Complementarity in water sources among dominant species in typical steppe ecosystems of Inner Mongolia, China
Complementarity in water sources among dominant species in typical steppe ecosystems of Inner Mongolia, China
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DOI：
10.1007/s11104-010-0307-4
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发表时间：
2011-03
期刊：
影响因子：
4.9
通讯作者：
Hao Yang;K. Auerswald;Yongfei Bai;Xingguo Han
中科院分区：
文献类型：
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作者：
Hao Yang;K. Auerswald;Yongfei Bai;Xingguo Han
水分是干旱半干旱草地植物生长、初级生产力和生态系统稳定性的重要控制因子。在此，我们进行了为期2年的实地研究，以探讨冬半年（即10月至4月）和夏季降水（5月至9月）对内蒙古典型草原生态系统中共存植物物种生长的贡献。在以大针茅、小叶锦鸡儿和羊草为优势种的3个草原群落中，分别测定了土壤水和优势种植物茎水的氢稳定同位素比值、土壤水分和植物水势。从冬季半年降水的水的分数是一个重要的水源，贡献45%，植物总水分吸收在干燥的夏季后，潮湿的冬季（2005年）和15%，在夏季底土水分已被利用在前一年（2006年）。在物种水平上，小叶锦鸡儿完全可以获得深层土壤水，这些水可以通过冬季降水补充，而糙隐子草完全依赖夏季降雨。赖草、冰草和大针茅表现出资源依赖型水分利用策略，在深层土壤水充足时利用深层土壤水，在底土水被开发后转向雨水。我们的研究结果表明，在这些半干旱生态系统中，植物之间的水源分化提高了土壤水的利用率，减少了种间对水的竞争。共存物种在水源中的生态位互补性可能是高多样性群落具有高生产力和高抗旱能力的潜在机制。
Water is the most important factor controlling plant growth, primary production, and ecosystem stability in arid and semi-arid grasslands. Here we conducted a 2-year field study to explore the contribution of winter half-year (i.e. October through April) and summer precipitation (May through September) to the growth of coexisting plant species in typical steppe ecosystems of Inner Mongolia, China. Hydrogen stable isotope ratios of soil water and stem water of dominant plant species, soil moisture, and plant water potential were measured at three steppe communities dominated byStipa grandis, Caragana microphylla, andLeymus chinensis, respectively. The fraction of water from winter half-year precipitation was an important water source, contributing 45% to plant total water uptake in a dry summer after a wet winter period (2005) and 15% in a summer where subsoil moisture had been exploited in the previous year (2006). At species level,Caragana microphyllaexhibited a complete access to deep soil water, which is recharged by winter precipitation, whileCleistogenes squarrosacompletely depended on summer rains.Leymus chinensis, Agropyron cristatum, andStipa grandisshowed a resource-dependent water use strategy, utilizing deep soil water when it was well available and shifting to rain water when subsoil water had been exploited. Our findings indicate that differentiation of water sources among plants improves use of available soil water and lessens the interspecific competition for water in these semi-arid ecosystems. The niche complementarity in water sources among coexisting species is likely to be the potential mechanism for high diversity communities with both high productivity and high resilience to droughts.