Ruth Gronquist, a
wildlife biologist and Fairbanks District weed coordinator for the Bureau of
Land Management in Alaska,
educates the public about the threats invasive weeds pose to Alaska.
One of those invasive weeds, white sweet clover, is spreading above the Arctic
Circle and along Alaska’s 414-mile Dalton Highway,
in particular. This aggressive weed
propagates by dropping hundreds of thousands of seeds that remain viable in the
soil for decades. It eventually chokes
out native vegetation along highways, trails and rivers. In March 2008,
Gronquist gave the BLM-Alaska Resource Advisory Council an overview of BLM’s
weed-management strategy for the Dalton Highway Management Area. Afterward the council, a
citizen-based group that provides BLM with advice on public-lands management,
wanted to view the area firsthand. Five months later, Council
members took a fieldtrip to Coldfoot and the Dalton Highway
to see the impact of white sweet clover and bird vetch. The trip began near
Coldfoot Camp on the Dalton Highway above the
Arctic Circle. Gronquist and BLM intern Rehanon Nehus met
the council members at Rosie Creek,
just south of Coldfoot. BLM-Alaska State Director Tom Lonnie, Fairbanks
District Manager Bob Schneider and other BLMers also joined them at the
site. There, 250 miles north of Fairbanks,
began a morning of invasive-weed education and weed pulling. The group donned
safety vests for visibility and knee pads for protection and then went to work
pulling weeds. The work crew filled eight large trash bags with approximately
480 pounds of white sweet clover and bird vetch. Gronquist explained that
instead of dumping the weeds in a landfill, the crew burns the bags and
contents. White sweet clover
grows in the soft shoulders of the highway where traffic and wind carry seeds
to new areas. The clover now grows as far north as Coldfoot. Gronquist is
concerned that the clover will soon take hold on stream banks where currently
no invasive plants exist. Just like the
clover that grows in suburban lawns, white sweet clover alters the nitrogen level in the soil, making it
unfit for some plants to populate. But unlike the lawn variety that
grows as small plants close to the ground, white sweet clover can grow several
feet tall in just a couple of years. Its
stem and root ball resemble the size of an adult’s wrist and fist, and each
mature plant produces thousands of seeds.
Alaska’s
wild animals do not eat white sweet clover, which is moderately toxic to
animals if they ingest it. White sweet clover
is a biennial plant; so eliminating the first-year plants before flowering is
the best time to attack the problem.
Although labor intensive, hand weeding is currently the most effective
solution because the white sweet clover is still contained along the shoulders
of the Dalton
Highway. Removing second-year plants, taproot and all,
before they go to seed is also highly effective. Concern for the
future is that white sweet clover and other invasive plants will choke out the
indigenous vegetation. Their sheer
numbers and ability to alter soil moisture and chemistry will shade out native
plants or inhibit germination. Combine
the rapid growth and spread rate of invasive weeds with a warming climate, and
problems could lie ahead for the Alaska’s arctic and boreal
ecosystems. Gronquist will
return to the field-trip site this summer to monitor and study the
effectiveness of the weed-pulling efforts.
This hands-on expedition gave the council members a better understanding
of this important program and the challenges BLM-Alaska faces as it manages
public lands in the Arctic. For more
information about BLM-Alaska’s invasive weed programs, visit the Web site: http://www.blm.gov/ak/st/en/prog/noxweeds.html.
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