State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China.
State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China; Advanced interdisciplinary Institute of Environment and Ecology, Beijing Normal University, Zhuhai 519087, China.
Sci Total Environ. 2022 Sep 1;837:155897. doi: 10.1016/j.scitotenv.2022.155897. Epub 2022 May 13.
Variations in litter decomposition and nutrient migration are constraints to accurately estimate watershed diffuse forest pollution under the combined effects of topographic heterogeneity and climate change. In this study, remote sensing data, decomposition and leaching experiments, and the Soil and Water Assessment Tool (SWAT) were used to quantify the release, export, and transport characteristics of diffuse nutrients from forest litter under two climate scenarios (the current climate condition [S1] and the future warming and drying climate condition [S2]), and the impacts on aquatic environment were identified. The annual litter decomposition was 27.80 × 10 t in S2, which was 1.39 times that of S1. Additionally, the annual litter nutrient release in S2 (C, N, and P was 8.65 × 10, 3.31 × 10, and 1.57 × 10 t, respectively) also increased by 31.16%-45.62% compared with that of S1. The spatial patterns of nutrient export showed that the annual exports of C, N, and P in S1 were 109.77, 46.85, and 0.43 kg/ha, respectively. The annual nutrient export in S2 increased by 1.44 times, and S2 also had higher values of nutrient transport. In addition, variation trends of temperature and precipitation increased significantly with increasing altitude, which promoted differences in nutrient transport between S1 and S2 in the high-altitude areas. The response analysis of the diffuse nutrient in surface water also indicated that forest nutrient discharge load were critical factors affecting the aquatic environmental quality. This study indicated that climate warming accelerated litter decomposition and made litter a potential source of diffuse forest pollution, and watershed discharge load varied intensively with the terrestrial conditions. The combination of experiments and modeling can improve the accuracy of diffuse forest pollution simulation and provide valuable information for formulating watershed climate change adaptation strategies.
变异性的凋落物分解和养分迁移是准确估计流域分散森林污染的限制因素，这种污染是地形异质性和气候变化综合作用的结果。在这项研究中，使用遥感数据、分解和淋溶实验以及土壤和水评估工具（SWAT），量化了在两种气候情景（当前气候条件[S1]和未来变暖干燥气候条件[S2]）下，森林凋落物中分散养分的释放、输出和输运特征，并确定了对水生环境的影响。在 S2 中，年凋落物分解量为 27.80×10 t，是 S1 的 1.39 倍。此外，S2 中每年的凋落物养分释放量（C、N 和 P 分别为 8.65×10、3.31×10 和 1.57×10 t）也比 S1 增加了 31.16%-45.62%。养分输出的空间格局表明，S1 中 C、N 和 P 的年输出量分别为 109.77、46.85 和 0.43 kg/ha。S2 中每年的养分输出量增加了 1.44 倍，S2 中养分的输运量也更高。此外，温度和降水的变化趋势随海拔的升高而显著增加，这促进了 S1 和 S2 之间在高海拔地区养分输运的差异。地表水中的弥散养分响应分析也表明，森林养分排放负荷是影响水环境保护质量的关键因素。本研究表明，气候变暖加速了凋落物分解，使凋落物成为潜在的分散森林污染源，流域排放负荷随陆地条件的变化而剧烈变化。实验和模型的结合可以提高弥散森林污染模拟的准确性，为制定流域气候变化适应策略提供有价值的信息。
