Land cover changes the soil moisture response to rainfall on the
Loess Plateau
Fengchi Ge a,
Mingxiang Xu a,
b, c, *, Chen Gong b, c, Zuoyuan Zhangd, Qingyue Tan e,
a College of Forestry, Northwest A&F University,
Yangling 712100, China
b Institute of Soil and Water Conservation, Northwest
A&F University, Yangling 712100, China
c State Key Laboratory of Soil Erosion and Dryland
Farming on the Loess Plateau, Institute of Soil and Water Conservation,
Chinese Academy of Sciences and Ministry of Water Resources, Yangling
712100, China
d Institute of Soil and Water Conservation, Northwest
A&F University, Yangling 712100, China
e College of Forestry, Northwest A&F University,
Yangling 712100, China
Corresponding Author: Mingxiang Xu, Institute of Soil and Water
Conservation, Northwest A&F University, Yangling 712100, China.
Email: xumx@nwsuaf.edu.cn
Abstract: Insight into the rainfall-soil moisture (SM) response
to land cover is critical for soil hydrological process modeling and
management. In this study, five typical land-cover types (forest, shrub,
grass, crop, and bare land) and four rainfall patterns (heavy,
intermediate, light, and continuous rains) were selected to assess the
effects of SM response characteristics on the Loess Plateau of China. We
monitored SM at five depths on each land-cover type at 1-h intervals
over the growing season of 2019. The results showed that rainfall
patterns and land-cover typestogether determined the SM response process
and infiltration efficiency. A minimum accumulated rainfall amount of 5
mm was the threshold to trigger a 10-cm SM response. Rain events with
higher intensity and smaller sum triggered a quick surface SM response,
while larger amounts could percolate deeper and faster. Land-cover
change significantly altered the rainfall-SM response dynamics and
rainwater utilization efficiency after 20 years of ecological
construction. Revegetation sites (mean values of forest, shrub, and
grass) increased the soil wetting depth by 14.7%, shortened the SM
response time by 27.3%, and accelerated the SM wetting front velocity
by 67.2%, which promoted a 35.2% rainfall transformation rate (RTR)
across the 1-m profile over all rainfall events (R1-13).
Moreover, planted forest showed the highest RTR of R1-13and the maximal increase in soil water storage, which did not aggravate
the soil water deficit across the 1-m profile over the growing season.
Therefore, we present evidence that planted forests, instead of shrubs,
may be beneficial for water conservation if precipitation is greater
than 550 mm. The findings of this study prove the role of revegetation
on rainwater infiltration capacity and efficiency and can help improve
the management of afforestation in arid and semiarid regions.
Keywords: soil moisture response; land cover; rainfall;
revegetation; soil water storage; Loess Plateau