Subjects: Geosciences >> Geography submitted time 2024-06-12 Cooperative journals: 《干旱区研究》
Abstract： There are a large number of rodent mounds in the alpine grassland rodent activity area of the Yellow River source, and soil wind erosion is easy to occur under the influence of dry and windy climate. In order to clarify the characteristics and laws of soil wind erosion in rodent mounds, this study took the Ochotona curzoniae and Myospalax baileyi mounds in 14 test areas at different altitudes and vegetation coverage in the Yellow River source basin as the research objects. The field simulated wind erosion test device was used to analyze and discuss the soil loss and nutrient loss law of rodent mounds in different regions under different wind speeds. results showed: (1)There was a significant difference in the amount of soil wind erosion between different regions ( P<0.05 ). When the wind speed is small, there is no significant difference in soil loss between the two different mounds. When the wind speed increased to 12 m·s-1, the soil loss of plateau pika mound was greater than that of plateau zokor mound ( P<0.05 ). When the wind speed increased from 3 m·s-1 to 12 m·s-1, the average increase of soil loss in the two kinds of mounds was 238.16% and 146.31%, respectively. (2) The wind erosion rate of the mound soil in each test area generally showed a decreasing trend from fast to slow. Vegetation coverage was a significant factor affecting the soil loss of the mound under low wind speed and was related to altitude. (3)With the aggravation of grassland degradation, soil total nitrogen content, available nitrogen, available potassium and organic matter content decreased significantly, while total phosphorus, total potassium and available phosphorus showed an upward trend. This study shows that the difference of soil wind erosion in different regions of the Yellow River source is closely related to soil moisture content, particle size and wind speed.
Subjects: Geosciences >> Geography submitted time 2024-03-01 Cooperative journals: 《干旱区研究》
Abstract： Soil shear resistance in the Riparian zone directly affects riverbank stability. Furthermore, theinfluence of freezing and thawing on the structure and mechanical properties of alpine meadow soils is directlyrelated to the collapse frequency and lateral migration of the river bank in the source region of the Yellow River.To investigate the change rules and generation mechanisms of the root bearing soil mass, the shear strength indexin the meandering Riparian zone of the source region of the Yellow River under the effects of freezing andthawing were assessed. The subsequent impacts of different root contents on the soil mass shear strength indexwere also determined using an indoor freeze-thaw direct shear test with remolded soil. The experimental resultsshow that plant roots can significantly and increasingly enhance soil cohesion, which can range from 2.7% to77.9%. Variations in the internal friction angle with root content were not significant. The freeze- thaw cycleweakens soil cohesion, especially in the early stages. The maximum decrease in cohesion of 19.0% occurred withthree freeze- thaw cycles, after which the changes stabilized, while the internal friction angle showed a slightincreasing trend. The effects of the freeze-thaw action on the shear strength index of the rooted soil is smallerthan that of the plain soil. Under the same freeze- thaw frequency conditions, the decrease in cohesion of therooted samples was found to be smaller than that of the plain soil samples. The root systems of meadow plantscan block the changes in soil temperature, reduce the decrease in soil cohesion, and increase with the rootcontent. When the root content reaches 11%, its weakening effect on soil cohesion is 4.2%-27.7% less than thatof plain soil. The Riparian zone, as the source area of the Yellow River, should strengthen the protection ofriverside meadow vegetation, maximize the role of the root system in enhancing Riparian stability, and protectriver ecology.
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