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.