Temporal changes on soil conservation services in large basins across the world

Abstract

Soil erosion is one of the main drivers of land degradation across the world, thus soil conservation service has received increasing attention. Limited studies have focused on it, hence this study investigates spatial and temporal patterns on soil conservation service in four large representative basins globally (i.e., Amazon, Mississippi, Yangtze, and Yellow River Basins), between 2001 and 2018. Annual soil conservation service and soil erosion rate are estimated under RUSLE framework, and temporal trends are analyzed using Mann-Kendall test. Additionally, impacts of soil erosion factors on spatial distribution of soil conservation service are assessed through fitting stepwise regressions annually and calculating the factors’ contributions. Furthermore, driving factors of temporal changes are identified as climate or land cover dominated, and combined effect of both, according to Z scores from Mann-Kendall test for soil conservation service, R and C factors. Results show the Yangtze River Basin produces the highest average annual erosion rate (mean values of 133.28 Mg ha−1 yr−1 in 2001 and 143.21 Mg ha−1 yr−1 in 2018) and average soil conservation service (mean values of 2663.57 Mg ha−1 yr−1 in 2001 and 3126.43 Mg ha−1 yr−1 in 2018). Amazon River Basin yields the lowest average annual soil erosion rate (15.96 Mg ha−1 yr−1 in 2001 and 21.30 Mg ha−1 yr−1 in 2018), whereas the Mississippi River Basin produces the lowest average soil conservation service (388.48 Mg ha−1 yr−1 in 2001 and 730.70 Mg ha−1 yr−1 in 2018). Over the study period, soil conservation service shows an increasing trend in the Yangtze and Yellow River Basins, with average changing rates of 27.23 Mg ha−1 yr−1 and 16.60 Mg ha−1 yr−1, respectively. Increasing soil conservation service is mainly driven by climate change (i.e., rainfall) and the combined effect of climate and land cover changes, but terrain conditions are the main spatial drivers.