Exacerbated drought impacts on global ecosystems due to structural overshoot

Area of Science:

• Ecology
• Climate Science
• Environmental Science

Background:

• Vegetation dynamics are influenced by both current climate and lagged responses from past conditions.
• Favorable past climates can stimulate vegetation growth beyond ecosystem carrying capacity, leading to structural overshoot.
• Structural overshoot can increase ecosystem vulnerability to climate stresses, potentially causing widespread drought and forest mortality.

Purpose of the Study:

• To identify and characterize ecosystem structural overshoot globally using a dynamic statistical learning approach.
• To quantify the drought impacts associated with structural overshoot.
• To understand the factors influencing the prevalence of overshoot droughts.

Main Methods:

• Employed a dynamic statistical learning approach to analyze vegetation dynamics and climate data.
• Identified and characterized instances of ecosystem structural overshoot on a global scale.
• Quantified the contribution of structural overshoot to drought events and assessed associated impacts.

Main Results:

• Structural overshoot contributed to approximately 11% of drought events between 1981 and 2015.
• Overshoot-related droughts are often linked to compound extreme drought and heat, resulting in faster vegetation declines.
• The prevalence of overshoot droughts is primarily driven by mean annual temperature, with biodiversity, aridity, and land cover as secondary factors.

Conclusions:

• Vegetation dynamics, specifically structural overshoot, play a significant role in drought development.
• Warming-induced increases in vegetation may lead to more frequent and severe overshoot droughts in the future.
• Understanding vegetation memory is crucial for predicting drought impacts and ecosystem resilience.