Rainfall Manipulation Plots facility (RaMPs) is a unique experimental infrastructure that allows us to manipulate precipitation events and temperature, and assess population community, and ecosystem responses in native grassland. This facility allows us to manipulate the amount and timing of individual precipitation events in replicated field plots at the Konza Prairie Long-Term Ecological Research (LTER) site.
We used data from a unique 15-year long rainfall manipulation experiment at the Konza Prairie Biological Station in northeastern Kansas, USA, to determine how altered precipitation patterns (fewer, larger events) impacted plant species composition and structure in an annually burned, ungrazed, native tallgrass prairie. We tested two hypotheses. First, based on the HRF, we predicted that directional change in grass and forb cover and richness and community composition would eventually occur after a lag period under the altered precipitation treatment. Second, we predicted that change in cover and composition under altered precipitation would be driven by the response of forbs more so than grasses because the dominant grasses are reported to be buffered against precipitation variability1,44 and changes in the cover and richness of forbs contribute disproportionately to community responses to other drivers in this grassland.
Aboveground NPP and species composition:
ANPP is estimated from end of season harvests of sixteen 0.1 m2 quadrats per RaMP, eight from heated areas and eight from ambient temperature areas. All biomass is sorted into graminoid and forb components. Because the site is burned annually and not grazed, the biomass harvested represents ANPP. Canopy cover, plant species richness and diversity are estimated in 1-m2 permanent plots in each RaMP (twice in a growing season to sample early and late season species; Collins et al. 1998). Pretreatment data were collected in 1997 from all RaMP plots and was collected prior to warming the subplots.
For more inforamtion about this study, please see: www.konza.ksu.edu/ramps/