Continent-wide tree fecundity driven by indirect climate effects

Area of Science:

• Ecology
• Forest Science
• Climate Change Biology

Background:

• Current forest models often overlook indirect climate effects on tree fecundity via size and growth.
• Predicting species abundance shifts requires understanding individual tree responses to climate-driven conditions.

Purpose of the Study:

• To investigate how climate-condition interactions influence tree fecundity through growth and size pathways.
• To assess the biogeographic variation in these climate-fecundity interactions across North America.

Main Methods:

• Synthesized data from multiple North American tree species.
• Analyzed indirect climate effects on fecundity mediated by tree growth and size.

Main Results:

• Climate-condition interactions significantly impact tree fecundity through two main pathways: climate-dependent growth and size-dependent climate effects.
• Tree fecundity's non-linear response to size means climate change can shift populations towards or away from optimal reproductive sizes.
• A clear biogeographic divide was observed, with interactions reducing fecundity in Western North America and increasing it in the East.

Conclusions:

• Indirect climate effects, mediated by tree size and growth, are critical drivers of continental-scale forest responses.
• Future forest predictions and management strategies must incorporate these complex demographic rate interactions to account for climate change impacts.