# Vegetation Health in China Is Severely Compromised by Drought, Wet and Heat Stress Events
###### Abstract  
Stress events induced by global warming pose severe threats to vegetation health. Assessing the impact of these stress events on the health and growth of vegetation ecosystems in China is crucial. This study constructed three vegetation health assessment systems and selected the one that most effectively reflects vegetation health. By identifying the characteristics of stress events, and employing trend analysis, sensitivity analysis, anomaly change analysis, and modified residual analysis, this study explores the dynamic changes in vegetation health and their responses to stress events across China from 2001 to 2020. The results indicate that the Pressure-State-Response (PSR) model has the best evaluation performance, achieving the highest fit to Solar-Induced Chlorophyll Fluorescence (SIF) with an goodness of fit (R\({}^{2}\)) of up to 0.74. Overall, vegetation health exhibits more negative anomalies than positive ones and shows the strongest positive sensitivity to Cumulative Precipitation Anomaly (CPA) and the strongest negative sensitivity to Cumulative Heat (CH). Among different vegetation types, alpine vegetation has the highest stability in health, while meadows and grasslands are the most sensitive to stress events. Additionally, stress events have a greater contribution rate to vegetation health than other events. Our findings will provide important data for climate change adaptation policies and extreme environmental early warning while also contributing to the formulation of policies aimed at improving vegetation health. These results are of significant importance for enhancing carbon sequestration capacity, refining carbon market policies, and promoting the sustainable development of ecosystems. v 2024 2020 27 December 2024 2020 27 December 2024 2020 27 December 2024 2020 27 December 2024 2020 27 December 2024 2020 27 December 2024 2020 27 December 2024 2020 27 December 2024 2020 27 December 2024 2024 2024 2024 2024 2024 2024 202  
ing the impact of stress events on vegetation health is crucial for the stable and healthy development of ecosystems in the face of climate change. Stress events impact vegetation health through carbon storage, water cycling, and changes in biodiversity, while temperature and moisture are key factors influencing vegetation growth [7; 8]. Amidst the continuous breaking of global temperature records, the carbon sequestration capacity of vegetation has markedly declined, particularly compromising the health of crops and natural vegetation [9]. Heat stress inhibits plant growth by exacerbating water stress in plants [10; 11]. The 2003 European heatwave led to a 30% decline in total primary productivity of vegetation [12], and the 2018 slowdown in the growth rate of forests and grasslands in China also serves as evidence [13]. Accompanying heat stress, the most pronounced is drought stress. Drought, one of the most widespread and common natural disasters in China [14], is characterized by an imbalance between water supply and demand and has significant ecological and socioeconomic consequences. Drought stress reduces soil moisture and limits plant water use efficiency, thereby greatly reducing photosynthetic efficiency and plant productivity [15; 16]. This accelerates ecosystem degradation and leads to a sharp decline in biodiversity [17; 18]. Drought stress typically accompanies heat stress [19], while heat stress events increase the probability of precipitation [20]. Wet stress, or excessive rainfall, leads to insufficient soil oxygen, inhibiting root respiration and nutrient absorption, thereby affecting plant growth and health [21]. Under the influence of global warming, extreme precipitation events have exacerbated the vulnerability of ecosystems in areas prone to soil erosion, such as the Loess Plateau, while benefiting vegetation growth in coastal regions [22]. For instance, wet stress during the rainy season in southeast China has increased vegetation cover by 5% to 10% [23].