Warming induces divergent stomatal dynamics in co-occurring boreal trees

Area of Science:

• Ecology
• Plant Physiology
• Climate Change Research

Background:

• Climate warming affects plant photosynthesis and respiration through temperature and atmospheric dryness.
• Most data on warming effects come from controlled seedling studies, with limited knowledge on mature field-grown trees.

Purpose of the Study:

• To investigate the impact of whole-ecosystem warming on leaf gas exchange in mature tamarack and black spruce trees.
• To understand species-specific responses to warming and vapor pressure deficit in a peatland ecosystem.

Main Methods:

• Utilized the Spruce and Peatland Responses Under Changing Environments (SPRUCE) experiment with whole-ecosystem warming up to +9°C.
• Monitored leaf gas exchange, leaf nitrogen, and dark respiration in mature tamarack and black spruce over two years.

Main Results:

• Warming increased leaf nitrogen in both species, but only boosted photosynthesis in tamarack.
• Spruce photosynthesis was more limited by stomatal conductance under warming than tamarack.
• Dark respiration did not acclimate to warming in spruce; tamarack showed acclimation after accounting for leaf nitrogen changes.

Conclusions:

• Mature tamarack and black spruce exhibit divergent stomatal and photosynthetic responses to climate warming.
• Species-specific physiological adjustments influence carbon and water dynamics in warming peatland ecosystems.
• Understanding these differences is crucial for predicting forest ecosystem responses to climate change.