Exotic Plant Inventories in Mount Rainier, North Cascades, and Olympic National Parks tabular data

Exotic plant inventory in Mount Rainier, North Cascades, and Olympic National Parks 2001-2002 tabular data.

We focused our survey on habitats most susceptible to exotic plant invasion within the three parks. Susceptible habitats were defined as areas that provided both good substrates for exotic plant establishment and where there was a high probability of exotic seed dispersal. Using this definition, we identified four habitats for surveys: roads, trails, riparian areas (i.e., rivers), and developed zones.

The objectives for these inventories were to: 1) document exotic plant species that occur in susceptible habitats in each park, 2) describe distribution and abundance patterns of exotic plant species across vulnerable habitats, 3) identify habitats with the greatest exotic species richness, 4) identify patterns of exotic species richness with respect to elevation and distance from trailhead, and 5) identify priority exotic species for control based on biologic and management considerations. 

We utilized a two stage sampling design. The first stage or strata was composed of the four sensitive habitats: roads, trails, riparian areas and developed zones. All four habitat types were identified in GIS. Within our four habitats, we included all developed zones on park owned land (i.e., no privately owned lands), all roads, all park maintained trails (i.e., no social or informal trails), and riparian areas with a slope ≤ 8% (safe access for field crews). Roads, trails, and riparian areas were considered to be linear features and were divided into segments along which subsamples (i.e., plots) were distributed. All segments were ≤ 5 miles in length and we generally utilized junctions with other trails, roads, or rivers to identify segments so that the segments could easily be identified in the field. Roads and trails had a minimum segment length of 0.5 miles and riparian areas had a minimum length of 1.0 miles. Segments were numbered within each strata and then randomly selected for sampling. After a random placement of the first plot within the first 0.5 miles of the randomly selected segment, plots were systematically distributed every mile within the road, trail, and riparian segments which had been randomly selected.

All plots or subsamples covered an area of 100 m2 however, the dimensions and distribution of the plots varied depending on habitat type. Road and trail plots were 1m x 100 m and were established parallel to the road or trail. The first plot was located on the right or left side of the trail based on a coin toss and successive plots alternated sides. Riparian plots were also 100 m2, but plot dimensions varied based on the terrain in order to locate the entire plot within the riparian zone. Crew members determined the plot dimensions when they arrived at the plot location. Frequently, plots were square (i.e., 10m x 10m), but when rectangular plots were used, they were oriented perpendicular to the river to capture variation in plant distribution within the riparian area. Developed zone plots were 10m x 10 m and were located relative to a random location generated in the GIS. 

We surveyed 697 plots across the three parks and documented 112 exotic species in 348 (~50%) of the plots. We documented 42 species in MORA, 64 at NOCA, and 81 in OLYM. At all three parks, exotic species richness was generally highest in plots located in roadsides or developed zones. Our study documented 8 species that were not on the parks’ comprehensive online species lists (NPSpecies 2016): 2 at MORA and 6 at OLYM. Although we did not document any new species at NOCA, our study provided previously unavailable abundance information for that park.

Tags: biota, ecological-framework-biological-integrity-invasive-species-invasive-exotic-plants, environment, exotic, invasive, inventory, inventory-and-monitoring-program, mora, mount-rainier-national-park, nccn, noca, non-native, north-cascades-natioanl-park, north-coast-and-cascades-network, nps, olym, olympic-national-park, plants, resource-management, vascular-plant, vegetation
Organization: Department of the Interior