Global variations in critical drought thresholds that impact vegetation.

Area of Science:

• Ecology
• Climate Science
• Remote Sensing

Background:

• Quantifying ecosystem responses to climate variability and change requires identifying drought thresholds that impact vegetation functioning.
• Understanding these thresholds is vital for predicting land ecosystem behavior under changing climatic conditions.

Purpose of the Study:

• To develop a globally applicable framework for identifying drought thresholds impacting vegetation responses to soil-moisture deficits.
• To assess the geographical variation in these thresholds and compare them with land model estimations.

Main Methods:

• Utilized four remotely sensed vegetation proxies from 2001-2018 to establish a framework for identifying drought thresholds.
• Analyzed vegetation responses to varying levels of soil-moisture deficits across different ecosystems.

Main Results:

• Identified critical drought thresholds indicating shifts in vegetation vulnerability, varying geographically.
• Found that forested ecosystems, particularly in humid climates, exhibit lower soil-moisture anomaly thresholds, indicating greater resilience.
• Observed that current land models overestimate drought thresholds, especially in humid, forested, and arid, non-forested areas.

Conclusions:

• Drought thresholds are geographically variable, with forests offering significant mitigation capacity.
• Land models require refinement as they currently overestimate drought thresholds.
• Future climate projections suggest an increased risk of vegetation damage in specific global hotspots by the end of the 21st century.