民乐县土壤保持功能时空演变及影响因素研究

Temporal and spatial evolution of soil conservation function and its influencing factors in Minle County

摘要:

【目的】民乐县是祁连山生态保护区的重要组成部分，探究该区域内土壤保持功能时空变化及影响因素对认识和保护区域内生态系统安全具有重要意义。【方法】基于 InVEST 模型评估民乐县 2000-2020 年土壤保持功能时空动态变化及分布特征，运用机器学习的随机森林算法探究不同土地利用类型的土壤保持能力与自然因素的响应关系。【结果】①民乐县 2000、2010 和 2020 年的土壤保持量分别为 7. 94×10⁷ 、8. 3×10⁷ 和 9. 02×10⁷ t，区域内土壤保持量的空间分布特征为“北部低-南部高”， 在 6 类土地利用类型中土壤保持量最多的是林地，分布范围大且植被覆盖率高，15°~＜25°坡度区间内的土壤保持量最高，海拔为 2 500~＜3 500 m 的祁连山中段区域土壤保持功能最好；②不同利用类型土地的土壤保持功能对影响因素的敏感程度不同，主要影响因素为 Slope、Temp、RX1day、RS、Pre、 TNn 和 RX5day，其中建设用地类型中土壤保持功能变化与坡度变化呈负相关。【结论】民乐县土壤保持功能呈现出逐年增加趋势，各土地利用类型的土壤保持功能与自然气候因素有较强的响应关系，使土壤保持功能出现差异化分布。

Abstract:

【Objective】 Minle County is an important part of the Qilian Mountains Ecological Reserve，therefore， it is important to investigate the spatial and temporal changes of soil conservation function in the region and the influ‐ encing factors in order to understand and protect the security of ecosystem in the region.【Method】 The study as‐ sessed the spatial and temporal dynamics and distribution characteristics of soil conservation function in Minle County from 2000 to 2020 based on the InVEST model. A machine learning Random Forest algorithm was used to explore the response of soil conservation capacity of different types of land use to natural factors.【Result】 The results showed that：① Soil retention in Minle County was 7. 94×10⁷ t，8. 3×10⁷ t and 9. 02×10⁷ t in 2000，2010 and 2020， respectively. The spatial distribution of soil retention in the region was characterized by "low in the north and high in the south". Among the six types of land use，the most abundant soil retention was in forest land，which had a large dis‐ tribution and high vegetation coverage. The highest soil retention was 15°~＜25° slope interval，and the best soil re‐ tention function was found in the middle region of the Qilian Mountains in the elevation range of 2 500~＜3 500m. ② The sensitivity of soil conservation function on different land use types to the influencing factors was different. The main influencing factors were Slope，Temp，RX1day，RS，Pre，TNn and RX5day，among which the change of soil con‐ servation function on construction land types was negatively correlated with the change of slope.【Conclusion】 Soil conservation function in Minle County showed a trend of increasing with each passing year，and the soil conservation function of each land use type had a strong responsive relationship with natural climatic factors，attributing to the dif‐ ferential distribution of soil conservation function.