石羊河下游土壤干层发育及荒漠植被响应研究

Studies on the formation of a Dried Soil Layer and its effect on eco-environment are important issues of soil science as well as ecology．The study area is located in the lower reaches of the Shiyang River in Minqin sand area, which is an ecological strategic place to block the confluence of the Tengger Desert and the Badain Jaran Desert. The desert vegetation has been degraded and dried soil layer is formed due to the shortage of water. the desert vegetation in this area has degraded and the soil dry layer formed，which has affected the effect of vegetation construction and regional ecological stability. Based on the determination criteria of dried soil layer in the sandy area, the effect on the plant growth of water content in soil dried layer studied, and the eco-environmental effects of soil, micro-geomorphology, vegetation and so on to dried soil layer studied under the background of climate change also. The dominant factors, the controllable factors with the dried soil layer development and the influence degree of plant on dried soil layer revealed. The theoretical basis provided for soil dried layer intervention and the evaluation of ecological stability of arid sandy areas.

土壤干层发生机理及其生态环境效应是土壤物理学和生态学及其交叉领域的重要科学问题。研究区域位于石羊河下游民勤沙区，是阻隔腾格里沙漠和巴丹吉林沙漠合拢的生态战略要地。由于水资源短缺，该区荒漠植被进一步退化，下伏土壤形成土壤干层，影响到植被建设成效和区域生态稳定。本项目通过建立沙区土壤干层判定标准，研究土壤干层内水分对植物生长有效性，气候变化背景下土壤干层发育的土壤、微地形地貌、植被等生态环境效应，揭示土壤干层对植物的影响程度、土壤干层发育的主导因子以及可控因子，为土壤干层干预调控、干旱沙区生态稳定性评价提供理论依据。

土壤干层发生机理及其生态环境效应是土壤物理学和生态学及其交叉领域的重要科学问题。研究区域位于石羊河下游民勤沙区，是阻隔腾格里沙漠和巴丹吉林沙漠合拢的生态战略要地。由于水资源短缺，该区荒漠植被进一步退化，下伏土壤形成土壤干层，影响到植被建设成效和区域生态稳定。项目通过梭梭、白刺、沙蒿生理生化指标随土壤水分变化分析了土壤体积含水率与植物生理生化指标的相关性，提出以可溶性糖建立梭梭、白刺、沙蒿抗旱性分级标准，以及加入其它对具体植物敏感性抗旱指标精确分级标准思路；通过不同地貌类型梭梭林地、距离梭梭植株不同距离土壤含水率监测、同位素土壤水分来源及量化、梭梭根部液流、梭梭根系分布特征、气候变化特征研究，明确了研究区基本都存在干层现象，且以中度干层为主，占总测试数量的65.4%，其次为严重干层，占15.4%，轻度干层只占8%的土壤干旱化情况，以及梭梭生长主要依靠天然降水、固定沙丘、黏土滩地影响梭梭生长、梭梭间距大于3.2米有利于梭梭林稳定的认识，从梭梭根区液流、土壤水分来源方面阐明了研究区土壤干层分布的机理；指出了研究区固定沙丘梭梭林地70cm-230cm层次为重度干层，半固定沙丘梭梭林地底部210cm-310cm层次为重度干层、沙丘或沙丘底部梭梭林地存在黏土夹层时多为轻度干层现象、黏土滩梭梭林地黏土部分基本全为重度干层、下部风沙土部分为轻度干层的特征；分析了研究区出干燥度负距平干旱年份超过50%，干旱年份较多，程度较重，加剧了土壤干旱化，为土壤干层发育提供了气候背景的过程；提出了梭梭造林间距大于3.2米，尽量在沙丘下部接近黏土区域造林的建议。为土壤干层干预调控、干旱沙区生态稳定性评价、荒漠植被恢复提供理论依据。