Since the 1920s spotted knapweed (Centaurea maculosa) has adapted to a variety of
habitats, including pastureland, rangeland, hay land, open forests, road sides, and ditches.
In 2003 this plant species dominated more than five million acres in Montana, half of the
total infestation of noxious weeds in the state.
This project demonstrates the utility of using downscaled Parameter-elevation
Regressions on Independent Slopes Model (PRISM) data for predicting vegetation
movement within a 2°×2° geographical area surrounding Missoula County, Montana.
This localized climate change data was correlated against current knapweed range using
validation data from the Volunteer for Wilderness Program at the Wilderness Institute at
The University of Montana and the County of Missoula Weed District to examine
optimal climatic conditions within the area. Parameters for precipitation and temperature
were determined from current locations of spotted knapweed. These relationships were
then used, with existing future climate scenarios from the Intergovernmental Panel on
Climate Change (IPCC) and the United States Global-change Research Program
(USGCRP), to predict the extent of knapweed based on its environmental tolerance
ranges.
The potential expansion of suitable habitat for spotted knapweed within the study area
was significant with minimal increases in temperature and precipitation, but the longterm
effects of possible increases of 4.5°C and up to 10 cm of precipitation would cause a
contraction of suitable habitat for spotted knapweed. Further studies on tolerance ranges
would increase the understanding of potential invasive species movement and climate
change.
