毛乌素沙地灌丛水分利用特征及植被-土壤水分互馈机制研究

Eco-hydrological process and the mechanism underlying the interactions between different factors is a fundamental scientific issue for the ecological recovery in the arid areas. Shrubby patch plays an important role in ecological restoration in semi-arid sandy ecological system. The hydrological process can be affected by the redistribution of the precipitation by root and canopy of shrubs. However, there has been a lack of study on the mechanism underlying the eco-hydrological process between vegetation and soil and its effects on water use features in both individual and community scales. Meanwhile, there is few document touching on the water sharing between shrubs and herbaceous species as well as the implication of water sharing on plant water use feature in Mu Us sandy land. This applied project plans to carry out field and lysimeters experiments in fixed sand land in the southwestern Mu Us Sandy land with the objectives: i) to study the effects of shrubs (Artemisia ordosica, Hedysarum mongolicum Turez and Caragana intermedia Kuang et H.C.Fu) on soil water infiltration rate; ii) to study the water use feature of shrubs (Artemisia ordosica, Hedysarum mongolicum Turez and Caragana intermedia Kuang et H.C.Fu); iii) to explore the phenomenon of so-called hydrological lift in shrubs and its effect on the physiological and growing performances of neighbor herbaceous species; iv) to analyze the factors influencing the eco-hydrological process and interspecific water interaction; v) to reveal the effects of water interactions among vegetation, soil and species on the plant water use features in different scales in Mu Us Sandy land. The findings of this project would promote the development of eco-hydrology and provide theoretical basis for the management of sandy land in semi-arid sandy areas.

生态水文过程及其各要素间互馈机理是旱区生态恢复重建中必须面对的基础科学问题，灌丛植被是半干旱地区沙地生态恢复的重要植被类型，灌木根系及冠层对降水的再分配过程直接影响着植被-土壤系统的水文过程。在毛乌素沙地，灌丛植被与土壤系统相互作用和反馈机理及其对个体及群落水平的水分利用特征影响的研究尚显不足。同时，鲜有研究涉及毛乌素沙地生态系统灌木与伴生草本植物水分共享机制及其对植物水分利用特征的影响。本研究拟在毛乌素沙地固定沙地设置灌丛群落研究样地并开展蒸渗仪栽培试验，研究油蒿、杨柴和中间锦鸡儿对土壤水分入渗性能的影响以及灌丛不同尺度植物水分利用特征，探讨灌木水力提升作用及其对伴生草本植物水分生理状况的影响，辨析灌丛生态水文及种间水分关系的影响因素，揭示毛乌素沙地灌丛植被-土壤及植物种间水分互馈对植物不同尺度水分利用特征的影响，促进半干旱沙地生态水文学的发展，为半干旱沙地治理提供理论依据。

在国基金项目经费资助下，在毛乌素沙地西南缘建设了固沙灌木监测样地，采用酸性品红标记示踪、稳定同位素技术和现代生理生态研究方法，研究了毛乌素沙地不同生境下杨柴的克隆生长及其水分生理效应，中间锦鸡儿、油蒿和杨柴水分生理和灌丛土壤水平收支状况以及三种灌丛对降雨的再分配及其富集效应。结果表明，中间锦鸡儿的单叶水分利用效率最高，杨柴的最低。土壤储水量和土壤蒸散量都表现为中间锦鸡儿最小，杨柴最大。植物水分利用效率三种灌丛之间均有显著差异，中间锦鸡儿最大，油蒿最小。.水分异质性生境下，杨柴母株向子株的色素运输速率＞母株自运输速率。水分一致性生境下母株的运输范围大于子株。在水分异质生境下，子母株相连的根茎被切断后，克隆子株对水分更加敏感，更趋于利用含水量较高的土层水分。在3种不同生境下，克隆母株到子株的色素运输速率与克隆子株的水分状况显著正相关，克隆子株到母株的色素运输速率与克隆母株的蒸腾速率、气孔导度显著正相关关。.灌木茎干流量、茎流率、穿透雨量和穿透雨率均表现为杨柴>中间锦鸡儿>油蒿。降雨强度与杨柴、中间锦鸡儿和油蒿灌木的茎流量、茎流率、截留量和截留率均正相关。三种灌木的截留量与冠幅面积呈显著的正相关关系。 杨柴、中间锦鸡儿和油蒿这三种灌木的汇流率均与降雨量和降雨强度存在极显著正相关关系。三种灌木茎干流均具有增补土壤水分的功能，杨柴对雨水的汇流效应显著高于其他两种灌木。.项目经过四年多的研究，提出了应用碳、氢、氧稳定同位素技术、色素标记等研究旱区沙生灌木水分利用特性的方法体系，为研究旱区沙灌木应对复杂多变环境的机制提供了系统的研究方法。共发表12篇论文，出版专著1部，授权实用新型专利1个，培养研究生4名。