长江源高寒草地存在不同程度的退化,导致局部水土流失仍呈增加的趋势。为研究高寒草地退化对土壤分离速率的影响,开展不同植被退化程度坡面径流冲刷试验。结果表明,植被完全退化坡面的高山草甸土平均分离速率(0.54 g/(cm2·min))显著大于重度和中度退化坡面(0.34和0.12 g/(cm2·min)),并远大于轻度退化的坡面(0.03 g/(cm2·min));完全退化坡面的淡寒钙土平均分离速率(4.29 g/(cm2·min))分别是寒钙土、草甸沼泽土和高山草甸土的3.25、7.27和7.94倍。不同退化程度的土壤分离速率随水流剪切力、径流功率与过水断面单位能量的增加,均呈较好的线性或幂函数关系,但与水流功率的拟合效果最好。在相同水流功率条件下,长江源土壤分离速率大于西南及黄土高原地区。本研究可为长江源区土壤侵蚀机理的研究和水土保持措施优化配置提供参考。
Abstract
The alpine grassland in the source of the Changjiang River has degraded to different degrees, resulting in an increasing trend of local soil erosion. To study the effect of alpine grassland degradation on soil detachment rate, we conducted runoff scour experiments on slopes with different vegetation degradation degrees. Results show that the average detachment rate of alpine meadow soil on fully degraded slopes is 0.54 g/(cm2·min), significantly higher than those on severely (0.34 g/(cm2·min)) and moderately degraded slopes (0.12 g/(cm2·min)), and much more higher than that on lightly degraded slopes (0.03 g/(cm2·min)). The average detachment rate of lightly frigid calcic soils on fully degraded slopes is 4.29 g/(cm2·min), 3.25, 7.27 and 7.94 times that of frigid calcic soil, meadow swamp soil and alpine meadow soil, respectively. Soil detachment rates on slopes of different degradation degrees have a good linear or power function relationship with the increase of shear force of water flow, runoff power and unit energy of water cross section, but have the best fitting effect with water flow power. Under the same flow power condition, soil detachment rate in the source region of the Changjiang River is higher than those in the southwest and the loess plateau. The findings can provide reference for studying soil erosion mechanism and optimal allocation of soil and water conservation measures in the source region of the Changjiang River.
关键词
长江源 /
高寒草地 /
土壤侵蚀 /
植被退化 /
土壤分离速率
Key words
headwaters of the Changjiang River /
alpine grassland /
soil erosion /
vegetation degradation /
soil detachment rate
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基金
国家自然科学基金项目(42107352,U2240226);raybet体育在线
中央级公益性科研院所基本科研业务费项目(CKSF2021485/TB,CKSF2019292/TB)
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