Correspondence analysis between vegetation cover and sheet erosion rate on an abandoned farmland slope based on 7Be measurement

Abstract

Scale effects, the phenomena of runoff and sediment yield differ from different spatial and temporal scales, exist in the whole process of soil erosion. Vegetation cover can reduce the degree of soil erosion at the plot and slope scales, but there is little research on the reduction effect of vegetation on soil erosion at a specific point on the plot, due to the limitations of traditional methods. Based on in situ sampling on a representatively abandoned farmland slope, the corresponding relationship between vegetation and sheet erosion was analyzed quantitatively using the modified 7Be tracing model with vegetation factor. The results showed that 7Be activity per unit mass and per unit area in soil ranged from 2.45 to 27.05 Bq kg−1 and 50.09 to 528.11 Bq m−2, and in plants ranged from 378.20 to 691.82 Bq kg−1 and 72.61 to 307.33 Bq m−2, respectively. Plants were responsible for 22.6 %±7.3 % of total 7Be interception on the slope, affected by vegetation coverage, leaf area index, dry biomass and flesh weight. Plants were mainly distributed on the backslope and toeslope, with vegetation coverage, leaf area index, dry biomass and flesh weight ranging from 0.26 to 0.75, 0.48 to 2.45, 0.17 to 0.45 kg m−2 and 0.38 to 0.85 kg m−2, respectively, while the peak area of soil erosion was concentrated on the backslope, with a rate ranging from 0.06 to 16.76 kg m−2. At the specific point scale, the corresponding relationships between soil erosion and vegetation coverage, leaf area index, dry biomass, and flesh weight of plants are not as significant as in the previous study at the plot or slope scale. This indicates that the reduction of erosion for plants varies with scale dependency, which is more complicated at the specific point scale, rather than simply decreasing with the increase of vegetation. Our results highlight that there is a scale effect of plants on soil erosion, and the 7Be measurement is of great potential to explore this effect at the specific point scale.