Climatic effects on trade-offs between carbon and water cycle on the Yangtze River Basin, China

It is widely believed that forest plays a vital role in mitigating and adapting climate changes. By adopting afforestation and reforestation, the atmospheric carbon can be captured and stored (sequestered) within plants and soil. Thus, tree expansions are witnessed over the whole world. However, large-scale forestation often requires a high amount of water resources, which may bring up pressures on the local water cycle. In this case, trade-offs between carbon sequestration and ecohydrology remain under discussion yet.China has launched several forestation projects since the last century. These projects spread over the country in both water-sufficient and water-limited areas. However, the changing climate conditions may alter local ecosystems and influence the survival of newly grown vegetations and the potential of carbon sequestration. Therefore, understanding the influences of climate change on carbon sequestration and hydrological response is of importance in national forestation management.In this study, we selected a Dynamic Global Vegetation Model (DGVM), the Lund–Potsdam–Jena Managed Land (LPJmL4), to study climatic influences on the carbon cycle and water cycle in the Yangtze River Basin, China. The model was implemented on a regional scale with increased resolution from 30mins to 5mins. Meanwhile, considering the complex terrain of the Yangtze River Basin, we classified the basin with a climatic zonation scheme to furtherly analyse the influence of climate.Our initial findings indicated that climate effects dominated the variations in the carbon and water cycle. Meanwhile, the future focus of ecological restoration, including forestation and protection, might need to shift from subtropical regions like the Yunnan-Guizhou plateau to western temperate alpine regions. This work can serve as recommendations for guiding national ecological restoration management.