Data from: Invasive grass fuel loads suppress native species by increasing fire intensity and soil heating

Non-native invasive grasses are driving intense fires across the globe but
the impacts of native versus invader-fueled fires on community assemblages
are poorly understood. By increasing fire intensity, grass invasions might
increase belowground mortality of heat-sensitive seeds and buds, thereby
shifting community composition. We compared fuel loads in native and
non-native invasive (cogongrass, Imperata cylindrica) plant dominated
areas of pine savannas in Florida. Then, we conducted a field experiment
to examine how fuel loads and native and invasive fuel types affected soil
heating and seedling emergence or resprouting of native and invasive plant
species. We found that average fuel loads in invaded communities
were greater than in native communities and that soil heating,
including heating duration >60 °C, maximum temperature, and heat
flux >60 ºC, increased, and seedling emergence and resprouting
decreased with greater fuel loads. These relationship between
soil heating and fuel loads did not differ between
the overlapping range of native and invasive fuel loads,
but longer durations of soil heating at the higher average fuel
loads of invaded communities resulted in 23% lower predicted probability
of seedling emergence compared to average fuel loads of native
communities. Resporuting of cogognrass, the invader responsible for fuel
loading, was unaffected by soil heating.  By increasing fuel
loading and soil heating, grass invasions may alter post-fire community
assemblages and facilitate invasive grass dominance at the expense of
native species via an invasion-fire cycle. Fuel loads can be used to
predict soil heating duration and depth and these data, combined with
information on species tolerances to heating, can be used to forecast
impacts of invasions on post-fire community composition. To maintain fire
regimes that promote native communities and resist invader dominance, it
is critical to manage invasive species that increase fuel loads.