Abstract
Over the past several decades, vegetation restoration has been carried out extensively in South China. Theoretically, the process of vegetation restoration is usually accompanied by changes in soil properties. However, the effects of vegetation restoration on soil hydraulic properties are poorly documented in humid subtropical China. In this study, we compared soil hydraulic properties across three undisturbed subtropical forests, i.e., Pinus massoniana forest (PF), mixed Pinus massoniana/broad-leaved forest (MF), and monsoon evergreen broad-leaved forest (BF), which represented a vegetation restoration sequence in South China. Our results showed that vegetation restoration decreased the bulk density while increasing the total porosity and the soil organic matter (SOM). The clay content and capillary porosity of soil in the middle- and late-recovery-stage forests were significantly higher than those in the early stage, which was consistent with the soil water-holding capacity. The saturated hydraulic conductivity (KS) values of BF were always significantly higher than those of the other forests. In the whole soil profile, the water-holding capacity and KS in the topsoil (above 30 cm depth) were significantly higher than those in the deep soil for all forests. Further analyses indicated that the SOM was the main factor that affected KS, and the relationship of them could be fitted by a linear equation. Overall, our study revealed vegetation restoration ameliorates soil hydraulic properties in humid subtropical China. And the role of SOM in improving soil hydraulic properties should be emphasized in future forest ecosystem management.
Highlights
Water is the key component of terrestrial ecosystems, and forests serve as a natural reservoir [1,2].Studies have confirmed that the soil layer, as the main aquifer of forest ecosystems, plays an important role in the regulation of water movement in mountainous areas [3,4]
Differences in the Soil Physicochemical Properties of the Three Forests restoration with values ranging from 29.9 g/kg to 54.8 g/kg
Density across the 0–90 cm depth, the soil organic matter (SOM) content was ranked as broadleaf forest (BF) (25.3 g/kg) > massoniana/broad-leaved forest (MF) (16.0 g/kg) > Pinus massoniana forest (PF)
Summary
Studies have confirmed that the soil layer, as the main aquifer of forest ecosystems, plays an important role in the regulation of water movement in mountainous areas [3,4]. Soil hydraulic properties such as saturated hydraulic conductivity and soil water retention characteristics affect runoff generation, the patterns of infiltration, and water retention, etc. Soil physicochemical properties (e.g., soil texture, bulk density, organic matter content) are the basis for the formation of soil hydraulic characteristics [5,6]. The dominant factors affecting soil hydraulic characteristics could differ vastly among different regions.
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