PARENT SESSION
Oral Session 141: Ecological Theory V: Dispersal; Nutrient Cycling.
Presiding: T Baisden
Friday, August 6, 8:30 AM to 12:00 PM, Meeting Room D 139.

The effect of recycling on plant competitive hierarchies.

Clark, Benjamin^*,1, de Mazancourt, Claire¹, Suding, Katharine², Hartley, Sue³, ¹ Department of Biological Sciences and NERC Centre for Population Biology, Ascot, Berkshire, United Kingdom² School of Biological Sciences, Irvine, California, U.S.A.³ School of Biological Sciences, Brighton, Sussex, United Kingdom

ABSTRACT- Evidence from field studies suggest that plant species affect the nutrient status of their local environment through positive feedback via recycling nutrients in their litter. Here we examine the mechanisms behind this process using simple mathematical models of nutrient flow. The models were used to examine if and how recycling affects plant growth, competition and coexistence, and to examine which plant properties should be important in determining successful competitors for nutrients. It was found that, at equilibrium, turnover rates of nutrients ("rapid" and "slow" decomposition) did not affect the outcome of competition or the nutrient availability. Only the transient dynamics of an ecosystem (i.e. successional processes) are affected by the rate of turnover. However, by effectively removing nitrogen from the ecosystem forever by producing recalcitrant litter, species can affect their long term persistence. These effects are only found when nitrogen is accessed in different forms, or if plant growth rate is limited at high nitrogen availability.

Key words: recycling, resource competition, nitrogen, model