Submitted to: American Institute of Biological Sciences
Publication Type: Abstract Only
Publication Acceptance Date: March 2, 2000
Publication Date: August 3, 2000
Citation: Tracy, B.F., Sanderson, M.A. 2000. Plant diversity, community stability, and ecosystem function in northeast grasslands [abstract]. American Institute of Biological Sciences. p.42. Technical Abstract: We have been studying the ecology of grassland/pasture ecosystems in the northeast United States since 1997. The overarching question of our work asks whether we need to increase plant diversity in these grasslands to improve their sustainability. Through intensive survey work in 1998, we found that northeast pastures were surprisingly diverse. A total of 161 different plant species was found across the northeast study region with a average of 32 species/1000 m2. Species richness in pastures was also similar to many native grasslands at both 1 m^ 2 and 1000 m ^ 2 scales. We also designed a field experiment using different levels of species richness (1-15 species) to learn how these would affect ecosystem function. Specifically, we wanted to know: (1) how different levels of plant diversity affected aboveground production under simulated rotational grazing, and (2) how these differences in aboveground plant diversity affected belowground variables like root biomass, microbial respiration an soil nitrate concentrations. Additionally, a drought during the 1999 growing season allowed us to test hypotheses about diversity-stability relationships in pasture plant communities. Overall, plant functional group diversity, not species diversity per se, controlled most of the seasonal variation in primary production. We found little evidence for increased community stability with greater plant diversity. Stability, instead, depended mostly on characteristics of individual species, and how certain combinations of functional groups interacted following disturbance. We conclude that more research should focus on ways to predict combinations of plant functional groups that will yield the most sustainable grassland ecosystems for differing environmental conditions.