Wang Ting, Xu Qing, Gao Deqiang, Zhang Beibei, Zuo Haijun, Jiang Jing
Key Laboratory of Forest Ecology and Environment of National Forestry and Grassland Administration, Research Institute of Forest Ecology, Environment and Protection, Chinese Academy of Forestry, Beijing, 100091, China.
University of Calgary, Calgary, T2N1N4, Canada.
Sci Rep. 2021 Jun 22;11(1):13029. doi: 10.1038/s41598-021-92423-5.
Forest management practices play an important role in regulating the soil water-holding capacity of plantation. However, most studies focus on soil water dynamics present during large-scale forest loss and afforestation events, while little is known about how soil water under different forest management practices responds to rainfall events and which factors mainly regulate soil water-holding capacity. In this study, a stable hydrogen isotope was used to explore the contribution of three natural rainfall events (8.9, 13.3 and 67.7 mm) to soil water (CRSW) in a Pinus massoniana plantation under four forest management practices (no thinning (NTN), understory removal (USR), light-intensity thinning (LIT) and heavy-intensity thinning (HIT)) in the Three Gorges Reservoir Area of the Yangtze River Basin in China. Furthermore, a structural equation model was employed to determine the effects of vegetation biomass and soil properties on the CRSW. The results showed that plantation soil under different forest management practices exhibited different water-holding capacities. Following light (8.9 mm) and moderate (13.3 mm) rainfall events, the CRSW in the HIT stand was slightly higher than that in the other stands. Following heavy (66.7 mm) rainfall event, the CRSW of most layers in USR stand was not different from the other three stands, while the CRSW in the LIT and NTN stands was significantly higher than that in the HIT stand in the 0-100 cm soil layers, suggesting that soil in the LIT and NTN stands had a greater water-holding capacity than that in the HIT stand. In addition, soil properties were the main factors directly affecting the CRSW, explaining 60% and 37% of the variation in the CRSW on the first and seventh days after heavy rainfall, respectively. Overall, compared to the HIT stand, the LIT and NTN stands showed greater capacity in retaining rainwater. Therefore, under expected global changes with frequent occurrences of extreme precipitation events, methods involving light-intensity and no thinning should be employed to build up soil and water conservation functions, which will be critical for keeping water-holding capacity and moderating floods.
森林经营措施在调节人工林土壤持水能力方面发挥着重要作用。然而，大多数研究集中在大规模森林砍伐和造林事件期间的土壤水分动态，而对于不同森林经营措施下的土壤水分如何响应降雨事件以及哪些因素主要调节土壤持水能力却知之甚少。在本研究中，利用稳定氢同位素探究了长江流域三峡库区马尾松人工林在四种森林经营措施（未间伐（NTN）、除灌（USR）、轻度间伐（LIT）和重度间伐（HIT））下，三次自然降雨事件（8.9、13.3和67.7毫米）对土壤水分（CRSW）的贡献。此外，采用结构方程模型确定植被生物量和土壤性质对CRSW的影响。结果表明，不同森林经营措施下的人工林土壤表现出不同的持水能力。在小雨（8.9毫米）和中雨（13.3毫米）事件后，HIT林分的CRSW略高于其他林分。在大雨（66.7毫米）事件后，USR林分大多数土层的CRSW与其他三个林分无差异，而在0-100厘米土层中，LIT和NTN林分的CRSW显著高于HIT林分，这表明LIT和NTN林分的土壤持水能力大于HIT林分。此外，土壤性质是直接影响CRSW的主要因素，分别解释了大雨后第一天和第七天CRSW变化的60%和37%。总体而言，与HIT林分相比，LIT和NTN林分在截留雨水方面表现出更强的能力。因此，在预计全球变化导致极端降水事件频繁发生的情况下，应采用轻度间伐和未间伐的方法来增强水土保持功能，这对于保持持水能力和缓解洪水至关重要。
