Soil erosion is a critical contributor resulting in land degradation and the decline of ecosystem services at the global scale. Land use/cover change may alter some key soil physico-chemical properties, such as the organic carbon (C) content and mean weight diameter of aggregates (MWD), which will greatly affect splash erosion. However, few studies have addressed the effects of changes to inherent soil properties (e.g., soil compaction, aggregate stability and size distribution) on splash erosion.
In a study published in Geoderma, researchers from Xishuangbanna Tropical Botanical Garden (XTBG) tried to estimate the potential response of soil aggregates of different particle sizes to splash erosion under natural rainfall conditions by comparing two land-use regimes, primary tropical rainforest (TR) and managed rubber plantation (RP) in Xishuangbanna.
The researchers exposed splash cups containing dry-sieved aggregate samples with eight size classes to natural rainfall to measure the splash erosion rate. The results showed that the average splash erosion at aggregate scale in rubber plantation was 10% higher than that in tropical rainforest.
The organic carbon (C) and nitrogen (N) within bulk soil, as well as individual aggregate fractions, were found obviously higher in tropical rainforest than in rubber plantation, suggesting that forest conversion and accompanying management practices had significantly negative effects on the C and N stocks. Some key soil properties (e.g., hydraulic conductivity) varied with the conversion of tropical rainforest into rubber plantation.
They further found that long-term rubber cultivation with intensive management practices (e.g., terrace building and regular latex tapping) resulted in soil degradation, C and N loss and a decline in aggregates stability. “These negative changes in soil structure and properties made soil susceptible to splash erosion, posing a major threat to the sustainability of rubber plantation ecosystems,” said ZHU Xiai of XTBG.
Moreover, they found that various rainfall parameters (e.g., kinetic energy, rainfall amount and maximum intensity) had significantly positive effects on splash erosion rates.
“Our study highlights the validation of soil disaggregation characterization as a proper indicator of aggregate susceptibility to rain splash erosion under land-use change,” said LIU Wenjie of XTBG.
LIU Wenjie Ph.D Principal Investigator
Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan 666303, China