Data from: Soil microbes mediate the effects of resource variability on plant invasion

A fundamental question in ecology is which species will prevail over
others amid changes in both environmental mean conditions and their
variability. Although the widely accepted fluctuating resource hypothesis
predicts that increases in mean resource availability and variability
therein will promote non-native plant invasion, it remains unclear to what
extent these effects might be mediated by soil microbes. We grew eight
invasive non-native plant species as target plants in pot-mesocosms
planted with five different synthetic native communities as competitors
and assigned them to eight combinations of two nutrient-fluctuation
(constant vs pulsed), two nutrient-availability (low vs high) and two
soil-microbe (living vs sterilized) treatments. We found that when plants
grew in sterilized soil, nutrient fluctuation promoted the dominance of
non-native plants under overall low nutrient availability, whereas the
nutrient fluctuation had minimal effect under high nutrient availability.
In contrast, when plants grew in living soil, nutrient fluctuation
promoted the dominance of non-native plants under high nutrient
availability rather than under low nutrient availability. Analysis of the
soil microbial community suggests that this might reflect that nutrient
fluctuation strongly increased the relative abundance of the most dominant
pathogenic fungal family or genus under high nutrient availability, while
decreasing it under low nutrient availability. Our findings are the first
to indicate that besides its direct effect, environmental variability
could also indirectly affect plant invasion via changes in soil microbial
communities.