Predicting the post-fire establishment and persistence of an invasive tree species across a complex landscape

The reintroduction of pre-European fire regimes has allowed the entry of many invasive plant species into fire-dependant ecosystems of North America. However, the environmental factors that favor the post-fire establishment of these species across complex landscapes are not well understood and the initial establishment of invasive species does not necessarily result in long-term persistence. To evaluate the post-fire establishment and persistence of disturbance-dependent invasive plants, we studied the invasion of Paulownia tomentosa (princess tree, an early-successional species introduced from Asia) across three burns in the southern Appalachian Mountains. Based upon classification tree analysis, the presence/absence of P. tomentosa 2 years after burning was most strongly related to the cover of residual vegetation, topographic shading, and moisture availability. Spatial application of classification tree models to repeated survey data showed that P. tomentosa established across a wide range of microsites 2 years after burning. However, predicted habitat for P. tomentosa decreased by 63% 4 years after fire and by 73% 6 years after fire. Following its initial widespread establishment, P. tomentosa only persisted on xeric and exposed topographic positions that experienced high intensity burning. However, the sites where it persisted include rare community types that contain two endangered plant species that depend upon fire for successful reproduction. The control of P. tomentosa on these ecologically important sites may require special attention from land managers.