Spatiotemporal Analysis of Three Common Wetland Invasive Plant Species Using Herbarium Specimens and Geographic Information Systems


Ryan J. Miller

Additional Authors:

Andrew D. Carroll, Thomas P. Wilson, Joey Shaw


June 2009


ABSTRACT The negative ecological impact of invasive plant species has been widely reported in recent years. Herbarium specimens can allow for the study of spatiotemporal spread of invasive species in order to understand distribution characteristics and patterns which can then be utilized for management decisions. In this study, three common wetland invasive plant species (Phragmites australis, Lythrum salicaria and Rorippa nasturtium-aquaticum) were chosen and analyzed via two previously published methods to determine the historic rate and pattern of spread as well as to identify periods of invasiveness. Performance of these methods varied in scale with a general, area-corrected approach covering the entire southeastern United States and an associate species-corrected method covering smaller, regional areas of dense historical specimen collection. Results showed positive spread over time for these three species in both methods; however, periods of invasiveness did not coincide between the two methods. The use of two different methods and the subsequent comparison of results show the importance of sampling bias correction, scale selection, and adequate sample sizes for spatiotemporal analyses of plant distributions using herbarium records.