Phenotypic plasticity response of Great Plains grasses to environmental stress

Background/Question/Methods

Phenotypic plasticity, or the ability of a plant to respond to changing environmental conditions, may be a trait that increases a species invasive potential. In the Northern Great Plains, water availability is an environmental condition with significant intra- and inter-annual variation that influences plant distribution on the landscape. The goal of this project is to examine the phenotypic plasticity of cool-season native (Elymus canadensis, Pascopyrum smithii, and Poa secunda) and invasive (Bromus inermis, Poa pratensis, and Psathyrostachys juncea) plant species in response to drought, normal, and flood soil conditions. We ask the research question: Is phenotypic plasticity a trait that preferentially benefits invasive grass species in the Northern Great Plains? To address this question, we ran an experiment in a glasshouse with water treatments equivalent to drought conditions (lowest spring precipitation recorded in last 10 years), average conditions, and flood conditions (wettest spring precipitation recorded in last 10 years). To investigate each species’ response, we measured the above and below-ground biomass for each species in each treatment.

Results/Conclusions

Although, we found no significant difference in response of natives and non-natives (p=0.351, F=1.146 df= 5) to water treatments; significant differences were found among individual species (p<0.001, F= 5.108 df=25). For example, invader B. inermis produced equivalent biomass under flood and average conditions whereas invader P. pratensis biomass decreased in flood conditions. All species produced less biomass in the drought treatment, but P. pratensis was significantly more impacted, especially in root production, than other species. These results suggest that some of the invasive potential of B. inermis, but not P. pratensis may be due to the ability to respond to fluctuating water availability.