INVASIVE PLANT MANAGEMENT PLANNING IN NATIONAL PARKS can be categorized in three stages: inventory/survey, monitoring, and management (Rew et al. 2006). Inventories or surveys document the presence and may roughly describe the relative abundance of invasive plants in natural areas. The flexibility and broad spatial extent associated with inventories are often required for effective early detection of small invasive plant populations (Carpenter et al. 2002). Monitoring, by contrast, provides unbiased, statistically powerful, and cost-effective approaches to detect change in invasive plant abundance or distribution (Gibbs et al. 1998). While inventories often focus on extensive spatial scales, monitoring focuses only as broadly as necessary to provide reasonably precise variable estimates given the expected spatiotemporal variability. Inventories and monitoring are intended to plan or assess invasive plant management.
A comprehensive map of invasive plants occupying a national park would fully meet inventory and monitoring needs. From a monitoring standpoint, maps with reasonably small minimum mapping units reproduced accurately over time would detect changes in the abundance and spread of invasive plants. Combined with information on the controls applied to specific groups of invasive plants, maps could also be used to assess management effectiveness. Widespread interest in weed mapping reflects the potential benefit of such maps and the availability of global positioning system (GPS) technology (NAWMA 2002).
Despite notable advantages, comprehensive mapping of invasive plants in national parks poses several challenges. Mapping with small minimum units can often be accomplished only over small areas. As map unit size increases, mapping becomes more efficient, but increases the difficulty of detecting change in perimeters and presumably increases error in plant detection and estimation of abundance within the perimeter. Furthermore, comprehensively mapping invasive plants on a large landscape is generally cost-prohibitive (Stohlgren 2007). With this challenge in mind, we developed and tested a simple, rapid survey method intended to simultaneously inventory, monitor, and map invasive plants in national parks with a cultural resource focus (Young et al. 2007).
Young, C. C., and J. L. Haack. 2009. Research Report: A rapid, invasive plant survey method for national park units with a cultural resource focus. Park Science 26(2):70–75.
Available at http://www.nature.nps.gov/ParkScience/archive/PDF/Article_PDFs/ParkScience26(2)Fall2009_70-75_YoungHaack_2660.pdf.