Anthropogenic revegetation is an effective way to control soil erosion and restore degraded ecosystems in China's northwest drylands(NWD).However,excessive vegetation cover expansion has long been known to increas...
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Anthropogenic revegetation is an effective way to control soil erosion and restore degraded ecosystems in China's northwest drylands(NWD).However,excessive vegetation cover expansion has long been known to increase evapotranspiration,leading to reduced local water availability,which can in turn threaten the health and services of restored *** the optimal vegetation coverage(OVC)is critical for balancing the trade-off between plant growth and water consumption in water-stressed areas,yet quantitative assessments over the entire NWD are still *** this study,a modified Biome BioGeochemical Cycles(Biome-BGC)model was used to simulate the long-term(1961–2020)dynamics of actual evapotranspiration(ET_(a)),net primary productivity(NPP),and leaf area index(LAI)for the dominant non-native tree(*** and ***)and shrub(*** and ***)species at 246 meteorological sites over *** modified model incorporated the Richards equation to simulate transient unsaturated water flow in a multilayer soil module,and both soil and eco-physiological parameters required by the model were validated using field-observed ETadata for each *** distributions of OVC(given by the mean maximum LAI,LAI_(max))for the dominant species were determined within three hydrogeomorphic sub-areas(i.e.,the loess hilly-gully sub-area,the windy and sandy sub-area,and the desert sub-area).The modified Biome-BGC model performed well in terms of simulating ET_(a) dynamics for the four plant *** distributions of mean ET_a,NPP,and LAI_(max)generally exhibited patterns similar to mean annual precipitation(MAP).In the loess hilly-gully sub-area(MAP:210 to 710 mm),the OVC respectively ranged from 1.7 to 2.9 and 0.8 to 2.9 for *** and *** the windy and sandy sub-area(MAP:135 to 500 mm),the OVC ranged from 0.3 to 3.3,0.5 to 2.6 and 0.6 to 2.1for ***,*** and ***,*** the desert sub-
Soil erosion has been a widely studied hydrological issue, and the further deterioration of soil and water environments caused by soil erosion has attracted extensive attention from global scholars. At present, there ...
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Soil erosion has been a widely studied hydrological issue, and the further deterioration of soil and water environments caused by soil erosion has attracted extensive attention from global scholars. At present, there are relatively few studies on preventing and controlling soil erosion to avoid the introduction of pollutants from surface runoff in grasslands during rainfall events. To identify the optimal vegetation coverage of Cynodon dactylon grassland for controlling soil erosion during rainfall events, bare land (0%) was used as the control in this experiment. Simulated rainfall experiments were carried out with three levels of coverage (30%, 60% and 90%) under four slope conditions (0 degrees, 5 degrees, 10 degrees and 20 degrees) and four rainfall intensities (20 mm/h, 30 mm/h, 60 mm/h and 90 mm/h). The results suggested that the capacity of Cynodon dactylon grassland to reduce the runoff coefficient and sediment yield decreased with increasing rainfall intensity and slope but increased with increasing vegetationcoverage. The results of the structural equation model revealed close relationships between vegetationcoverage and the reduction rate of the runoff coefficient and the reduction rate of the sediment yield. The results of the response surface methodology suggested that the vegetationcoverage of Cynodon dactylon grassland should be higher than 86% to ensure that the reduction rate of the runoff and sediment of grassland is greater than 60%, and it is advisable that the planting slope of grassland not exceed 10 degrees. The results of this study serve as a guide for the recovery and restoration of grasslands to control soil erosion and prevent the production as well as further spreading of pollutants in China. This study highlights the need to consider the prevention and control of soil erosion as a source of pollutants. (C) 2019 Elsevier Ltd. All rights reserved.
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