甘南黄河上游植被覆盖度时空变化与地形因子的关系

Vegetation cover in the Upper Yellow River in Gannan plays an important role in maintaining the structural stability of the alpine ecosystem and conserving water sources. Exploring the spatiotemporal variation of vegetation cover and its relationship with topographic factors and characterizing the spatiotemporal distribution of vegetation can deepen our understanding of the dynamics and functions of the alpine vegetation ecosystem and provide theoretical support for maintaining ecological balance and restoring vegetation. Based on Landsat images and Digital Elevation Model data for 19902020 at the Upper Yellow River in Gannan, this study used a pixel dichotomous model, one-dimensional linear regression equation, superposition analysis, geographic detector, and other methods to intensively study the spatiotemporal changes of vegetation coverage and the correlation of topographic features in the study area. The results showed the following: (1) From 1990 to 2020, the vegetation coverage in the Upper Yellow River in Gannan experienced a transition from degradation to recovery and then to significant improvement. The area with medium and high vegetation coverage (0.60.8) constituted the largest proportion, accounting for 77.68% of the total study area. (2) Between 1990 and 2020, the vegetation coverage in the study area showed a significant improvement trend. Among them, the area where vegetation coverage improved (Slope > 0) accounted for approximately 91.26% of the total area, which was much larger than the area where it declined (Slope < 0). (3) There were significant differences in the explanatory power of the topographic factors on the FVC. Elevation is the main factor driving FVC, and the explanatory power of the interaction of topographic factors such as slope, slope direction, and elevation is greater than that of a single factor. (4) Vegetation cover in the study area showed a single-peak pattern of increasing and then decreasing with both elevation and slope; the highest vegetation cover was found on southerly slopes, while the lowest was on northeasterly slopes. In the time series, the area of vegetation coverage from the north to the southwest shows a shrinking trend, while the areas in the southwest, west and northwest directions are increasing. The results of this study can provide scientific support for ecological protection and high-quality development in the Upper Yellow River in Gannan.