Invasive plants have greater growth than co-occurring natives in live soil subjected to a drought-rewetting treatment

Although several studies indicate that invasive plant species respond more negatively to drought than native plant species, little remains understood of how and whether drought-rewetting events may affect growth of invasive and co-occurring native plant species both directly and indirectly through soil microorganisms. In a fully crossed factorial design, we grew individuals of four congeneric pairs of invasive and native plant species in 2.5 L pots that contained live or sterilized field soil under one of three drought treatments: no-drought, drought, drought-rewetting. Results show that drought caused a significantly greater decline in total biomass of invasive plants than that of native plants regardless of the presence of live soil microorganisms. However, total biomass of the invasive plants exhibited a greater recovery from drought following rewetting than did that of the native plant species. Moreover, the recovery from drought in invasive species tended to be stronger in live soil than in sterilized soil, while for the native plants, recovery from drought was stronger in sterilized soil than in live soil. Overall, these results suggest that soil biota may enable invasive plants to grow larger than co-occurring native plant species in ecosystems that experience cycles of drought and rewetting.

Methods
In a fully crossed factorial design, we grew individuals of four congeneric pairs of invasive and native plant species in 2.5 L pots that contained live or sterilized field soil under one of three drought treatments: no-drought, drought, drought-rewetting. We collected data from this control experiment.