Natural populations of plants frequently exhibit intraspecific variation in phenotypes, and this variation can directly impact community and ecosystem processes by influencing species’ net productivity, competitive ability and the community’s ability to respond to disturbance. In the semi-arid Great Basin Desert, an area spanning five Western states, limited water and soil nutrients drive complex competitive and facilitative interactions within plant communities. Understanding phenotypic variation in this region is important because this variation may represent local adaptation, and can influence the maintenance of biodiversity and resilience of communities. We sought to determine 1) how functional traits differ by species among populations and 2) whether species from the same population were more similar in functional traits for six native species (representing shrubs, grasses, and forbs): Achnatherum thurberianum, Artemisia tridentata, Chaenactis douglasii, Elymus elymoides, Ericameria nauseosa, and Poa secunda. We collected seeds from six ecologically and geographically distinct populations within the Great Basin for each species, and established a long-term common garden in Reno, NV in October 2016. Plants were monitored for emergence, survival, timing of flower and seed production, final number of inflorescences, late-season vigor and aboveground growth.
Results/Conclusions
Populations exhibited substantial differentiation in almost every functional trait. Aboveground size and height of five species of grasses and shrubs varied significantly by source population (all P < or = 0.0144). Only two species had flowering individuals in 2017, and for these, heading date, blooming date, and number of inflorescences all differed by source population. The most dramatic differences among source populations were in field-collected seed weights (all P < 0.0001), which differed for the five species we weighed; F1 seed weights also differed significantly among populations (P < 0.0001) for the two species that flowered in our common garden. While populations differed in functional traits in all study species, species from the same population were not similar in size and phenological traits, indicating the potential for differential selection for individual species at the same location. These results lay the foundation for understanding trait variation among functional groups in the Great Basin and provide a basis for further work to ask how phenotypic variation and community composition affect restoration outcomes. The differences among our studied populations’ phenotypes indicates that field performance would be likely to differ among populations, which has implications for their use in restoration seedings and the resulting community’s success and resilience.