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 heatin...