Humid karst ecosystems are fragile, with precipitation being the main source of soil moist ure recharge. The process of soil moisture recharge and usage varies by vegetation type. To analyze the dynamics of soil moisture under different vegetation types during rainfall events, we continuousl y monitored soil moisture in arable land, grassland, shrub, and forest areas at 10-minute intervals fro m November 6, 2019, to January 6, 2020.The arable land was used as a control group. Soil moistur e under the different vegetation types responded to light, moderate, and rainstorm events with large r ainfall amounts. However, only the soil moisture in the grassland areas responded to a light rainfall event with a rainfall amount of 0.87 mm. The largest soil moisture recharge (12.63 mm) and decline (2.08%) were observed for the grassland areas, with the smallest observed for the forest areas. Whi le the grassland areas showed the greatest decline in soil moisture following rainfall, they were mor e easily recharged during the winter rainfall events. Soil moisture in forests and shrubs was less rec harged than in grasslands but also declined less. Therefore, forests and shrubs are better at retaining soil moisture in winter, which is informative for the formulation of a regional vegetation recovery m odel.

Humid karst ecosystems are fragile, with precipitation being the main source of soil moisture recharge. The process of soil moisture recharge and usage varies by vegetation type. To analyze the dynamics of soil moisture under different vegetation types during rainfall events, we continuously monitored soil moisture in arable land, grassland, shrub, and forest areas at 10-minute intervals from November 6, 2019, to January 6, 2020.The arable land was used as a control group. Soil moisture under the different vegetation types responded to light, moderate, and rainstorm events with large rainfall amounts. However, only the soil moisture in the grassland areas responded to a light rainfall event with a rainfall amount of 0.87 mm. The largest soil moisture recharge (12.63 mm) and decline (2.08%) were observed for the grassland areas, with the smallest observed for the forest areas. While the grassland areas showed the greatest decline in soil moisture following rainfall, they were more easily recharged during the winter rainfall events. Soil moisture in forests and shrubs was less recharged than in grasslands but also declined less. Therefore, forests and shrubs are better at retaining soil moisture in winter, which is informative for the formulation of a regional vegetation recovery model.

Understanding the response of soil moisture of different vegetation types to rainfall in karst regions in winter is significant for implementing various ecological restoration projects. However, at present, the related research is mainly focused on non-winter seasons, and only few research exist on winter seasons. Therefore, in this study, four types of vegetation – grassland, arable land, shrubland, and forestland – were selected as sample plots in the Guanling County of southwestern Guizhou, China. The magnitude, time, and speed responses of soil moisture of the vegetation types to rainfall were calculated using the time-series data of soil moisture of different vegetation types. The results showed that the response of soil moisture differed between different vegetation types in winter and non-winter seasons in karst areas. Among the four vegetation types, soil moisture response magnitude to rainfall in grassland and arable land had a similar distribution pattern along different soil depths, whereas, in scrubland and forestland, it decreased gradually along the soil depth. In addition, compared with other vegetation types, for grassland soil moisture, the response magnitude, response duration, and response speed to rainfall are the largest, longest, and fastest, respectively. Our study used quantitative indices to illustrate the response of soil moisture to rainfall for different vegetation types under a humid climate in a mid-subtropical zone on sloped, pure limestone land. The results of this study provide a scientific basis for the implementation of ecological restoration projects in karst areas.

Socioeconomic factors are important parameters that affect vegetation changes in karst areas. Previous studies primarily focused on ecological engineering when analyzing the impact of human activities on vegetation restoration, whereas the impact of socioeconomic factors has been less studied. Using the methods of structural equation modeling and geographically weighted regression, this study quantitatively analyzed the interactive effects of socioeconomic factors on vegetation changes in karst areas using counties as the research unit. The results showed that both the enhanced vegetation index and net primary productivity in the humid karst areas of China showed an increasing trend between 2000 and 2020. Among the socioeconomic factors, non-agricultural economy and rural economy had a positive effect on vegetation change, with maximum path coefficients of the structural equation model of 0.79 and 0.64, respectively; whereas population pressure had a negative impact with a minimum path coefficient of –0.80. Over time, the positive impact of rural economy on vegetation restoration showed an increasing trend, and the path coefficient increased from –0.92 to 0.64; in turn, non-agricultural economy and population pressure showed a decreasing trend. Moreover, because they were affected by the heterogeneity of the karst mountain environment, the impact of various socioeconomic factors on vegetation restoration had obvious spatial non-stationarity. The results of this study will promote our understanding of the mechanism underlying vegetation change in humid karst areas and provide scientific reference for ensuring the sustainability of the ecological effects in these areas.

Understanding the response process of the soil moisture of different vegetation types to rainfall in karst regions in winter is of great significance to the implementation of various ecological restoration projects. However, at present, the related research is mainly focused on nonwinter seasons, so there is less winter research. Therefore, in this study, in Guanling County, Anshun City, southwestern Guizhou Province, four types of vegetation, grassland, arable land, shrubland, and forestland, were selected as sample plots, and the degree、time and speed responses of the soil moisture of the vegetation types to rainfall were calculated using the time series data of the soil moisture of different vegetation types. The results showed that among the four kinds of vegetation in karst regions in winter, the response degree of the grassland soil moisture to rainfall was largest, response duration was longest, and response speed was fastest. Also, the increment of the soil moisture in the adjacent arable land soil layers significantly changed. In addition, in light rain events, only the soil moisture of the grassland and arable land responded. Overall, in this study, quantitative indices were used to illustrate the response process of soil moisture to rainfall for different vegetation types under the humid climate type of the mid-subtropical zone in pure limestone slope lands, thus enriching relevant knowledge systems and providing more scientific bases for the implementation of ecological restoration projects in karst areas.