环和生物多样性，但缺乏深入系统地研究。因此，本项目以川西亚高山针叶林为研究对象，采用年龄序列与时间系列相结合的倒木分解实验和倒木附生植物去除实验，研究了亚高山针叶林林窗对岷江冷杉（Abies faxoniana）倒木分解过程及其附生植物群落的影响。主要研究内容：（1）岷江冷杉倒木分解过程及其附生植物群落演替；（2）林窗位置对不同腐烂等级倒木分解过程及其附生植物群落演替的影响机制；（3）附生植物去除对倒木分解的影响机制。重要结果和关键数据：（1）倒木树皮、边材和芯材具有不同的分解模型，倒木分解过程表现为碳、纤维素和木质素的释放过程以及腐殖质、氮、磷的累积趋势；（2）倒木附生植物群落的物种丰富度、多样性和生物量随着分解而增加，高腐烂等级的倒木附生植物群落与地表苔藓植物群落的相似度较高；（3）林窗位置和附生植物去除对岷江冷杉倒木分解过程、腐殖化、碳氮磷释放、木质素和纤维素降解等会产生不同程度的影响，林窗位置和附生植物去除对树皮分解以及高腐烂等级的边材和芯材分解的影响更显著；（4）相近腐烂等级的倒木微生物群落相似度较高，优势类群为子囊菌、担子菌、变形杆菌和酸杆菌，倒木微生物多样性随着腐烂程度增加而表现为先增加后降低的趋势；（5）林窗和附生植物去除及其交互作用对倒木微生物群落结构和多样性会产生不同程度的影响，树皮的微生物群落结构和生物量对附生植物去除和林窗位置的响应更敏感，细菌群落对附生植物去除和林窗位置的响应更敏感。这些结果表明，亚高山针叶林林窗更新和倒木附生植物通过影响倒木分解环境以及微生物群落结构和多样性，从而影响森林生态系统物质循环和生物多样性，研究结果为亚高山针叶林可持续经营与管理提供了重要科学依据。研究成果在国内外主流学术期刊学术论文29篇（SCI 21篇），培养毕业博士、硕士13名。

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