入侵香蒲枯落物累积对苔草沼泽群落退化的影响机理研究

As one of the main types of marsh in China, Carex-dominated marsh has unique species composition and rich biodiversity. The invasion of cattail species has lead to serious vegetation degradation, threatened ecosystem functions of Carex-dominated marsh for the past few years. Cattail species leave behind abundant litter following senescence during invasion, but little is known about the effect and its mechanism of litter accumulation of invasive cattail species on vegetation in Carex-dominated marsh. In this research, characteristics of litter accumulation are studied during cattail invasion based on the field survey; field controlled experiment is used to study the effects of cattail litter accumulation on the vegetation dynamics; and laboratory simulation of “light-temperature-obstruction” is used to distinguish the importance of the light regulation, temperature regulation, and mechanical resistance of the litter accumulation on the vegetation degradation. The final purpose is to reveal the effects and mechanism of litter accumulation of invasive cattail species on vegetation degradation of Carex-dominated marsh. The research will provide a scientific basis for the Typha control and Carex restoration with proper litter management, and will enrich theory research of species invasion in wetland system.

苔草沼泽是我国最主要的草本沼泽类型之一，具有独特的物种组成和丰富的生物多样性。近年来，香蒲入侵苔草沼泽导致苔草植被严重退化，威胁生态功能。香蒲入侵过程伴随着自身枯落物的大量累积，但其对苔草沼泽植被退化过程的影响及机理尚不明晰。本研究拟通过野外样线调查，明确苔草沼泽香蒲入侵过程中枯落物累积量变化特征；利用香蒲枯落物累积量原位控制实验，阐明香蒲枯落物累积对苔草群落退化过程的影响；并基于“光—温—阻力”三因素交互实验的室内模拟研究，区分香蒲枯落物累积的光、温调节以及机械阻力效应在苔草群落退化中的相对作用，以期揭示香蒲枯落物累积对苔草群落退化的影响与机理。本项目研究成果可为香蒲科学管理与苔草沼泽植被恢复提供科学依据，丰富沼泽湿地系统外来物种入侵机制的理论研究。

近年来，香蒲对苔草沼泽的入侵已经引起了全球范围内部分苔草沼泽生态系统结构和过程的改变，引起苔草沼泽物种丰度与生物多样性减少，导致苔草沼泽群落退化。香蒲入侵过程伴随着自身枯落物的大量累积现象，但其对苔草沼泽植被退化过程的影响及机理尚不明晰。本研究野外调查及控制实验结果表明，未受香蒲入侵干扰前，苔草沼泽群落具有较高的环境异质性，形成多样的群落微生境，进而维持较高的生物多样性。香蒲入侵过程中，香蒲枯落物的大量累积显著改变了群落环境状况，如引起了土壤氮磷养分的富集，同时降低群落光透射率和土壤温度。室内模拟实验表明，苔草对光环境、土壤温度及机械阻力等环境条件变化的适应性低于香蒲。本研究结果表明，香蒲枯落物累积对群落生境的改造使得香蒲在群落竞争中具有优势，进而造成苔草群落结构退化、生物多样性严重下降，最终导致苔草群落退化。本项目研究成果为香蒲科学管理与苔草沼泽植被恢复提供科学依据，丰富了沼泽湿地系统外来物种入侵机制的理论研究。