Predicting plant vulnerability to drought in biodiverse regions using functional traits

Area of Science:

• Plant physiology
• Ecology
• Drought stress mechanisms

Background:

• Plant mortality during drought is often linked to hydraulic strategies.
• Existing hydraulic frameworks distinguish isohydric (high water potential) and anisohydric (carbon assimilation) strategies.
• Testing these frameworks in diverse communities is challenging due to a lack of standardized values.

Purpose of the Study:

• To develop and test a standardized system for quantifying plant hydraulic strategies in biodiverse communities.
• To link stomatal regulation and xylem vulnerability to plant mortality mechanisms under drought.
• To establish a framework for predicting drought responses in diverse plant communities.

Main Methods:

• Quantified hydraulic strategy using indices from vulnerability curves and stomatal dehydration response curves.
• Defined degree of stomatal regulation over cavitation as the margin between Px at stomatal closure (Pg12) and Px at 50% loss of conductivity.
• Developed proxies for carbon limitation and hydraulic failure using time since Pg12 and conductivity loss at minimum seasonal Px.

Main Results:

• The developed approach captured continuous variation along an isohydry/anisohydry axis.
• This variation was linearly related to the xylem safety margin.
• Degree of isohydry/anisohydry was associated with contrasting predictions for drought-induced mortality.

Conclusions:

• Merging stomatal regulation strategies with xylem vulnerability provides a comprehensive framework for plant drought response.
• This framework facilitates prediction of diverse plant community responses to future droughts.
• The study offers a novel method to assess plant hydraulic strategies and their link to mortality.