青藏高原高寒草甸生态系统对冰冻圈要素变化的响应研究

In the context of global climate change, the study on the ecological effect of cryospheric change has emerged as an international hot field and frontier project, and the attention degree is increasing. To address this problem, a comprehensive observation field of alpine meadow ecosystem will be selected as an experimental plot in the source regions of the Shule River in the northeastern margin of the Qinghai-Tibet Plateau (QTP). And then, the in-situ monitoring with meteorological factors (air temperature and humidity, wind speed and wind direction, precipitation and pressure, etc.), soil environment (physicochemical properties, organic carbon density, microbes and CO2 flux), vegetation features (community composition and structure, biomass and greenup) and cryospheric elements (permafrost and snow cover) will be implemented persistently in almost ten years. The objectives of our project will be to reveal the coupling response of permafrost and snow cover to climate change, and their impact degree, processes and the controlling factors on soil water-heat-salt processes, carbon sequestration potential, source-sink effects, biological (plant and microbial) diversity, plant phenology and productivity. Furthermore, the response processes and internal coupling mechanisms of alpine meadow ecosystem to the changes of cryospheric elements will be systematically illuminated under the regional climate change. Our project aims to fill a gap of in-situ observation research in the QTP, to establish a solid scientific foundation for the evaluations of vulnerability, service function and future scenario of alpine grassland ecosystem, and to provide feasible theoretical basis and practical reference for eco-environmental conservation, restoration and sustainable development in the QTP.

全球气候变化背景下，冰冻圈变化的生态效应研究已成为一项国际性的热点领域和前沿课题，其重视度与日俱增。本项目拟以青藏高原东北缘疏勒河源一处高寒草甸生态系统观测场为试验样地，开展气象要素（风温湿压等）、土壤环境（理化特性、有机碳密度、微生物和CO2通量）、植被特征（群落组成结构、生物量和返青期）和冰冻圈要素（多年冻土和积雪）近10年的定位监测研究，以量化揭示多年冻土和积雪对气候变化的耦合响应特征及其对土壤水热盐过程、固碳潜力、源汇效应、生物（植物和微生物）多样性、植物物候和生产力的影响程度、过程和主控因素，进而系统阐明区域气候变化条件下高寒草甸生态系统对冰冻圈要素变化的响应过程和内在耦合机制。旨在填补青藏高原相关研究的空白，为高原高寒草地生态系统脆弱性和服务功能评价及未来情景预估奠定良好的科学基础，也为高原生态环境保护、修复及可持续发展提供切实可行的理论依据和实践参考。

全球气候变化背景下，冰冻圈变化的生态效应研究已成为一项国际性的热点领域和前沿课题，其重视度与日俱增。本项目以青藏高原东北缘疏勒河源多年冻土区为研究区并以一处高寒草甸生态系统观测场为试验样地，主要开展高寒草地生态系统对多年冻土变化（多年冻土退化和冻融过程）的响应研究，结果表明：过去20（2001-2020）年来疏勒河源年均气温与年降水量分别以0.01 ℃·a-1和4.35 mm·a-1的速率增加，多年冻土重度退化阶段对气候变化响应的敏感程度强于轻度和中度退化阶段；高寒草甸活动层土壤冻融过程中冻融期提升了微生物群落丰富度、稳定性和多重多样性与土壤多功能性之间的关系以及温室气体排放，冻融强度是温室气体排放的主控因素，微生物多重多样性显著影响N2O排放通量；高寒草地逆向演替过程中，群落构建以随机组装过程为主导；多年冻土退化下的活动层土壤微生物稳定性下降和碳损失紧密关联。上述研究可望对青藏高原多年冻土变化下的微生物群落演化过程和碳动态的微生物机制探究以及生态系统服务功能评估与提升提供科学参考。