Data and code from: Invasive grass indirectly alters seasonal patterns in seed predation

Invasive species threaten ecosystems globally, but their impacts can be
cryptic when they occur indirectly. Invader phenology can also differ from
that of native species, potentially causing seasonality in invader
impacts. Yet, it is unclear if invader phenology can drive seasonal
patterns in indirect effects. We used a field experiment to test if an
invasive grass (Imperata cylindrica) caused seasonal indirect effects by
altering rodent foraging and seed predation patterns through time. Using
seeds from native longleaf pine (Pinus palustris), we found seed predation
was 25% greater, on average, in invaded than control plots, but this
effect varied by season. Seed predation was 24% - 157% greater in invaded
plots during spring and fall months, but invasion had no effect on seed
predation in other months. One of the largest effects occurred in October
when longleaf pine seeds are dispersed, suggesting potential effects on
tree regeneration. Thus, seasonal patterns in indirect effects from
invaders may cause underappreciated impacts on ecological communities.