Data from: Plant invasion overrides drought in suppressing arthropod abundance and richness

Plant invasions and drought are global change stressors that alter plant
availability and quality, habitat structure, and micro-site conditions,
with likely cascading effects on arthropod diversity, yet few studies have
disentangled their relative impacts. We quantified the effects of
experimental plant invasion (by Imperata cylindrica, cogongrass) and
simulated drought, imposed singly and in combination, on abundance and
morphospecies richness of arthropod communities, functional groups, and
individual taxa in regenerating longleaf pine understory located in humid,
subtropical central Florida, USA. Across all three scales of organization,
invasion emerged as a negative stressor, both alone and in combination
with drought, while drought alone had mostly positive effects on
arthropods. At the community scale, arthropod abundance and richness were
74% and 55% lower, respectively, in invaded than uninvaded plots
(averaging over drought) two years after initiation of invasion, while
drought had no negative effect. Herbivores, pollinators, and predators had
lower abundances (by 78%, 48%, and 73%, respectively) and richness (by
63%, 29%, and 67%) in invaded than uninvaded plots by the second year of
invasion. Herbivorous hemipterans, caterpillars, and beetles were more
negatively affected by invasion than grasshoppers, while for pollinators,
flies (rather than moths or bees) drove the negative response, exhibiting
lower abundance and richness when both stressors were present. There was
also a cascading negative effect of invasion on the abundances of
predatory wasps and spiders, and the richness of predatory wasps.
Conversely, several disparate taxa responded positively to drought without
invasion, despite significantly warmer and drier conditions under drought.
The pronounced negative effect of invasion on arthropod communities was
driven partly by its reduction of resident plant richness, which was in
turn positively correlated with arthropod abundances and richness. These
results suggest plant invasion as one important driver of arthropod
decline in a rapidly changing world.