Jixian National Forest Ecosystem Observation and Research Station, CNERN, School of Soil and Water Conservation, Beijing Forestry University, Beijing, 100083, PR China; Key Laboratory of Soil and Water Conservation and Desertification Combating, State Forestry and Grassland Administration, PR China.
Institute for Land and Water Management Research, Federal Agency for Water Management, A-3252, Petzenkirchen, Austria.
Environ Res. 2022 Nov;214(Pt 1):113774. doi: 10.1016/j.envres.2022.113774. Epub 2022 Jun 28.
Vegetation plays a vital role in regulating hydrological cycle and controlling soil erosion at multiple spatial and temporal scales. Establishing shrub-grass community is one of the widely adopted practices to increase rainfall infiltration and reduce soil erosion in water-limited and highland regions. To understand the effects of such vegetation communities on soil erosion and overland flow under different rainfall regimes at the hillslope scale, we conducted rainfall simulation experiments by setting up parallel plots at fixed slope of 15 including unvegetated (coverage 0%), shrub only (coverage 50%), grass only (coverage 50%), and shrub-grass covered (coverages 25%, 50%, 75%, and 100%) and constant rainfall intensities of 30, 60, and 90 mm h rainfalls lasting 60 min each after the initiation of overland flow. Two native species Lespedeza bicolor and Carex giraldiana, distributed in the soil sampling region were planted on the plots to achieve designed coverages. We found that the overland flow and sediment load from vegetated slopes were reduced by 9%-58% and 27%-98%, respectively, compared with unvegetated slopes while the infiltration rate increased by over 45%. Shrub-grass community reduced the overland flow and sediment yield more significantly than shrub only and grass only treatments with the same coverage of 50% under three rainfall intensities. In addition, the overland flow rate linearly decreased while the mean sediment yield exponentially reduced against the increase in shrub-grass community coverage. Hydrodynamically, shrub-grass communities not only increased the critical hydrodynamic forces for the initiating soil erosion but also increased the resistance coefficient leading to reduce overland flow velocity, stream power, and thus soil erosion from the vegetative slope even under extreme rainfalls. Our research highlights the importance of developing the shrub-grass communities to reduce the quantity and energy of overland flow and control soil erosion on the hillslopes in water-limited and highland regions.
植被在多个时空尺度上对水文循环和控制土壤侵蚀起着至关重要的作用。在水分限制和高海拔地区，建立灌草群落是增加降雨入渗和减少土壤侵蚀的广泛采用的方法之一。为了了解这种植被群落对不同降雨条件下坡面尺度土壤侵蚀和坡面流的影响，我们在固定坡度为 15°的坡面上设置了平行样地，开展了降雨模拟实验，样地植被类型有无植被（盖度 0%）、单灌丛（盖度 50%）、单草丛（盖度 50%）、灌草复合（盖度 25%、50%、75%和 100%），恒定雨强分别为 30、60 和 90 mm·h，每个雨强的降雨持续 60 min，当坡面开始产流后就开始降雨。在样地上种植了两种分布在土壤采样区的乡土物种，即胡枝子（Lespedeza bicolor）和薹草（Carex giraldiana），以达到设计的盖度。结果发现，与无植被坡面相比，植被坡面的坡面流和泥沙负荷分别减少了 9%-58%和 27%-98%，而渗透速率增加了 45%以上。在三种雨强下，灌草复合群落（盖度 50%）的坡面流和泥沙产沙量比单灌丛和单草丛处理分别减少了 58%和 98%。此外，随着灌草复合群落盖度的增加，坡面流率呈线性下降，而平均泥沙产沙量呈指数下降。水动力方面，灌草复合群落不仅增加了引发土壤侵蚀的临界水动力力，还增加了阻力系数，从而降低了植被坡面的坡面流速、水流功率，进而减少了土壤侵蚀，即使在极端降雨条件下也是如此。本研究强调了在水分限制和高海拔地区的山坡上发展灌草复合群落以减少坡面产流的数量和能量、控制土壤侵蚀的重要性。
