The role of ecotypic variation and the environment on biomass and nitrogen in a dominant prairie grass

Abstract

Abstract. Knowledge of the relative strength of evolution and the environment on a phenotype is required to predict species responses to environmental change and decide where to source plant material for ecological restoration. This information is critically needed for dominant species that largely determine the productivity of the central U.S. grassland. We established a reciprocal common garden experiment across a longitudinal gradient to test whether ecotypic variation interacts with the environment to affect growth and nitrogen (N) storage in a dominant grass. We predicted plant growth would increase from west to east, corresponding with increasing precipitation, but differentially among ecotypes due to local adaptation in all ecotypes and a greater range of growth response in ecotypes originating from west to east. We quantified aboveground biomass, root biomass, belowground net primary production (BNPP), root C:N ratio, and N storage in roots of three ecotypes of Andropogon gerardii collected from and reciprocally planted in central Kansas, eastern Kansas, and southern Illinois. Only the ecotype from the most mesic region (southern Illinois) exhibited more growth from west to east. There was evidence for local adaptation in the southern Illinois ecotype by means of the local vs. foreign contrast within a site and the home vs. away contrast when growth in southern Illinois was compared to the most distant site in central Kansas. Root biomass of the eastern Kansas ecotype was higher at home than at either away site. The ecotype from the driest region, central Kansas, exhibited the least response across the environmental gradient, resulting in a positive relationship between the range of biomass response and precipitation in ecotype region of origin. Across all sites, ecotypes varied in root C:N ratio (highest in the driest-origin ecotype) and N storage in roots (highest in the most mesic-origin ecotype). The low and limited range of biomass, higher C:N ratio of roots, and lower N storage in the central Kansas ecotype relative to the southern Illinois ecotype suggests that introducing ecotypes of A. gerardii from much drier regions into highly mesic prairie would reduce productivity and alter belowground ecosystem processes under a wide range of conditions.

Genetic differentiation and plasticity interact along temperature and precipitation gradients to determine plant performance under climate change

“…; Kim & Donohue ; Mendola et al . ; Malyshev et al . ) and reviews of older studies in Hereford () and Alberto et al .…”

Ecotypic variation in forage nutrient value of a dominant prairie grass across a precipitation gradient

“…,b; Mendola et al . ). However, variation in forage nutrient value of these naturally developed ecotypes of A. gerardii across this precipitation gradient is not known.…”

Phenotypic distribution models corroborate species distribution models: A shift in the role and prevalence of a dominant prairie grass in response to climate change

“…Will A. gerardii remain an important species of the central grassland ecosystem? Given that phenotypic variation in this species is in large part genetically controlled (Gray et al., ; Johnson et al., ; Mendola et al., ) and not because of phenotypic plasticity, for several reasons we expect that A. gerardii will likely not be able to acclimate or adapt quick enough to future climate conditions. First, most reproduction in this species is asexual through rhizomes’ production of clones (Weaver & Fitzpatrick, ).…”

“…Our results suggest that the small‐statured phenotypes characteristic of the dry western shortgrass prairies will become favored in the current core distribution where tallgrass forms currently predominate. These changes have important implications for diversity and productivity of restored prairies (Collins et al., ; Mendola et al., ), the livestock industry (Rogler, ), and bioenergy production (Zhang et al., ). The degree to which the species will actually respond in a manner that matches our predictions depends on the potential for in situ selection (Jump & Peñuelas, ; Shaw & Etterson, ), sexual reproduction, and dispersal to more suitable sites, perhaps aided by assisted gene flow (Aitken & Whitlock, ; Broadhurst et al., ; Hufford & Mazer, ).…”

“…Consistent with these observations, A. gerardii increases in stature and productivity with increasing precipitation (Epstein et al., ; Johnson et al., ; McMillan, ; Olsen, Caudle, Johnson, Baer & Maricle, ). Tellingly, a reciprocal common garden experiment established across a ~1200 km transect from western Kansas to Illinois demonstrated local adaptation and strong genetic control over growth‐related traits in this species (e.g., biomass, height; Johnson et al., ; Mendola et al., ). The strong correlation between growth and climatic gradients (Gray et al., ; McMillan, ) suggests that adaptive, genetically controlled phenotypic differences could play an important role in predicting the distribution of A. gerardii in response to climate change.…”