Exotic Plant Monitoring in the Southern Plains Network, Project Report 2009

Folts-Zettner, Tomye; Bennetts, Robert; Sosinski, Heidi

Globalization of commerce, transportation, human migration, and recreation in recent history has introduced invasive exotic species to new areas at an unprecedented rate. For the National Park Service (NPS), the consequences of these invasions present a signifi cant challenge to the management of the agency’s natural resources “unimpaired for the enjoyment of future generations.” National parks, like other land-management organizations, are deluged by new exotic species arriving through predictable (e.g., road, trail, and riparian corridors), sudden (e.g., long-distance dispersal through cargo containers and air freight), and unexpected anthropogenic pathways (e.g., weed seeds in restoration planting mixes). Invasive exotic plants have been consistently ranked as a top vital sign for long-term monitoring as part of the NPS Inventory & Monitoring (I&M) Program. During fi nal selection of vital signs in 2006, invasive exotic-plant monitoring was recognized across all Southern Plains Network (SOPN) parks as the most important shared monitoring need. The strategy of early detection requires resource managers to: (1) detect invasive exotic species early (i.e., fi nd a new species or an incipient population of an existing species while the infestation is small—less than one hectare), and (2) respond rapidly (i.e., implement appropriate management techniques to eliminate the invasive plant and all of its associated regenerative material). As a complement to this strategy, the SOPN has incorporated the following objectives into its monitoring plan for exotic plants: (1) to detect the initial occurrence for any of a subset of high-priority species in areas of high and low invasion probability, (2) to determine changes in the status and trend (density, abundance or extent) of a subset of high-priority species in areas of high and low invasion probability, and (3) to determine changes in species composition of a subset of high-priority species in areas of high and low invasion probability, taking into account any management treatments that occurred between sampling intervals. In 2009, the SOPN conducted a pilot season for exotic-plant monitoring to test the methods and results of the network’s proposed Exotic Plant Monitoring Protocol. A total of 540 vector blocks (each 50 m long) were sampled along high-invasion-probability vectors (primary units) in SOPN parks. These vectors consisted of paved and unpaved roads and trails. As part of the SOPN grassland and fi re monitoring eff ort, a total of 360 individual 1-m2 plots on 72 transects in areas not considered high-invasion probability (secondary units) were also sampled. Overall, 60 species of exotic plants were observed in SOPN parks. Some species (e.g., Salsola tragus) were widespread among parks, whereas others were found in only a few parks. Results of the 2009 pilot study for each park sampled are presented in this report.

Exotic Plant Monitoring in the Southern Plains Network, Project Report 2009

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