Is there tree senescence? The fecundity evidence

Area of Science:

• Ecology
• Forest Science
• Plant Physiology

Background:

• Tree fecundity is crucial for forest regeneration, food webs, and economies.
• Current ecological models often assume fecundity increases with tree size (allometric scaling).
• Existing data may overrepresent smaller trees, potentially skewing understanding of large tree contributions.

Purpose of the Study:

• To investigate how tree fecundity changes with tree size and age.
• To compare observed size-fecundity relationships with traditional allometric models and crown architecture models.
• To provide a more accurate understanding of seed production for improved forest dynamic models.

Main Methods:

• Compiled global tree fecundity data, ensuring representation of large trees.
• Analyzed size-fecundity relationships using regression models.
• Compared empirical data against established allometric scaling and crown architecture models.

Main Results:

• Allometric models failed to accurately describe the size-fecundity relationship for 80% of the 597 studied species.
• A declining rate of fecundity increase with diameter was observed in most species.
• This decline suggests physiological limitations in large trees, not solely explained by crown architecture.

Conclusions:

• Tree fecundity does not consistently increase with size as assumed in many ecological models.
• Physiological decline likely limits seed production in large trees.
• Revised fecundity projections for large trees are needed for more accurate forest dynamic modeling.