Presentation Type

Presentation

Faculty Mentor’s Full Name

Ben Colman

Faculty Mentor’s Department

Aquatic Ecosystem Ecology

Abstract

Disturbances such as fire, grazing, land clearing, and flooding are important in determining the diversity and composition of plant communities. While disturbance can help maintain this diversity, it can also open up niches that fast growing nonnative plants can exploit, including noxious weeds that displace native plants and degrade habitat quality for wildlife. Controlling noxious weeds is a top priority for land managers, but can be challenging without relevant data on the location, areal extent, and intensity of infestations. One approach for providing such information is to conduct a weed inventory by mapping infestations present. For this project we have partnered with Five Valleys Land Trust to examine changes in noxious weeds over five years at the 300-acre Rock Creek Confluence (RCC) property outside of Clinton, MT. This site was subject to over a century’s worth of grazing and was more recently disturbed by the early stages of subdivision development. It is now infested with numerous noxious weed species. We inventoried seven noxious species that were of highest concern to managers utilizing ArcGIS field recorders to detail infestation characteristics. The seven invasive species inventoried include: oxeye daisy, dalmatian toadflax, leafy spurge, spotted knapweed, common tansy, perennial pepperweed, and hoary alyssum. Over the five years there was a 7% decrease in overall weed acreage. The species with greatest areal extent were spotted knapweed, leafy spurge, and common tansy. Two out of the three species (spotted knapweed and leafy spurge) both decreased in acreage by 15% over five years, and are thus responsible for the majority of the net weed reduction. The small decreases in acreage invaded for some species suggests that the weed treatments at the RCC property may be slowing if not reversing the spread of the most ubiquitous invaders.

Category

Life Sciences

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A Decline in Areal Extent of Noxious Weeds at the Rock Creek Confluence Site in Clinton, MT

Disturbances such as fire, grazing, land clearing, and flooding are important in determining the diversity and composition of plant communities. While disturbance can help maintain this diversity, it can also open up niches that fast growing nonnative plants can exploit, including noxious weeds that displace native plants and degrade habitat quality for wildlife. Controlling noxious weeds is a top priority for land managers, but can be challenging without relevant data on the location, areal extent, and intensity of infestations. One approach for providing such information is to conduct a weed inventory by mapping infestations present. For this project we have partnered with Five Valleys Land Trust to examine changes in noxious weeds over five years at the 300-acre Rock Creek Confluence (RCC) property outside of Clinton, MT. This site was subject to over a century’s worth of grazing and was more recently disturbed by the early stages of subdivision development. It is now infested with numerous noxious weed species. We inventoried seven noxious species that were of highest concern to managers utilizing ArcGIS field recorders to detail infestation characteristics. The seven invasive species inventoried include: oxeye daisy, dalmatian toadflax, leafy spurge, spotted knapweed, common tansy, perennial pepperweed, and hoary alyssum. Over the five years there was a 7% decrease in overall weed acreage. The species with greatest areal extent were spotted knapweed, leafy spurge, and common tansy. Two out of the three species (spotted knapweed and leafy spurge) both decreased in acreage by 15% over five years, and are thus responsible for the majority of the net weed reduction. The small decreases in acreage invaded for some species suggests that the weed treatments at the RCC property may be slowing if not reversing the spread of the most ubiquitous invaders.