PARENT SESSION
Oral Session #77: Biodiversity and Ecosystem Function II.
Presiding: G. Chong
Thursday, August 8. 9:00 AM to 11:30 AM. Coconino Meeting Room, TCC.

Coexistence and relative abundance in forest trees.

KELLY, COLLEEN^*,1,2, BOWLER, MICHAEL², ¹ University of Southampton, Southampton, UK² University of Oxford, Oxford, UK

ABSTRACT- Contemporary acceleration of biodiversity loss makes understanding the controls of species coexistence of increasing urgency. Tree diversity in particular plays a pivotal role in determining terrestrial biodiversity, through maintaining diversity of its dependent species and with them, their predators and parasites. The majority of theories of coexistence based upon the Principle of Limiting Similarity generally suggest that coexistence of competing species is inherently unstable; coexistence of competitors must be maintained by external forces such as disturbance, immigration or 'patchiness' of resources in space and time. In contrast, storage theory postulates stable coexistence of competing species through temporal alternation of conditions favouring recruitment of one species over the other. We have developed from storage theory explicit predictions for relative differences between competitors that allow discrimination among coexistence models. Data on tree species from a primary forest on the Mexican Pacific coast show support for a general dynamic of storage processes determining coexistence of similar tree species in this community, and rejection of all other theories of coexistence. We thereby offer the first definitive evidence for storage dynamics as a general determinant of species coexistence.

KEY WORDS: plant rarity, storage theory, tropical deciduous forest, México