祁连山高寒灌-草群落交错区界面特征及响应不同放牧干扰的生态过程

Under the global climate change background, herbivore grazing and other human disturbance have led the rapid degradation of the fragile alpine vegetation and ecological degeneration on the Tibetan Plateau as well as in the vicinity region. The studies about alpine mountain vegetation ecotone have become a research hotspot in recent years owing to their special ecological features of earlier climate change warning and sensitive response to human disturbance. The project will take the shrubland-grassland ecotone of rhododendron shrubland which has special ecological service function and the alpine meadow which is the dominant vegetation in Qilian Mountains as a breakthrough point by applying the principles and methods of Community Ecology and Grazing Ecology, and combination of aboveground and belowground ecological means to study the interface features of ecotone between rhododendron shrubland and alpine meadow, and to reveal mechanism of the ecotone interface for mosaic pattern formation and habitat heterogeneity maintaining based on ecotone interface population competition and ecological adaptation studies, and understanding the impact ways of grazing to ecotone community pattern and function, as well as the aboveground and underground key processes of ecotone interface response to different grazing disturbance. The study will building the ecological processes model of response to different grazing patterns based on the relationship of key species and habitats interaction among ecotone interface. The research results will be helpful for us to explore ways to accelerate reconstruction and ecological functions rehabilitation of rhododendron shrubland, and will also greatly benefit to heterogeneous vegetation management and sustainable utilization, and provide the solution strategies for the alpine vegetation degradation restoration, meanwhile, try to explore the early ecological warning function of alpine ecotone at regional scale.

在气候变化背景下，放牧等人为干扰加剧了青藏高原及周边高寒脆弱植被的退化和生态恶化。高寒山地植被交错区因具有敏感响应人为干扰和预警气候变化的特殊功能成为近年的研究热点。本项目以祁连山地区特色植被杜鹃灌丛和优势植被高寒草甸之间的群落交错区为切入点，应用群落生态学和放牧生态学的基本原理与方法，地上与地下生态有机结合，研究杜鹃灌丛-高寒草甸群落交错区的界面特征，解析界面效应，通过群落交错区界面种群竞争与生态适应，揭示群落交错区界面镶嵌格局形成与异质性生境维持的机制，明确放牧影响灌-草群落交错区群落格局与功能的途径，以及交错区响应不同放牧干扰的地上、地下关键过程，构建交错区界面关键种与生境互作响应不同放牧模式的生态过程模型，探讨加速杜鹃等优势灌木恢复及群落功能重建的途径，以期为高寒地区群落异质性生境管理及生态恢复提供依据。

本项目以祁连山地区特色植被杜鹃灌丛与高寒草甸之间的群落交错区为切入点，应用群落生态学与放牧生态学基本原理与方法，地上与地下生态有机结合，研究群落交错区的界面特征，揭示群落交错区界面镶嵌格局形成与异质性生境维持的机制，明确放牧影响灌-草群落交错区群落格局与功能的途径，获得了如下研究结果和结论。1）研究并明确了祁连山地区杜鹃灌丛与高寒草甸之间的群落交错区的地上群落与地下土壤界面梯度特征，分析了界面稳定维持的机制；2）将杜鹃灌丛及边缘地带的的16种灌木划分为8类地下根构型，用生态位分离与重叠理论解释了杜鹃灌丛16种灌木的地下根系垂直生态位特征，并对气候变化及人为干扰下，灌丛群落的演替进行有效预测；3）研究了灌丛建群种4种杜鹃的株丛特征、生长特性及年轮特征，探讨了杜鹃径向生长与不同气候因子间的关系；4）研究了高寒杜鹃灌丛与草甸群落过渡带植被及土壤系统对不同放牧强度（轻度、中度、重度）及相应的围封恢复的响应；5）采用磷脂脂肪酸（PLFA）分析方法及Illumina Miseq高通量测序技术，分析了不同强度放牧及相应的围封恢复处理，对灌丛草地土壤微生物菌群结构及多样性的影响；6）研究了禁牧、全生长季休牧、夏季休牧和连续放牧对高寒草甸群落、地下生物量、土壤理化特性、土壤碳氮贮量、土壤呼吸及其动态的影响。基于以上研究，探讨了灌-草群落交错区响应不同放牧模式的关键生态过程，获得高寒地区灌丛－草甸异质性植被景观适应性生态管理及杜鹃灌丛生态恢复的技术依据。项目实施期间，共发表学术论文19篇（其中SCI论文2篇，CSCD期刊论文15篇）；获授权发明专利1项，申报实用新型专利1项；完成相关研究的硕士学位论文3篇，1篇博士学位论文在本项目的前期研究基础上，进行进一步研究。