PARENT SESSION
Oral Session # 62: Biodiversity I.
Presiding: P Baker
Thursday, August 7. 8:00 AM to 11:30 AM, SITCC Meeting Room 100.

From selection to complementarity: Temporal trends in a long-term biodiversity experiment.

Fargione, Joe^*,1, Dybzinski, Ray¹, Clark, Chris¹, Hille Ris Lambers, Janneke¹, Harpole, Stan¹, Loreau, Michel², Tilman, David¹, ¹ University of Minnesota, St. Paul, MN² Ecole Normale Supérieure, Paris, France

ABSTRACT- A long term biodiversity experiment at Cedar Creek Natural History Area demonstrates that productivity increases as a function of plant species richness. This positive effect of biodiversity on productivity has grown stronger over the seven years that data have been collected, and may be due to the increased likelihood of diverse mixtures containing productive species (ie a selection or sampling effect) or positive interactions among species (ie a complementarity effect). We partitioned the net biodiversity effect into selection and complementarity components using the statistical techniques of Loreau and Hector (2001). We found a positive selection effect in the first two years of data, and a positive complementarity effect in the remaining five years of data. Thus, the mechanisms controlling the positive relationship between diversity and productivity shifted from selection to complementarity over time. We further partition these selection and complementarity effects by individual species. We show that the complementarity effect of 8 of 16 species in the experiment significantly increased over time. Our results highlight the importance of long-term experiments in understanding biodiversity effects.

Key words: complementarity, Biodiversity, sampling, selection