Submitted to: International Grasslands Congress
Publication Type: Abstract only
Publication Acceptance Date: 1/29/2005
Publication Date: 7/1/2005
Citation: Goslee, S.C., Sanderson, M.A., Soder, K.J. 2005. Species richness, species identity and ecosystem function in managed temperate grasslands. International Grasslands Congress. p. 162. Interpretive Summary: An interpretive summary is not required.
Technical Abstract: Manipulation of plant species diversity may provide a way to improve the ecosystem functioning of managed systems by increasing productivity and suppressing weedy species. As yet, the functional role of species richness is not well-enough understood to enable practical application. We investigated the effects of differing species richness on community stability and invasion resistance in a grazed temperate grassland. Nine plant species from three different functional groups (grass, legume, forb) were planted in the fall of 2001 at University Park, PA, USA, in mixtures of 2, 3, 6, and 9 species, and rotationally grazed by dairy cattle during 2002 and 2003. Higher richness conferred an establishment advantage; planted species richness was positively correlated with total cover in fall 2001 and spring 2002. Although cover of unplanted (weedy) species declined with increasing richness on these dates, there was no difference in the number of unplanted species. After the first year there were no significant trends in cover or richness between the treatments. The lowest-richness treatment was most affected by summer drought, but all treatments recovered. The forb Cichorium intybus, part of the 3, 6 and 9 species mixtures, established rapidly and contributed greatly to the early success of these treatments. Several other grasses and legumes increased in abundance over the first year, then declined. The higher-species treatments lost planted species over time, even when those species persisted in the lower-species mixtures. By the end of the study, the same species (Dactylis glomerata in all treatments and Trifolium repens in 2, 3 and 9-species mixes) were dominant regardless of initial seeding composition. Species identity was more important to cover and invasion resistance than was species richness. Management recommendations based on particular combinations of species may be more effective at improving ecosystem function than those based solely on species richness. If high plant diversity is desired, the management regime must support the maintenance of that diversity or, as in this study, species will tend to disappear from the higher-richness treatments.