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.

种内变异（Intraspecific variation）可对植物群落组成产生显著影响，但目前关于已定殖物种的此类变异如何影响入侵物种种间相互作用（interspecific interactions）的研究仍较为匮乏。本研究探究了全球稀有但局部分布常见的本土禾草Calamagrostis porteri ssp. insperata的克隆株（clone）对入侵物种Alliaria petiolata（非本土入侵物种）的竞争能力。本研究连续两年开展了两次温室试验：将来自3个种群的15个该禾草克隆株与Alliaria petiolata的莲座株种植于未被该入侵物种入侵过的原生森林土壤盆钵中。两个物种均会因对方的存在产生负向生长响应，其中Alliaria petiolata受到的抑制作用显著强于Calamagrostis porteri ssp. insperata。此外，该本土禾草的竞争效应取决于其种群来源，且在较小程度上取决于与入侵物种配对的单个克隆株。首次试验中的竞争效应强于次年重复试验。该禾草克隆株对试验结果的影响因种群、克隆株个体以及试验年份而异：来自3个种群中某一种群的克隆株，其影响作用显著强于另外两个种群的克隆株；15个克隆株中仅有1个，且该克隆株来自同一特定种群，在两次试验中均表现出显著影响。本研究佐证了日益增多的研究结论：优势物种克隆株间的种内变异可影响种间相互作用，且本土物种的此类变异可对入侵物种的生长表现产生显著影响。