基于DNDC模型的高寒草甸土壤有机碳含量动态研究

研究发现以气温升高为主导的气候变化严重影响高寒草甸土壤有机碳含量的动态变化,然而,关于气候变化和放牧对土壤有机碳的耦合效应知之甚少。本研究采用增温-放牧试验结合DNDC(denitrification-decomposition)模型,检测气候变化和放牧对青藏高原高寒草甸土壤有机碳含量的影响,并评估气候变化和放牧对土壤有机碳含量变化的贡献率。结果表明:气候变化对土壤有机碳产生负面影响;放牧强度通过增加践踏、落叶和粪便返还影响土壤有机碳含量。温度、降水结合放牧强度,解释了高寒草甸土壤有机碳含量变化的63.4%。气候变化是导致土壤有机碳波动的主要因素,该因素解释了土壤有机碳变化的61.9%。相比之下,放牧强度解释了其变化的1.6%。持续的气候变化和放牧会影响土壤有机碳的动态变化,进而影响草地生态系统的服务功能。草地生态系统管理应考虑到潜在的气候变化,以实现该系统的可持续发展。

A ‘denitrification-decomposition’ (DNDC) model evaluation of alpine meadow soil carbon response to climate change

It has been demonstrated that climate change and associated warming has affected the soil organic carbon (SOC) in alpine meadows over past decades, but little is known about the coupling between climate change and grazing. In this research, an experiment incorporating controlled warming and grazing was used in conjunction with a denitrification-decomposition (DNDC) model to evaluate the contributions of climate change and grazing to changes in SOC in an alpine meadow ecosystem on the Tibetan Plateau. It was found that climate change influenced SOC negatively; while grazing intensity was an external factor that further modified SOC through trampling, defoliation and manure return. The model explained 63.4% of the observed change in SOC. Specifically, climate change (temperature and precipitation) was the major factor affecting SOC, and explained 61.9% of the variation in SOC. By contrast, grazing intensity explained 1.6% of the variation in SOC. These findings show that ongoing climate change and grazing can be expected to reduce SOC in alpine meadow ecosystems, potentially hindering their ability to provide ecosystem functions and services for human well being. Grassland ecosystem management should consider potential climate change effects to achieve sustainable development in this region.