践踏干扰对滇西北高原湿地草甸植物功能性状、多样性与稳定性的影响

The relationship between biodiversity and stability remains one of central topics in ecological field. Although many studies have shown that biodiversity can increase temporal stability, one aspect of stability, other important aspects of stability, such as resistance and resilience, have been less well studied despite the relevance of these aspects of stability for understanding anthropogenic disturbance on ecosystems. Also, the limited number of studies that test the relationship between biodiversity, resistance and resilience have yielded mixing results, all of which severely impede the process of understanding biodiversity-stability relation and associated stabilizing mechanisms. This study will apply trampling experiments onto plateau wetland meadows in Napahai, Bitahai and Shuduhu of southwestern Yunnan province, with the intensity of trampling disturbance manipulated in order to mimic the scenario of ecotourism-related trampling disturbance on such meadows, and to systematically study the impacts of such trampling disturbance on temporal stability, resistance and resilience that represent the major aspects of stability. Meanwhile, a functional-based approach will be applied to help understand characteristics and proportions of different functional traits under the influence of trampling disturbance. Furthermore, functional richness based on functional trait metrics, as well as species richness based on taxonomic classifications, will be used to test their relationship with different stability aspects and to test underlying stabilizing mechanisms. Therefore, this functional-trait approach could help link plant community ecology and functional ecology well, shed light on new methods and approaches that can be used to better understand biodiversity-stability relation and associated stabilizing mechanisms, and provide theoretical basis and scientific evidence for the protection and management of alpine meadow components of plateau wetlands.

物种多样性和群落稳定性的关系一直是生态学研究的一个重要内容。尽管不少研究表明，生物多样性可以促进群落时间稳定性，然而关注生物多样性与稳定性其它度量指标之间关系的研究较少且结果各异，影响了有关多样性-稳定性关系及稳定机制的研究进展。本项目通过对滇西北典型高原湿地纳帕海、碧塔海和属都湖草甸样地施加不同强度的践踏干扰，系统研究干扰对稳定性的三种主要度量指标，时间稳定性、抵抗力稳定性和恢复力稳定性的影响作用，并以干扰作用下草甸植被的功能性状特征为切入点，阐明不同干扰强度下群落功能性状的表达特点与分布格局，分析以功能性状为基础的功能丰富度和以物种形态分类为基础的物种丰富度之间的关系，以及它们对稳定性不同度量指标的影响和作用机制，为深入探讨多样性-稳定性关系和多样性稳定机制提供新的研究思路和方法，并为滇西北高原湿地草甸的保护与管理提供科学依据和参考价值。

滇西北高寒草甸具有重要的生态服务功能，但是旅游业发展带来的游客践踏活动对高寒草甸生态系统带来了严重的影响，而且目前从功能生态学角度系统探讨践踏干扰对高寒草甸植被影响作用的研究也十分有限。本研究以干扰作用下草甸植被功能性状的变化特征为切入点，通过开展模拟践踏实验，系统研究践踏干扰对草甸植被功能性状特征、稳定性和多样性的影响作用。研究结果表明：1）践踏干扰改变了高寒草甸植被的功能性状特征，如减小植株高度和叶面积，以及增加比叶面积和叶干物质含量。践踏干扰期间主要筛选的是与抵抗策略相关的功能性状，而在践踏干扰后的恢复期间主要筛选的是与快速生长策略相关的功能性状；2）践踏干扰影响了高寒草甸植被的物种多样性和功能多样性数量特征。物种多样性方面，植被丰富度水平随着践踏强度的增加而减少，而辛普森和香农多样性指数随着践踏强度的增加而增加。功能多样性方面，功能均匀度和功能分离度随着践踏强度的上升而增加，但功能丰富度对践踏干扰的响应不显著。同时，践踏干扰还显著影响了草甸群落茎叶性状的加权平均值; 3）践踏干扰影响了高寒草甸的抵抗力和恢复力，并且两个稳定性指标间呈负相关关系，这是因为在干扰期和恢复期不同功能性状类型所占的比重发生了变化；4）践踏干扰对高寒草甸植被生产力的影响较为复杂，可能在短期内负面影响植物光合效率的同时缓解物种间的竞争压力，从而促进植被生产力的恢复；5）降雨和土壤养分条件会影响植物功能性状特征，进而影响草甸群落的生态属性和对践踏干扰的响应程度。本研究丰富了功能性状-多样性-稳定性关系的理论维度，并为滇西北高寒草甸的保护与管理提供了科学依据和参考价值。