Another roadside detraction

by Joshua Zaffos

Next time you’re cruising the open highway or ambling along a backwoods two-track, be wary of hitchhikers with barbed seedlings and spiky thistles. New studies from the University of California, Davis show that roads significantly promote the spread of invasive weeds.

Noxious weeds such as cheatgrass, leafy spurge and knapweed already occupy over 133 million acres nationwide. Weeds displace native plant species, increase fire risk and destroy wildlife habitat and rangeland forage — and they’re continuing their invasion at a rate of 1.7 million acres a year.

The UC Davis studies, authored by doctoral student Jonathan Gelbard, environmental science professor Susan Harrison and U.S. Geological Survey ecologist Jayne Belnap, say the invasion is accelerating. Roads are a major reason: They create avenues where weeds, hitching rides off radiator grilles and gusts from passing vehicles, can penetrate and alter ecosystems. The new studies provide fodder for advocates of planned rural development, and offer yet another reason for the protection of public roadless lands.

For a copy of the report, contact Jayne Belnap at 435-719-2333 or jayne_belnap@usgs.gov. © High Country News