Data from: Soil mesofauna may buffer the negative effects of drought on alien plant invasion

Although many studies have tested the direct effects of drought on alien
plant invasion, less is known about whether drought affects alien plant
invasion indirectly via interactions of plants with other groups of
organisms such as soil mesofauna. To test for such indirect effects, we
grew single plants of nine naturalized alien target species in
pot-mesocosms with a community of five native grassland species under four
combinations of two drought (well-watered vs drought) and two
soil-mesofauna-inoculation (with vs without) treatments. We found that
drought decreased the absolute and the relative biomass production of the
alien plants, and thus reduced their competitive strength in the native
community. Drought also decreased the abundance of soil mesofauna,
particularly soil mites, but did not affect the abundance and richness of
soil herbivores. Soil-fauna inoculation did not affect biomass of the
alien plants but increased biomass of the native plant community, and
thereby decreased the relative biomass production of the alien plants.
This increased invasion resistance due to soil fauna, however, tended (p =
0.09) to be stronger for plants growing under well-watered conditions than
under drought. Synthesis. Our multispecies experiment thus shows that soil
fauna might help native communities to resist alien plant invasions, but
that this effect might be weakened under drought. In other words, soil
mesofauna may buffer the negative effects of drought on alien plant
invasions.