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Water is the most critical factor for controlling the vegetation pattern in arid and semiarid regions. Using a dye-tracing experiment, we analyzed the infiltration pattern beneath shrub canopy and interspace grass patches in typical steppe ecosystems. The dye coverage, uniform infiltration depth, maximum infiltration depth, total stained area and heterogeneous infiltration stained area were measured by two indices, the maximum infiltration depth index (MIDI) and heterogeneous infiltration index (HII), which were calculated by processing dye-stained photos. The MIDI and HII of soil under shrubs were 1.41±0.14 and 0.29±0.068, respectively, and larger than those of grass soil, 1.26±0.14 and 0.20±0.076. Using the MIDI, HII, field soil moisture and rainfall data, the infiltration depth and heterogeneous infiltration amount for 26 nature rainfall events were calculated. The results imply that water can infiltrate to a deeper layer beneath shrub canopy than beneath grass patches and that more water infiltration occurs beneath shrub canopy than beneath grass patches. These results are of prime importance for arid and semiarid ecosystems with a limited water supply due to high evaporation and low precipitation. 相似文献
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内蒙古典型草原土壤及其水文过程对灌丛化的响应 总被引:6,自引:2,他引:4
基于野外观测和室内试验相结合的方法,研究了内蒙古典型草原小叶锦鸡儿灌丛化过程对土壤和土壤水文过程的影响,旨在为干旱半干旱区环境保护和恢复提供理论基础。结果表明,斑块尺度上,灌丛斑块土壤有机质和全氮含量分别是草地斑块的1.54倍和1.16倍;灌丛斑块平均沙粒、粉粒和粘粒含量是草地斑块的0.87倍、1.34倍和1.35倍;灌丛斑块土壤容重是草地斑块的0.97倍;灌丛斑块钙积层上表面出现深度是草地斑块的1.27倍。地形等自然条件也是形成土壤异质性的重要因子,坡面尺度上,灌丛和草地斑块土壤有机质、全氮、土壤容重、土壤钙积层上表面出现深度呈自坡顶向坡下方向增加的趋势。染色示踪实验表明,灌丛斑块土壤剖面湿润锋和土壤水分入渗速率分别是草地斑块的1.36倍和5.16倍,草地斑块0~10cm土层对水分的响应较敏感,而灌丛斑块25 cm以下土层对水分的响应较敏感。研究认为,灌丛化过程增强了土壤空间异质性,灌丛斑块能将土壤水分快速输送并存储于深层土壤中,灌丛斑块是土壤养分和水分富集区,灌木植物的定居和发展过程与土壤形态之间形成了正反馈。 相似文献
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