Post-fire invasion risk of Chinese tallow(Triadica sebifera)in a slash pine flatwood ecosystem in the Gulf of Mexico Coastal Plain,United States:mechanisms and contributing factors at the community level

The invasion of Chinese tallow(Triadica sebifera(L.)Small)is a serious threat to the endangered slash pine(Pinus elliottii)flatwood ecosystem in the Gulf of Mexico Coastal Plain,United States.Prescribed fire in combination with vegetation management has been suggested as a preferred approach for mitigating Chinese tallow invasion and restoring this endangered ecosystem.A large plot of 0.86-ha with 281 nested contiguous 30-m^(2) quadrats was established in a tallow-invaded slash pine flatwood and all tallow trees,saplings,seedlings and associated factors in each quadrat were measured to study the community-level tallow invasion processes before and after a prescribed fire and by dispersal and community factors.Classification and regression tree models show that the dispersal factors(distances to the road and to the trail)and microtopography(elevation)determine the invasion probability of tallow,but the degree of invasion(abundance)of tallow depends on the interactions of both dispersal factors and community factors such as canopy closure and grass/herbaceous coverage.Areas nearer to roads and trails,dominated by native grass/herbaceous species,and with a low elevation and canopy closure are highly susceptible to tallow invasion and establishment.The effect of fire on tallow invasion varies with overstory and understory conditions.Density of tallow seedlings and saplings increased greatly after fire in the areas dominated by slash pines in the overstory and native grass/herbaceous species in the understory.To control tallow invasion and establishment,tallow seed trees/sources should be removed from the area and vicinity to be burned.