WWETAC Projects

Project Title: Mapping of invasive plant spread on roads and river networks in Alaska

Principal Investigator: Matt J. Macander, ABR Inc. Fairbanks, Alaska


Tricia L. Wurtz, PNW Research Station, USDA Forest Service; Brian Hay, University of Alaska Fairbanks; Chris Swingley, ABR Inc.

Key Issues/Problems Addressed:

The number of invasive plant species in Alaska increase each year. Public lands are vulnerable to invasion through proximity to roads and rivers. Non-native Melilotus alba, or sweet clover, is one of the most widely distributed invasive plants in Alaska, and has invaded flood plains of at least three glacial rivers from upstream roadsides and colonized natural habitats.

Setting and Approach:

A network model was developed to elucidate spatial relationships between roads, river crossings and downstream public lands of high conservation significance. In 2005 and 2006 the distribution of M. alba was documented in interior and south-central Alaska. GIS data layers were developed and compiled into summary tables which can be queried to extract specific information for a management unit.

Key Findings:

Of the ten major crossings that were surveyed in road corridors leading to Kanuti National Wildlife Refuge, none had M. albas in the natural floodplain either upstream or downstream of the crossing. Six of the ten crossings had M. alba on the roadside immediately adjacent to the crossing, but the plants had not spread further. Five of the crossings were characterized as moderately or highly vulnerable to invasion by M. alba. Using the distribution data and the network model, we compiled a report listing all of the crossings upstream for each of the 98 conservation units in the study area. The network model proved to be a valuable approach and provides key information to land managers, transportation managers, and groups planning to conduct surveys of invasive plant distribution.


A GIS approach was developed that elucidates the relationship between lands of high conservation value, and roads and rivers that have the potential for corridors for invasive plants.


Wurtz, T.L., Macander, M.J., and Spellman, B.T. 2010. Spread of invasive plants from roads to river systems in Alaska: A network model. Pages 699-708 in Pye, John M.; Rauscher, H. Michael; Sands, Yasmeen; Lee, Danny C.; Beatty, Jerome S., technical editors. 2010. Advances in threat assessment and their application to forest and rangeland management. USDA Forest Service General Technical Report PNW-GTR-802 Volume 2, Portland, OR (PDF, 524 KB)

WWETAC Project ID: FY07BK23