Data from: Past tree influence and prescribed fire mediate biotic interactions and community reassembly in a grassland-restoration experiment

Woody plant encroachment of grasslands is occurring globally, with
profound ecological consequences. Attempts to restore herbaceous dominance
may fail if the woody state is resilient or if intervention leads to an
alternate, undesirable state. Restoration outcomes often hinge on biotic
interactions – particularly on priority effects that inhibit or promote
community reassembly. Following experimental tree removal from
conifer-invaded grasslands, we documented substantial variation in
community reassembly associated with the changing abundance of the native
clonal sedge Carex inops L.H. Bailey subsp. inops. We explored possible
mechanisms for this variation, focusing on the nature and timing of
interactions between the meadow community and Carex and on how past tree
influence and prescribed fire mediate the outcomes of these interactions.
Meadow species increased after tree removal, but less so in burned than in
unburned plots. Carex expanded dramatically after fire, particularly where
past tree influence had been greater. Meadow species and Carex developed
an increasingly negative association over time; pre-emption was
reciprocal, but offset in time and space. Meadow species inhibited Carex
through vegetative recovery in areas of limited or recent tree influence,
irrespective of fire. Carex inhibited meadow reassembly in areas of
greater tree influence, but only with burning. Synthesis and applications.
Tree removal and fire imposed across a range of altered meadow states
yielded varying outcomes, reflecting biotic interactions and species'
regenerative traits that inhibited or promoted reassembly. Fire tended to
destabilize the remnant meadow community and, in areas more degraded by
encroachment, stimulated release of Carex, which inhibited reassembly.
Knowledge of the context dependence of biotic interactions can enhance the
effectiveness of restoration by establishing the bounds within which
treatments produce desirable or undesirable outcomes.