Green, leafy invaders finding a home in Alaska

Submitted by Ned Rozell
Phone: 907-474-7648
03/17/08

With only five roads connecting it to the outside world, and a small number of airports and seaports, Alaska is more like an island than the peninsula it is. That isolation has helped save Alaska from the widespread invasion of non-native plants, but exotics are finding their way in.

In 1968, Eric Hulten documented about 175 exotic plant species in Alaska. During a 2006 count of Alaska plants, researchers came up with about 275 plants new to the state. Those plants have made it into the state as their seeds have hitchhiked in on vehicles and by other means. Alaskans have also imported non-native seeds in bales of hay and potted soil.

Jeff Conn has studied the latter two pathways for weeds to gain access into Alaska. He is a weed specialist with the USDA Agricultural Research Service who also is an affiliate faculty member at the University of Alaska Fairbanks. Conn, Casie Stockdale and Jennifer Morgan purchased bales of hay and straw from Alaska feed stores and then shook out the bales over screens. After seeds fell onto the screens, they planted them, and up popped 15 weed species not known to grow in Alaska, along with 17 types that already grow here. Because people spread hay and straw in horse corrals and dog yards--both places with disturbed soil and plenty of fertilizer--imported hay and straw bales could be significant vectors of alien plants in the Alaska countryside.

Why should anyone care about Alaska having more plants, especially some that result in pretty colors along our roadside from varieties such as the blue-flowered bird vetch or the purple loosestrife?

"You want to preserve an ecosystem the way it is," Conn said. "(Invasive species) can change the speed or direction of plant succession, they can compete with and eliminate other plants, and they can change fire frequencies (cheatgrass, a common invader in the west, flourishes and then dies in the same season, leaving behind a flammable understory)."

Along with testing for weeds in hay and straw bales, Conn and his coworkers also sieved the soil that comes with plants people buy at box stores and nurseries. Some were clean, but most soil had weed seeds. From the potted soil, the researchers germinated 54 plants different than those people thought they were buying from stores in Anchorage, Juneau and Fairbanks.

Alaska’s problem is small compared to other states. California, for example, had about 100 exotic plants in 1860, and 10 times that a century later.

"Alaska still doesn¹t have serious problems with invasive plants," said Trish Wurtz, an ecologist with the U.S. Forest Service in Fairbanks. "We’re still in the prevention mode, so there’s still a chance to do some good. We’re the only state in this situation."

How do you beat back the invaders, especially in these times of hyper commerce? Conn said awareness of the problem is important, and that Alaska’s isolation could work in its favor; inspectors could stop invasive weeds before they head into Alaska.

"We only have about 13 points of entry into the state," Conn said. "It should be feasible to prevent (exotic plants from coming through them.)"

Conn said once an exotic plant has spread to more than one acre, there’s no chance of eliminating the plant.

"I think of them as being like an oil spill," Conn said. "If you can prevent it from happening, it’s so much more cost-effective."

This column is provided as a public service by the Geophysical Institute, University of Alaska Fairbanks, in cooperation with the UAF research community. Ned Rozell is a science writer at the institute. To view past columns or to subscribe, visit www.gi.alaska.edu/ScienceForum/index.html .