Fire management in a post-invasion landscape: Establishment and persistence of Paulownia tomentosa in the southern Appalachians

Background/Question/Methods

Over the past decade, prescribed burning has been increasingly used to reintroduce native fire regimes and restore fire-dependent communities.  However, in contemporary landscapes the reintroduction of fire often brings unintended consequences, such as the invasion of exotic species.  In the southern Appalachians, Paulownia tomentosa, an early successional species introduced from Asia, invades aggressively following both wild and prescribed fire.  In Great Smoky Mountains National Park, considerable time and funding have been expended controlling this and other species following fire.  Assessing the threat posed by species such as Paulownia tomentosa requires answers to two questions: (1) Where across the landscape is post-fire invasion most likely to occur? (2)  Is the species able to persist and compete with native vegetation during post-fire succession?  To address these questions, we sampled vegetation in 5 burns distributed across the southern Appalachians. 

Results/Conclusions

Our results show that Paulownia tomentosa invades most heavily on severely burned dry ridges and steep slopes where post-fire vegetation cover is less than 44%.  Further, from seed bank and seedling distribution studies we determined that this species may invade up to 10 km from adult trees.  However, according to our results this species is a poor competitor during post-fire succession and is not likely to persist in most pine and oak-pine forests.  Long-term persistence of this species is most likely to occur on more xeric and exposed sites such as rock outcrops and cliff lines.  Our findings suggest that control efforts may be best focused on these extreme habitats where Paulownia tomentosa is most likely to persist and compete with native species.