||Non-native invasive species have significantly changed the composition and ecosystem
function of many North American landscapes. Currently, invasive species are recognized
as the second greatest destroyer of biological diversity, superseded only by direct
habitat destruction and consequent fragmentation from human development. Glacier
National Park, an international Biosphere Reserve and World Heritage Site, is threatened
by the encroachment of numerous noxious non-native invasive plant species. Prevention,
early detection, and immediate action against invasive weed species in their initial
establishment phases are paramount in reducing this threat.
To facilitate strategic management actions, this study developed two maximum entropy
invasive species distribution models for Glacier National Park. The first model
was based entirely on environment variables associated with habitat, while the second
model added environmental variables associated with vectors of spread to the environmental
variables associated with habitat. The rationale behind the nested model approach
was to determine invasion potential based on high quality invasive species habitat
followed by invasion potential based on vectors of spread (keeping the relative influence
of habitat constant). The two model results were then overlain to evaluate which
areas were most susceptible to establishment of invasive species, the spatial distribution
of these areas, and the locations with maximum potential for tactical management to
prevent further invasive species spread. The analysis produced 10 nested species
distribution model sets: a set for each of the 9 virulent priority invasive species
individually and a set for all invasive species combined.
For all invasive plant species combined, it was found that 30,928 acres (7.6%) of
Glacier National Park had high quality invasive species habitat but lower invasion
potential, 6,071 acres (1.5%) had high invasion potential but lower quality habitat,
and 20,648 hectares (5.1%) had both high potential for invasion and high quality habitat.
The latter was considered the area at greatest risk of invasion. The most influential
vectors of spread were roads and trails, and the most important environmental factors
were elevation, alluvial soils, slope, and forest land cover. Together, these findings
and their spatial distributions allow Glacier National Park to prioritize invasive
species monitoring, prevention and treatment.