PARENT SESSION
Oral Session #40: Biodiversity and Ecosystem Function: Do species and species richness matter?. Presiding: R. Dirzo.
Wednesday, August 8, 2001. 8:00 AM to 12:00 PM. Madison Ballroom D.

Complementarity, compensation, & competition: what goes around, comes around.

Ewel, John¹, ¹

ABSTRACT- Interactions among plant species, which in turn influence functional attributes of ecosystems, depend upon the traits of species involved. A nine-year study of additive mixtures of three species revealed that the nature of those interactions is not constant but change over time as individuals achieve greater stature or access new resources. The research was done in the lowland humid tropics and involved three life forms: tree, palm, and perennial herb. Net primary productivity was assessed annually as a measure of efficacy of resource capture and conversion to biomass. A species combination that had, at age 3 years, exhibited complementary resource use among life forms showed compensatory growth at age 9; one that showed compensatory growth at age 3 switched to competition by a dominant life form at age 9; and one that showed competition by a dominant at age 3 exhibited complementarity at age 9. Although biodiversity and ecosystem functioning relationships are not static, they may be predictable. If so, the relationships can be important predictors of ecosystem processes during succession and through the course of restoration.

KEY WORDS: productivity, tropics, biodiversity, restoration