Data from: Community disassembly and invasion of remnant native grasslands under fluctuating resource supply

1. Native vegetation fragments embedded in anthropogenic landscapes are
increasingly threatened by land-use intensification. Managing disturbance
regimes and nutrient inputs may help maintain species diversity in such
remnants. Yet it is unclear the extent to which changes in resource
availability due to reduced capture by resident plants and/or increased
supply rates may trigger native community disassembly and exotic
invasions. 2. We examined how mowing disturbance and N fertilizer addition
affected plant community recovery after a burning event in a remnant
corridor of tussock pampa grassland in Argentina. The percentage cover and
richness of native and exotic plant functional groups were monitored over
four years. According to the ‘fluctuating resource theory’, we expected
invasion to be highest when both light and N availability were increased
simultaneously. 3. Mowing delayed recovery by dominant C4 tussock grasses
and promoted subordinate, native C3 grasses and exotic legumes, thus
enhancing both native and exotic species richness. Fertilization induced a
transient increase in native forbs but decreased total plant richness.
Moreover, N addition to mowed grassland led to rapid invasion by
short-lived exotic forbs, which were then replaced by exotic perennial
grasses. Exotic grasses eventually spread across the grassland corridor,
although at different rates depending on the treatment, and in parallel to
a generalized decline in native species cover. 4. Synthesis and
applications. Community disassembly patterns reflected differential
responses of native and exotic functional groups to altered resource
supply rates. Synergisms between canopy disturbances and N enrichment
posed the greatest threat to preserving a pampa grassland remnant prone to
invasion. Establishing buffer zones may be required to enhance the
viability of corridor-like grassland remnants in agricultural landscapes.