Climate regulates the effects of abrupt vegetation shifts on soil
moisture on the Loess Plateau, China
Abstract
Abrupt vegetation shifts indicate sudden and profound changes in
ecosystem structure and function, which may lead to excessive pressures
on regional water resources and thus undermine sustainability. In the
context of ecological restoration and climate change, it is unclear
whether large-scale abrupt vegetation shifts have occurred on the Loess
Plateau and what are the differences and mechanisms associated with the
effects of these vegetation changes on soil moisture content (SMC). In
this study, we found that approximately 27.9% of grasslands and 24.8%
of forests on the Loess Plateau experienced positive abrupt vegetation
shifts from 2000 to 2020, which may be associated with the
implementation of the Grassland Ecological Compensation Program (GECP)
and the Natural Forest Conservation Program (NFCP). By using the climate
zone method and multi-period difference-in-differences (MDID) model, we
found that the effects of abrupt vegetation shifts on SMC were heavily
dependent on local climate conditions. While most abrupt vegetation
shifts could wet surface soil (0–7 cm), only 55.9% of grasslands and
33.9% of forests in abrupt shifts had positive effects on entire soil
(0–289 cm), specifically in areas with lower precipitation and stronger
evaporation conditions. In contrast, approximately 35.7% of grasslands
and 37.6% of forests in abrupt shifts may exacerbate soil drying. This
study fills the knowledge gap in the effects of abrupt vegetation shifts
on SMC and tries to explore the underlying mechanisms, with implications
for water management and ecological programs in areas with similar
climate conditions.