Nonnative Invasive Plants in South Carolina: Combining Phase-2 with Phase-3 Vegetation Structure and Diversity Pilot Data to Enhance our Understanding of Forest Health Issues

Studies suggest that the Southeast is an area of primary concern with regards to the spread of alien plant species (Miller 2003, Stapanian and others 1998). Data collected by Stapanian and others in 1998 showed that Japanese honeysuckle (Lonicera japonica) occurred over 2 million acres in the Southeast, invading forests and displacing native species. Among the most important mechanisms for the early detection and prevention of the spread of nonnative species is monitoring on large spatial scales for the presence of alien species, and for the presence of vulnerable sites (in other words, sites affected by certain disturbance types) (Jose and others 2002). In the Southeast, a primary research priority is the need for better assessments of on-going biological invasion, for public and scientific use (Mack and others 2000). As one method for addressing this need, the Forest Service’s Forest Inventory and Analysis program incorporates assessments of the presence of nonnative species into its Phase-2 forest inventory. Additionally, pilot studies are currently underway for a new forest health variable that would describe native and alien vascular plant diversity and extent. This paper describes results gleaned from 2002 to 2004 Phase-2 data combined with 2002 Phase-3 vegetation structure and diversity pilot study data in South Carolina, USA. While small sample sizes limit the reliability of statistical tests for the pilot study, the results from the 2002 pilot illustrate potential uses for the new Phase-3 variable in monitoring and detecting the spread and impact of nonnative species in Southern forests.