5. CONCLUSIONS
This paper conducted hly soil moisture monitoring of the plant growth season on the CLP and found that the constraint of the minimum accumulated rainfall amount stimulated the surface soil moisture response. A minimum rainfall amount of 5 mm was required to trigger a soil moisture response at a depth of 10 cm at the shrub site, while the other sites demanded ~6 mm. With a larger rainfall amount and higher intensity, rainwater can infiltrate deeper and faster along the 1-m soil profile. Across all the land-cover types, revegetation sites, especially forest and grass, had a deeper response depth, shorter response time, faster response velocity, higher rainfall transformation rate and higher soil water storage of all the rainfall processes in the 1-m profile. These results suggested that rainfall patterns, land-cover types, and their interplays together determined the soil moisture response process. Moreover, after 20 years of vegetation reconstruction, land-cover change can regulate the rainfall-soil moisture response relationship (soil moisture response depth, time, and velocity) and promote rainfall resource utilization efficiency (rainfall transformation rate and soil water storage), which does not aggravate the soil water deficit across the 1-m profile over the rainy season. Therefore, while considering the joint effect of precipitation and land-cover change on soil moisture and soil water storage, abandoned grass may be the best choice for sustainable plant–soil water utilization when the rainfall amount is less than 550 mm, while planted forest, instead of shrub, is beneficial for rainfall utilization and ecosystem water conservation if precipitation is greater than 550 mm.