Mast seeding under increasing drought: results from a long-term data set and from a rainfall exclusion experiment

Area of Science:

• Ecology
• Botany
• Environmental Science

Background:

• Mast seeding, characterized by synchronous, variable seed production, is common in trees but its drivers remain debated.
• Understanding environmental influences on masting is crucial for predicting forest dynamics and tree recruitment.

Purpose of the Study:

• To identify environmental drivers of mast seeding variation in Quercus ilex.
• To contrast climate versus adaptive factors in masting.
• To assess drought impacts on reproductive processes under global change scenarios.

Main Methods:

• Analysis of a 26-year dataset on Quercus ilex reproductive and vegetative growth.
• A rainfall exclusion experiment simulating drought conditions.

Main Results:

• Seed production is strongly influenced by water availability during spring and summer.
• Torrential rain events negatively affect late-stage seed development.
• Masting is primarily a physiological response to environmental variability, not solely endogenous rhythms.

Conclusions:

• Seed development success, rather than flowering effort, determines mast year variation.
• Predicted drier conditions due to climate change may reduce seed production, negatively impacting tree recruitment and forest dynamics.