Landslide-impacted soils recover faster biologically than chemically or physically, though recovery also varies with forest type in subtropical China

Understanding how natural disasters affect soil quality and how it recovers is essential to improve soil man-agement. We studied the effects of the 2010 Nanping landslides (China) on soil quality. We conducted an observational study using three levels of disturbance ('destroyed', 'recovering', and 'undisturbed'). The 'destroyed' areas were sampled immediately after the landslide and the others were sampled 7 years later. To assess the consistency of landslide-induced effects, we sampled these levels of disturbance in three forest types (Cunninghamia lanceolata conifer forest, Phyllostachys heterocycla bamboo forest, and secondary evergreen broadleaf forest). In total, 81 soil samples were collected and analyzed for 26 soil indicators. A minimum data set (MDS) was identified that represented the physical, chemical, and biological properties of the soils. Indicators in the MDS were then weighted and summed together to calculate a soil quality index (SQI) for each category and a total SQI. The landslide strongly affected all aspects of soil quality. After seven years of natural recovery, most aspects of soil quality were significantly improved but remained lower than in 'undisturbed' sites. Recovery was faster for biological than physical or chemical properties. Recovery was slower in bamboo forests than in other forest types, suggesting that human interventions could accelerate post-landslide soil recovery in bamboo forest. Our results provide fundamental data for evaluating impacts of natural disasters on soil and rates of natural recovery.