A catastrophic tropical drought kills hydraulically vulnerable tree species

Area of Science:

• Ecology
• Climate Change Biology
• Forest Science

Background:

• Drought-related tree mortality is increasing globally due to climate change.
• Identifying vulnerable species and drought response mechanisms remains challenging due to data limitations and unpredictable drought events.

Purpose of the Study:

• To investigate species-specific responses to extreme drought in a tropical forest.
• To determine the key traits predicting tree mortality during drought events.

Main Methods:

• Utilized long-term demographic data and functional trait databases for 20-53 species.
• Analyzed responses during the 2015 El Niño Southern Oscillation extreme drought event in a Costa Rican tropical forest.
• Correlated mortality rates with hydraulic safety margins, tree size, and leaf economics spectrum traits.

Main Results:

• Species-specific mortality rates varied from 0% to 34% and were independent of tree size.
• Hydraulic safety margins strongly correlated with species' probability of mortality.
• Morphological and leaf economics traits did not predict drought-induced mortality.

Conclusions:

• Hydraulic safety margins are critical indicators of drought vulnerability in tropical trees.
• Future research should focus on hydraulic traits to predict and mitigate drought-related tree mortality.
• Understanding these mechanisms is crucial for managing forests under future climate scenarios.