PARENT SESSION
Contributed Oral Session 142: Biodiversity and Nitrogen
Thursday, August 11, 1:30 PM - 5:00 PM, Meeting Room 521 A, Level 5, Palais des congrès de Montréal
Development of the diversity - productivity relationship during community re-assembly is constrained by propagule availability.
Foster, Bryan*,1, Murphy, Cheryl1, Dickson, Timothy1, Karel, Irene1, Collins, Cathy1, Questad, Erin1, 1 University of Kansas, Lawrence, Kansas
ABSTRACT- Rates of community re-assembly and species accumulation during secondary succession can be constrained by local biotic interactions, local resource supply and by factors that limit the rate and sequence of propagule arrival to the focal habitat. We present initial results from an ongoing field experiment that was designed to examine the impacts of soil nutrient supply and propagule pools on patterns of secondary succession and dynamics leading to the development of plant diversity-productivity relationships in Kansas grassland. The experiment is comprised of a 4 x 2 x 2 factorial set of treatments applied to 96 4m x 5m field plots. Experimental factors include: nitrogen availability (four levels of N fertilization); phosphorus availability (two levels of P fertilization); and plant propagule availability (2 levels: no seeds versus the addition of seeds from 50 plant species). As measured in years three and four of succession on previously-plowed soil, plant productivity was increased significantly by nitrogen fertilization. Plant colonization rate and species richness were increased significantly by sowing, but to a greater extent at low than at high rates of nitrogen supply (sowing x N fertilization interaction). By the fourth year of succession, plant species richness, evenness and the Shannon diversity index had become significantly correlated with aboveground plant productivity, but only in plots that had received enhanced propagule inputs (sowing x productivity interaction). In the presence of an enhanced propagule pool, species richness and Shannon diversity both exhibited a unimodal relationship to plant productivity. These findings suggest that development of the relationship between plant species diversity and plant productivity during succession is sensitive to the pool of colonists available to undergo species sorting along landscape gradients in resource availability.
Key words: community assembly, diversity productivity relatiosnhip, propagule availability, succession