Integrating physiological threshold experiments with climate modeling to project mangrove species' range expansion

Area of Science:

• Ecology and Environmental Science
• Plant Physiology
• Climate Change Biology

Background:

• Correlative models are limited for predicting climate-driven species range shifts.
• Experimental approaches are needed to understand climate change impacts on species distributions.
• Mangrove distribution is influenced by climate, particularly extreme cold events.

Purpose of the Study:

• To identify physiological thresholds controlling the poleward range limits of North American mangroves.
• To develop a robust climate metric integrating freeze intensity and frequency.
• To project future range shifts of mangroves under climate change scenarios.

Main Methods:

• Controlled experiments were conducted to assess freeze tolerance thresholds in three mangrove species.
• A new climate metric, freeze degree days (FDD), was developed based on experimental data.
• FDD was integrated into distribution models and validated with satellite imagery of mangrove abundance.

Main Results:

• All three mangrove species showed threshold responses to extreme cold, with varying freeze tolerance.
• FDD accurately predicted mangrove presence/absence and correlated with observed changes in abundance.
• Climate projections indicate northward mangrove range shifts of 2.2-3.2 km/year over the next 50 years.

Conclusions:

• Physiological thresholds to extreme cold are critical determinants of mangrove distribution.
• Freeze degree days (FDD) is a valuable metric for predicting climate-driven range shifts.
• Mangrove ecosystems face significant poleward range expansion due to projected climate change.