评估放牧干扰对天山北坡土壤侵蚀及空间特征的影响

Assessment on the Impact of Grazing Disturbance on Spatial Characteristics of Soil Erosion on the Northern Slope of Tianshan Mountains

为定量研究天山北坡牧场放牧干扰对土壤侵蚀的影响,基于Biome-BGC模型及落叶方程模拟放牧干扰前后生物量,采用"生物量—植被覆盖度"模型估算生物措施因子,结合中国土壤流失方程探索构建放牧干扰对土壤侵蚀定量评估模型,空间显式表达2019年天山北坡牧场放牧干扰前后土壤侵蚀空间特征及对土壤侵蚀影响的程度。结果表明:(1) 2019年天山北坡牧场平均放牧强度为8.11羊/hm^(2);其中昌吉市(12.24羊/hm^(2))最高,玛纳斯县(1.87羊/hm^(2))最低。(2)天山北坡放牧干扰前后的土壤侵蚀空间特征,在季节牧场一致,均呈现夏牧场>冬牧场>春秋牧场格局,在县域发生改变但变幅较小。(3)放牧干扰引起的天山北坡土壤侵蚀模数增幅在季节牧场为春秋牧场20.65%>夏牧场15.57%>冬牧场15.46%;县域为沙湾县31.93%>阜康市24.24%>达坂城区22.04%>乌鲁木齐县7.56%>玛纳斯县5.34%>昌吉市5.30%>呼图壁县4.37%。放牧干扰是春秋牧场及沙湾县土壤侵蚀的主要原因,自然条件是夏牧场、冬牧场及乌鲁木齐县、昌吉市土壤侵蚀主要原因。研究可为定量表征放牧干扰对土壤侵蚀的影响提供参考,对天山北坡牧区水土保持工作提供一定的科学依据。

To quantitatively study the impact of grazing disturbance on soil erosion on the northern slope of Tianshan Mountain, the biomass before and after grazing disturbance was simulated based on the Biome-BGC model and the defoliation formulation. The ‘biomass-vegetation coverage’ model was used to estimate biological measure factors. The Chinese soil loss equation was employed to explore the construction of a quantitative assessment model of grazing disturbance on soil erosion, the spatial characteristics of soil erosion before and after grazing disturbance on the northern slope of Tianshan Mountains in 2019 and the degree of impact on soil erosion were spatially and explicitly expressed. The results show that:(1) the average grazing intensity of the pastures on the northern slope of Tianshan Mountain in 2019 was 8.11 sheep/hm^(2), the highest was found in Changji City(12.24 sheep/hm^(2)), and the lowest was found in Manas County(1.87 sheep/hm^(2));(2) the spatial characteristics of soil erosion before and after grazing disturbance on the pastures on the northern slope of Tianshan Mountains were consistent on seasonal pastures, and the order was summer pasture>winter pasture>spring and autumn pasture;(3) soil erosion modulus on the northern slope of Tianshan Mountain decreased in the order: 20.65% in spring and autumn pastures>15.57% in summer pastures>15.46% in winter pastures on seasonal pastures, and 31.93% in Shawan County>24.24% in Fukang City>Daban City 22.04%>Urumqi County 7.56%>Manas County 5.34%>Changji City 5.30%>Hutubi County 4.37%. Grazing disturbance is the main influencing factor of soil erosion in spring and autumn pastures in the study area and all pastures in Shawan County. Natural conditions are the main influencing factors of soil erosion in summer and winter pastures in the study area and all pastures in Urumqi County and Changji City. This research can provide the reference for quantitatively characterizing the influence of grazing disturbance on soil erosion, and provide a certain scientific basis for soil and water conservation in the grazing area of the northern slope of Tianshan Mountains.