半干旱典型固沙灌木水分调控机理及其对干旱胁迫与持续降水的响应

The semi-arid area is a sensitive area under climate change. The composition of the vegetation structure is relatively simple and the ecological environment is fragile. As an important part of its ecosystem, shrubs can play a role in fixing sand and preventing desertification. Taking the special landforms, vegetation types and the soil environment into consideration, this proposed project will study on three types of sand-fixing shrubs in the dune-meadow ecotone area of the Horqin Sandy Land, i.e., Caragana microphylla, Salix gordejevii and Artemisia halodendron. Using the stemstream observation system which based on the principle of heat balance and the ground hyperspectral spectroradiometer, a new method for modeling the dynamic coupling process of water consumption and carbon accumulation of individual shrub will be created. The methods of evapotranspiration model and high-resolution remote-sensing technique will also be combined used to expand the spatial scale to the community scale. This proposed project is focusing on: (1) revealing water use strategy and the water regulation mechanism of the shrubs and their responses to the drought stress and sustained precipitation events, (2) analyzing the variation of water use patterns and regional differences in different shrub communities under these two extreme scenarios, and (3) expounding the succession mechanism of different shrub communities based on water use strategy and regulation theory driven by extreme events. The results will be able to provide a basis for studying the response of sandy land vegetation to climatic conditions in arid areas, and it is of great significance for managing the water resources in sandy areas, predicting future vegetation changes, and assessing the ecological sustainable development of arid areas under the trend of climate warming and drying.

半干旱区作为气候变化的敏感区，植被结构组成相对简单，生态环境非常脆弱。灌木植被作为其生态系统的重要组成部分，能起到改造沙地，防治荒漠化的作用。本项目以科尔沁沙丘-草甸相间地区为研究区，综合考虑特殊的地形地貌、植被类型以及土壤环境，以固沙先锋灌木小叶锦鸡儿、黄柳和差巴嘎蒿为研究对象，利用基于热平衡原理的茎流观测系统与地物高光谱仪，建立单株灌木水消耗-碳积累动态耦合过程模拟方法，再结合蒸散发模型与高分辨率遥感进行群落尺度扩展，重点揭示灌木水分利用策略及其对干旱胁迫与持续降水的响应和调控机理，辨析两种极端情境下不同灌木群落水分利用变化规律和区域差异，阐释极端事件推动下基于水分利用策略与调控理论的灌木群落演替机制。成果可为干旱区沙地植被对气候条件的响应研究提供本底依据，对管理沙区水分、预测未来植被变化以及评价气候暖干化趋势下干旱区生态可持续性建设具有重要意义。

半干旱地区生态系统较为脆弱，植被对水分条件变化敏感，空间上往往呈现斑块状。灌木植被作为半干旱区生态系统的重要组成部分，改造沙地、防治荒漠化作用重大。本项目以科尔沁沙丘-草甸相间地区为研究区，综合考虑地形地貌、植被类型以及土壤环境，开展了“空-天-地”生态水文综合观测与试验，丰富了科尔沁沙丘-过渡带-草甸地区遥感多尺度监测体系；对典型固沙灌木斑块状群落进行了精细划分，揭示了其演变规律；辨析了干旱胁迫与持续降水下典型固沙灌木蒸散发及其组分变异规律，建立了典型草甸区地上生物量高光谱遥感模型，并对其适用性进行了评价；探明了不同类型土壤水分输移及气体渗透规律，揭示了不同类型沙丘土壤—植被组合单元灌木根区水分利用机制，明晰了典型固沙灌木蒸散发对干旱胁迫及持续降水的响应。.本项目执行期间，在国内外高水平学术期刊上发表论文8篇，其中SCI论文1篇，CSCD论文7篇；申请发明专利1项；登记软件著作权3项；培养硕博士研究生6名，本科生1名；参加国内学术会议和专题研讨会4次，协助承办国内学术会议1次，参加国际国内联合研究研讨会1次；绘制了试验区典型植被群落精细划分图，收集并初步建立了科尔沁沙地典型固沙灌木茎干液流、生物量、高光谱试验观测数据集。.本研究能为沙区植被对气候条件的响应提供本底依据，对管理半干旱沙区重要植物资源、有效利用沙地水分、预测未来植被变化以及评价气候暖干化趋势下半干旱区生态可持续性建设具有重要意义。