Data from: Intraspecific variation among clones of a naïve rare grass affects competition with an invasive forb

Intraspecific variation can have a major impact on plant community composition yet there is little information available on the extent that such variation by an already established species affects interspecific interactions of an invading species. The current research examined the competitiveness of clones of a globally rare but locally common native grass, Calamagrostis porteri ssp. insperata to invasion by Alliaria petiolata, a non-native invasive species. A greenhouse experiment was conducted twice over consecutive years in which 15 clones from three populations of Calamagrostis were paired with rosettes of Alliaria in pots containing native forest soil previously uninvaded by Alliaria. Both species showed a negative response to the presence of the other species, although Alliaria more so than Calamagrostis. Moreover, the effect of Calamagrostis depended upon population, and, to a lesser extent, the individual clone paired with Alliaria. Competitive effects were stronger in the first experiment compared with when the experiment was repeated in the second year. The influence of Calamagrostis clones on the outcome of the experiment varied among populations and among clones, but also between years. Clones from one of the three populations were more influential than clones from the other two populations. Only one of 15 clones, both from the same population, were influential in both experiments. This research supports a growing literature indicating that intraspecific variability among clones of a dominant species can affect interspecific interactions, and that such variability in a native species can affect performance of an invading species.Biomass dataBiomass data of aboveground (above) and belowground (below) tissues of Calamagrostis and Alliaria plants from both years (year [1,2]) of the experiment. See ReadMe file for details.allbiomass.xlsxCalamagrostis_Tillerno_LeafnoLeaf and tiller number data of Calamagrostis plants from both years (year [1, 2]) of the experiment. Rows represent data from pots. There are column headers in row 1 plus 810 rows of data. See ReadMe file for details.Alliaria_dataLeaf and tiller number and leaf width data for Alliaria plants from both years (year [1,2]) of the experiment. Rows represent data from pots. There are column headers in row 1 plus 2970 rows of data. See ReadMe file for details