有性繁殖体凋落物输入对热带雨林整体凋落物分解的激发效应----以西双版纳热带雨林为例

There are few studies which have involved the ecological role of sexual propagul litterfall (SPL) in the home-field advantage of forest litter decomposition. The average ratio of SPL to total litterfall biomass in the tropical forests is much higher than that in other forest types, In particular, the SPL averagely contains up to 23% of the total phosphorus of the total litterfall, which may have important ecological functions for the tropical rainforests, as the commonly phosphorus deficient view. Since there are significant home-field advantage in litter decomposition, it is necessary for us to study the ecological function of SPL in the home-field advantages of the total litter decomposition in the tropical rainforest. In this proposal, we choose the typical tropical seasonal rain forest in Xishuangbanna as the case, based on the hypothesis that SPL can regulate the home-field advantages of tropical rainforest litter decomposition by changing the overall litter nutrient stoichiometry and stimulate the microbial activity (priming effect) of the litter detritusphere at the early home field litter decomposition stage, by establishing an home-field advantage associated database of "SPL→microorganisms→litter decomposition" in tropical rain forest, to study the ecological function of SPL in the home-field advantage of tropical rainforest litter decomposition, to clarify the intrinsic regulatory pathways and mechanisms, and to analysis the temporal and spatial differences of SPL ecofunctions based on the indices of the effect distance and the excitation time curve. Through this study, we hope to maintain and provide more fundamental theoretical supplement for the tropical rainforest litter decomposition and forest nutrient autotrophic mechanisms in Xishuangbanna and other tropical areas.

迄今很少有研究涉及花果等节律性有性繁殖体凋落物（SPL）在森林整体凋落物分解主场效应中的生态学角色。热带森林SPL与总凋落物量的平均比例远高于其他林型，特别是其含有的磷元素占凋落物总磷的比例竟高达23.0%，这对普遍缺磷的热带雨林而言，可能存在重要的生态功能。既然凋落物分解存在明显主场效应，我们有必要在热带雨林开展SPL在整体凋落物分解主场效应中的生态功能研究。本项目以西双版纳热带季节雨林为研究对象，基于“SPL可以通过调控热带雨林整体凋落物的化学计量特征以及激发主场微生物的分解活性”这一科学假设，建立热带雨林凋落物分解主场效应的“SPL激发→主场微生物介导→凋落物主场效应”调控机理关联数据库；探究SPL在热带雨林凋落物分解主场效应中的生态功能；阐明其内在调控途径和机制；基于效应距离和作用时间曲线探讨激发效应的时空差异，以期为西双版纳热带雨林凋落物分解与森林维持自养的内在机制提供理论补充。

花果等节律性有性繁殖体凋落物（SPL）在森林整体凋落物分解主场效应中的生态学角色，我们了解不多。热带森林SPL与总凋落物量的平均比例远高于其他林型，特别是其含有的磷元素占凋落物总磷的比例竟高达23.0%，这对普遍缺磷的热带雨林而言，可能存在重要生态功能。既然凋落物分解存在明显主场效应，我们有必要在热带雨林开展SPL在整体凋落物分解主场效应中的生态功能研究。本项目以西双版纳热带季节雨林为研究对象，基于“SPL可以通过调控热带雨林整体凋落物的化学计量特征以及激发主场微生物的分解活性”这一科学假设，建立热带雨林凋落物分解主场效应的“SPL激发→主场微生物介导→凋落物主场效应”调控机理关联数据库，开展SPL生态功能研究。我们发现，西双版纳热带季节雨林林下主场环境和林窗客场环境下，凋落物碎屑周际微生物群落结构组成大体一致，但相对丰度存在明显差异；变形菌门是凋落物分解过程中的优势菌门；林下主场环境的碎屑周际微生物群落丰富度指数、多样性指数高于林窗客场环境；温度湿度光照强度等环境因子对碎屑周际微生物群落结构有显著影响；含有性繁殖体的凋落物中碎屑周际微生物的丰富度和多样性指数高于去除有性繁殖体的凋落物；有性繁殖体的输入在凋落物分解过程中对碎屑周际微生物活性有激发效应，但林窗的产生又一定程度上消弱了其激发效应；在热带雨林主场环境和橡胶林客场环境中，凋落物碎屑周际微生物的群落结构组成并未发生明显变化。主客场环境下凋落物碎屑周际微生物各优势菌门变化幅度较小，微生物群落多样性指数在主客场均未表现显著性差异；冗余分析表明环境因子中的光照、温度、湿度与微生物群落物种丰度具有明显的相关性，温度与湿度对微生物群落分布的相关性更为明显。凋落物的微生物群落丰度在两种主客场环境下无显著性差异。该研究初步阐明了SPL在热带雨林凋落物分解主场效应中的生态功能和内在调控机制；探讨了SPL产生的激发效应的时空差异，为西双版纳热带雨林凋落物分解与森林维持自养的内在机制提供了一定的理论补充。