State Key Laboratory of Water Resources Engineering and Management, Wuhan University, Wuhan, Hubei 430072, PR China.
State Key Laboratory of Water Resources Engineering and Management, Wuhan University, Wuhan, Hubei 430072, PR China.
Sci Total Environ. 2024 Nov 10;950:175116. doi: 10.1016/j.scitotenv.2024.175116. Epub 2024 Jul 29.
Many evidences have shown that both atmospheric and soil droughts can constrain vegetation growth and further threaten its ability to sequester carbon. However, the trigger thresholds of vegetation production loss under different atmospheric and soil drought conditions are still unknown. In this study, we proposed a Copula and Bayesian equations-based framework to investigate trigger thresholds of various vegetation production losses under different atmospheric and soil drought conditions. The trigger thresholds dynamics and their possible causes were also investigated. To achieve this goal, we first simulated the gross primary production, soil moisture, and vapor pressure deficit over China during 1961-2018 using an individual-based, spatially explicit dynamic global vegetation model. The main drivers of the dynamic change in trigger thresholds were then explored by Random Forest model. We found that soil drought caused greater stress on gross primary production loss than atmospheric drought, with a larger impact area and higher probability of damage. In terms of spatial distribution, the risk probability of gross primary production loss was higher in eastern China than in western China, and the drought trigger threshold was also smaller in eastern China. In addition, the trigger thresholds for atmospheric and soil drought in most regions exhibited a decreasing trend from 1961 to 2018, while the CO fertilization enhanced the drought tolerance of vegetation. The reduction in CO fertilization effect slowed down the downward trend of trigger threshold for soil drought, while the increase in temperature exacerbated the downward trend of trigger threshold for atmospheric drought. This study highlighted the larger effect of soil drought on vegetation production loss than atmospheric drought and implied that climate change can modulate the trigger threshold of vegetation production losses under drought conditions. These findings provide scientific guidance for managing the increasing risk of drought on vegetation and optimizing watershed water allocation.
许多证据表明，大气干旱和土壤干旱都会限制植被生长，进一步威胁其固碳能力。然而，不同大气干旱和土壤干旱条件下植被生产力损失的触发阈值仍不清楚。在本研究中，我们提出了一种基于 Copula 和贝叶斯方程的框架，以研究不同大气干旱和土壤干旱条件下各种植被生产力损失的触发阈值。还研究了触发阈值的动态及其可能的原因。为了实现这一目标，我们首先使用基于个体的、空间显式的动态全球植被模型模拟了 1961-2018 年中国的总初级生产力、土壤湿度和水汽压亏缺。然后，通过随机森林模型探讨了触发阈值动态变化的主要驱动因素。我们发现，土壤干旱对总初级生产力损失的胁迫作用大于大气干旱，影响面积更大，破坏概率更高。就空间分布而言，中国东部地区的总初级生产力损失风险概率高于西部地区，干旱触发阈值也较小。此外，1961 年至 2018 年，大多数地区的大气干旱和土壤干旱的触发阈值呈下降趋势，而 CO 施肥增强了植被的耐旱性。CO 施肥效应的降低减缓了土壤干旱触发阈值的下降趋势，而温度的升高加剧了大气干旱触发阈值的下降趋势。本研究强调了土壤干旱对植被生产力损失的影响大于大气干旱，并暗示气候变化可以调节干旱条件下植被生产力损失的触发阈值。这些发现为管理干旱对植被日益增加的风险和优化流域水资源分配提供了科学指导。
