Here in Alaska it is easy to take for granted our unspoiled natural surroundings. But there is a looming threat that many are becoming aware of that could affect our environment, a few of which are showing up in our communities.
A recent report by the USDA Forest Service finds that one of the four most important threats to our natural areas is the spread of invasive species. These eco-terrorists can be animals, insects, or microorganisms that may be an important part of a balanced ecosystem in their ancestral homeland but become aggressive invaders when transplanted outside their range.
In the spring of 2001, Phil Johnson, an employee of the Central Council of Tlingit and Haida, noticed a few plants growing outside his office building in downtown Juneau. Phil called local botanist Carol Biggs, who identified the plant as garlic mustard. Phil then contacted Dr. Barry Rice, an invasive plants specialist with The Nature Conservancy in Davis, Calif., who alerted Phil to the threat that the plants pose to local landscapes. Two years later, a group known as Juneau Invasive Plant Action, composed of concerned scientists and naturalists, continues working to eradicate this plant while we still have the chance.
Japanese knotweed forms colonies with dense growth of bamboo-like stems that exclude other vegetation. Many homeowners have planted it due to its rapid growth and ability to form a dense hedge. Many of those same homeowners have come to regret their decision because of its tendency to aggresively take over the entire yard. It does not respond to mowing and dumping the cut plants can serve to spread the plant, due to its ability to grow back from cut pieces of stem. Excavation and dumping of soil have spread it all over our communities. In Oregon and Washington, knotweed has become a serious concern because of its ability to grow in and around the streams that are spawning grounds for salmon and steelhead.
Those who fish and crab our waters should be on the lookout for a number of aquatic invasive species. The green crab is a voracious eater of clams, oysters, mussels, worms, urchins, other crabs, plants and fish. Males reach widths of about three inches. They have stronger claws than other crabs. Due to their small size, their use as human food is limited. Green Crabs appeared in San Francisco Bay in 1985. Their potential range stretches from Baja California to the Aleutians.
In the late 1980s salmon farmers in British Columbia began raising Atlantic salmon in pens. Many have escaped and sexually mature Atlantic salmon have been found in Alaska in both fresh and salt waters.
The spruce needle aphid has been here so long that most people don't realize it was introduced. Spruce aphid attacks can cause defoliation of spruce trees. Aphids are equipped with mouth parts that are designed to suck the sugar-rich sap coming out of the leaves in the phloem of the tree, causing the tree to shed its needles. Female aphids are able to reproduce without mating. Scientists joke that they are born pregnant. This allows their numbers to explode both rapidly and dramatically.
Today, there are 400 plant species considered to be serious threats to natural landscapes in the United States. For years, Alaska was considered immune from this threat due to its location and climate. However, biologists and others are becoming aware of some newcomers to our state. In fact we have an opportunity that other states lack, in that we have by far the most undisturbed landscape in the US, the smallest number of invasive species and the unique opportunity to keep them out before they become a problem.
We all know that management of natural resources can be a contentious issue, but invasive species should be a concern to all of us who care about our landscape. Invasive species could negatively affect our economy if they impinge on habitat of the fish and trees that support our timber, fish and tourism industries.
Contact the Alaska Department of Fish and Game for information on the European green crab, Atlantic salmon and other aquatic invasives. If you have a concern about an invasive plant, insect or other pest on your property or around town, contact Jim Douglas at University of Alaska Cooperative Extension Office in Juneau for help in identifying and treating insect pests and weeds. If you wish to help combat invasive plants in Southeast Alaska, contact Tom Heutte at (907) 586-8811 x 283.
Tom Heutte is a plant scientist with the USDA Forest Service, State and Private Forestry, Forest Health Protection Program in Juneau.