Submitted to: Ecological Society of America Abstracts
Publication Type: Abstract only
Publication Acceptance Date: 4/23/2005
Publication Date: 6/20/2005
Citation: Collins, S.L., Calabrese, L., Smith, M.D., Fay, P.A. 2005. Climate drivers and rate of change in mesic and arid grasslands. In: Ecological Society of America Proceedings, August 7-12, Montreal, Canada. 2005 CDROM. Interpretive Summary:
Technical Abstract: Interannual climate variability has a strong impact on vegetation dynamics in herbaceous plant communities. The importance of climate effects may vary, however, across a mesic to xeric gradient as growing season rainfall events become more discrete in arid ecosystems. Using vegetation data from long-term permanent plots and three rainfall manipulation experiments we compare the effects of interannual variation in climate on grassland dynamics in mesic and xeric grasslands. Study sites include mesic tallgrass prairie at the Konza Prairie LTER in northeastern Kansas and desert grassland at the Sevilleta LTER site in central New Mexico USA. At both sites, annual net primary production is positively correlated with growing season precipitation. Species richness and richness of forbs are also correlated with interannual variation in precipitation, yet these correlations are relatively weak at both sites. There is a strong negative correlation between grass and forb abundance in mesic prairie, but not in the xeric grassland. The desert grassland contains a larger number of annual species and there is a strong, positive relationship between winter precipitation and abundance of spring annuals at the Sevilleta. At the mesic site, fire and grazing have a greater influence on community dynamics than does interannual variability in climate, whereas plant community response in the ungrazed desert grassland where fires are infrequent is strongly driven by within-season water availability. Vegetation at both sites is changing over time in response to changes in climate. Overall, our results suggest that biotic interactions have a stronger influence than interannual climate variability on grassland dynamics in mesic prairie compared to xeric grassland.