Variations in soil properties and vegetation distribution on short gentle slopes in an arid alluvial gravel desert, Northwest China

Background and aims

Topography-induced changes in soil properties significantly influence vegetation distribution in desert ecosystems. While gravel deserts are generally flat, short gentle slopes are common. However, the effects of these slopes on soil properties and vegetation distribution under arid conditions remain unclear.

Methods

Utilizing field surveys and UAV technology, this study investigated the effects of short gentle slopes positions and depths on soil properties and vegetation distribution in the Linze gravel desert, Northwest China.

Results

Soil properties varied with both slope position and depth, even on slope less than 2°. The 0–10 cm soil layer showed greater variability than the 10–20 cm layer. At the 0–10 cm layer, the lower slope position had significantly higher saturated hydraulic conductivity (Ks) but lower silt, gravel content, and soil water repellency compared to the upper and middle positions (P < 0.05). The mean Ks across all slope positions was relatively low, averaging only 0.39 mm min⁻¹. Considering gravel content significantly improved Ks prediction accuracy (P < 0.05). Variations in surface Ks were key to vegetation distribution. Vegetation distribution exhibited a significant downslope orientation pattern, with lower slopes having 2.2 to 3.7 times more coverage than middle and upper slopes (P < 0.001).

Conclusions

Limited infiltration capacity in gravel deserts led to the redistribution of precipitation across slope positions, even on short gentle slopes, resulting in distinct variation patterns. These findings suggest that lower slope positions are more favorable for native vegetation restoration, offering insights for managing gravel desert ecosystems.

Graphical abstract