Will the conversion of evergreen and deciduous broad-leaved mixed
forests to Chinese fir plantations affect the transportation of soil
water?
Abstract
The conversion of natural forests to planted forests has become a global
trend, and the practice has wide-ranging effects on soil. This study
aimed to explore the differences in soil water movement after the
conversion of evergreen and deciduous broad-leaved mixed forests
(natural forest, NF) to Chinese fir (Cunninghamia lanceolate (Lamb.)
Hook.) plantations (CFP, 20–21 years old). Soil samples from five
layers (0–5, 5–10, 10–20, 20–30, and 30–50 cm) were collected from
NF and CFP before and after rainfall event in the Peng Chongjian
watershed, Jiangxi Province. The physical properties of the soils,
including the mean and coefficient of variation (CV) of soil moisture
content and the soil particle composition, were determined in both
forest types. The δD of soil water and the litter water-holding capacity
were also measured. The results showed that the variation ranges of
moisture content in each soil layer after the rainfall was
21.13%–49.40% in CFP and 21.33%–43.87% in NF. There were no
significant differences in soil bulk density or porosity; the clay and
silt contents were significantly increased in topsoil, while the sand
was significantly decreased (P < 0.05). After the rainfall,
soil water in CFP responded more promptly than NF. In the process of
infiltration, the contribution of rainfall to soil moisture gradually
decreased with increasing soil depth. Topsoil (0–5 cm) in NF responded
promptly to rainfall, but the response showed a lag effect with the
increase of soil depth. With the extension of infiltration time, the
contribution of precipitation to deep soil gradually increased. The
results showed that the soil did not degrade after the conversion of NF
to CFP, a significant guiding result for plantation cultivation.