气候变化背景下高寒草甸区根系变化特征及其对关键土壤水分参数的影响机理

Alpine meadows are special products in Qinghai-Tibet Plateau, with root biomass accounting for more than 80%. The change of their root has a significant influence on the temporal and spatial distribution of soil moisture. Climate warming affects the characteristics of humification and retention of alpine meadow root, and then influences soil moisture in alpine region. Focusing on key scientific issues such as “the mechanism of climate warming on the characteristics of alpine meadow root changes” and “the mechanism of root system changes on soil moisture parameters in alpine meadows”, this project chooses the alpine meadows in the Naqu basin as the research object. Based on substantial preliminary work, the study will be carried out with key support of field prototype observation experiments and indoor control experiments, and combining with simulated warming technology, minirhizotron technique, and CT technology. The objectives are to ascertain the impact of climate change on the characteristics of root changes in alpine meadows, to analyze the change impact of root system on the microstructure of soil aggregates, and then to recognize the mechanism of the interaction between roots and soil microstructure on key soil moisture parameters, finally to establish the functional relation among “root system- soil microstructure- key soil moisture parameters”, which can provide basic data, theoretical and technical support for the identification of water cycle evolution mechanism in alpine basins. The team has solid preliminary work basis, meanwhile the research plan is reasonable and feasible.

高寒草甸根系生物量占总生物量的80%以上，根系的动态变化对土壤水分特性影响十分显著。以“温升”为背景的气候变化，改变了高寒草甸根系的腐殖化及存留特性，已对高寒区土壤水分特征参数产生了显著影响。本项目将围绕“气候变暖对高寒草甸根系变化特征的影响机理”和“高寒草甸根系变化对土壤水分参数的影响机理”等关键科学问题，以那曲流域高寒草甸为研究对象，在大量前期工作基础上，以野外原型观测实验和室内控制实验为关键支撑，融合模拟增温技术、微根窗技术和CT扫描技术，探明气候变化对高寒草甸根系变化特征的影响，分析根系变化对土壤团聚体微结构的影响，进而识别根系与土壤微结构协同变化对关键土壤水分参数的影响机理，并构建三者之间的函数关系，可为高寒流域水循环演变机理识别提供基础数据与理论技术支撑。申报团队前期工作基础扎实，研究方案合理且具可行性。

本项目围绕“气候变暖对高寒草甸根系变化特征的影响机理”和“高寒草甸根系变化对土壤水分参数的影响机理”等关键科学问题，以那曲流域高寒草甸为研究对象，融合模拟增温技术与微根窗技术，识别了气候变化背景下高寒草甸区根系变化特征及其对关键土壤水分参数的影响机理。主要取得了以下4方面的研究成果：1）建成了高寒草甸增温响应实验场，获取了高寒草甸根系及土壤特征关键参数；2）分析了高寒草甸根系分布特征及对气候变暖的响应，提出了高寒草甸根系形态分布与土壤温湿度之间的响应关系；3）构建了高寒草甸根长与根尖密度函数，改进了高寒草甸根系吸水模型并分析了根系吸水特性；4）构建了高寒流域分布式水文模型，识别了高寒草甸根系吸水规律变化对植被蒸腾和土壤水分的影响。在项目研究过程中，发表学术论文23篇，其中SCI论文18篇；授权发明专利11项、软件著作权1项；获省部级一等奖2项和创新团队奖1项；1人次获国家级荣誉称号，培养博士研究生5名、硕士研究生3名。通过本项目研究，将进一步发展高寒草甸区产汇流理论与模拟技术，为保障水安全与适应气候变化提供基础数据与理论技术支撑。