Invasive Plants: Guide to Identification and the Impacts and Control of Common North American Species. This book serves as both a field guide and a good introduction to the environmental and economic issues raised by invasive species in natural areas.
Part I tells the history of invasives and describes means developed and developing for managing them.
Chapter 1. The Aliens Landed Logn Ago and Keep arriving
Chapter 2. Invasives Changing Wild America
Chapter 3. Managing the Good, the Bad, and the Ugly
Chapter 4. A quick Key to Identifying Major Species of Invasive Plant Groups
Part II is an extensive guide to species with color photos of the best identifying features and the story of how the plant arrived and what it does in the environment.
INTRODUCTION: The Invasive Species Challenge
Nothing unites a country like an invasion, and the war against invasive species has created rare common ground for forest owners, homeowners, farmers, ranchers, liberal environmentalists, and free market environmentalists.
Agriculture Undersecretary Mark Rey called invasive species the most underappreciated problem affecting national forests.
In a well publicized and often quoted speech before the Izaak Walton League in July 2003, U.S. Forest Service Chief Dale Boswell asked the nation to appreciate the latest greatest environmental threat to its forests. “The second great threat [after fire],” Bosworth said, “is the spread of unwanted invasive species. . . .Nationwide, invasive plants now cover an area larger than the entire Northeast, from Pennsylvania to Maine. Each year, they gobble up an area larger than the state of Delaware. . . . All invasives combined cost Americans about $138 billion per year in total economic damages and associated control costs.” Bosworth also cited studies that estimate invasives “have contributed to the decline of almost half of all imperiled species.”
In the literature of environmental groups, the alert has a familiar doomsday ring: “An invasion is under way that is undermining our economy and endangering our most precious natural treasures.” (NatureServe)
Environmental groups first began to coalesce around this issue in the late 1990s. Representatives of groups that fund environmental programs, meeting as the Consultative Group on Biological Diversity in 1999, commissioned a review of the invasive species threat that linked the issue to both economics and biodiversity.
Among the groups that have made invasives a top priority are Defenders of Wildlife, the Union of Concerned Scientists, The Nature Conservancy, World Resources Institute, Conservation International, the Wilderness Society, the environmental Defense Fund, Natural Resources Defense Council, Sierra Club, and Audubon Society. The federal government's role is guided by an interagency National Invasive Species Council created in February 1999 when President Clinton issued Executive Order 13112 (http:\\www.invasivespecies.gov)
As the invasive species issue moves onto center stage, it brings with it a cast that demands new laws, regulations and funding. The National Forest Foundation estimates, “Each year, the U.S. spends $13 billion per fighting noxious weeds . . .” (National Forest Foundation). California estimates the cost of eradicating the red fire ant could run to almost $1 billion in that state alone (Jenner). And fire ants, compared to fungi, flying insects and self-pollinating plants are relatively easy targets. Dr. Jim Tate, Science Advisor to Secretary of the Interior Gale Norton, told Congress in 2003, “Invasive plants alone are estimated to cause more than $20 billion per year in economic damage. “ (USDA 2003)
Speaking for the president in October 2003 and announcing $1.5 million in grants to universities in eight states, Agriculture Secretary Ann Veneman said, “Protection of the nation’s agriculture and natural resources from invasive pests is a top priority for the Bush Administration.” (USDA Release No. 0349.03, 22 Oct 2003).
In 2005 an interagency task force of federal government scientists issued a report whose alarm was as intense as that of any environmental group. Its executive summary began, “America is under siege by invasive species of plants and animals, and by diseases. The current environmental, economic, and health-related costs of invasive species could exceed $138 billion per year—more than all other natural disasters combined.” (USGS, 2004)
This is the kind of language used to underline the huge size of assets at risk and thus to justify large public programs and expenditures. Even before the Bush administration signed on, total federal spending to fight invasive species had risen to some $600 million in fiscal year 2000 (Tate, October 2002). Spending by the Animal and Plant Health Inspection Service (APHIS) has risen from some $556 million in FY 2000 to $987 million in the 2005 USDA budget.
Environmental groups are calling for much more.
In 2001 The Nature Conservancy, assessing its own problems and proposing to spend $10 million in research, noted $137 billion in costs and a federal budget for fighting invasives of only $630 million. This is about 0.4% of the estimated costs. (Nature Conservancy, 2001) A Nature Conservancy task force in 2001 recommended that TNC, “Elevate the political profile of the invasive alien species issue to establish new funding and policy support for invasive species management in the U.S. and internationally.” (Nature Conservancy, 2001) The Union of Concerned Scientists credits itself with rallying more than 300 experts on invasives to its “Sound Science Initiative.” (UCS, 2001)
The Nature Conservancy, owning hundreds of thousands of acres of its own lands, began working on invasive species in the late 1980s, but farms, forests, highway departments, parks, and homeowners have been fighting invasive species for over a century. Farm stores and the garden section of every department store have offered a variety of remedies to attack invasive species from herbicides to traps and bullets. Individual species like the snakehead fish, sudden oak death and giant hogweed have sometimes made national news.
In 2003 the government agencies joined environmentalists, greatly expanding its presence in an increasingly popular war against invasives in general. Why has this old, ever simmering guerilla war suddenly become a major battlefront for the environmental movement?
First, the problem is real, it is big, and it is both an economic issue and an environmental issue. Since the advent of European settlement in North America over 50,000 species of plants alone have been introduced. While many enhance our landscaping and others provide 98% of our crops, some 5,000 have gone wild to compete with some 17,000 native plants. (Morse et al. 1995, Morin 1995).
Estimates of how fast and how extensively they are replacing natives vary, but no one who has seen the blooms of garlic mustard in eastern forests, the broad yellow fields of star thistle in the West, the hair-thick stands of melaleuca in the Everglades, or the impenetrable mats of water chestnut on southern lakes and rivers can doubt that change is everywhere.
Often a plant that is a normal part of its native environment, becomes a domineering force in its new home. Australian melaleuca grows much more densely in the Everglades than in its native habitat, and has spread at a rate of 29,700 acres a year (Campbell 1994). It has real costs to both wildlife and to the free flowing water regime that filters and provides much of Florida's water. In Utah's Great Basin, European cheatgrass has accelerated fire frequency from every 60 to 110 years to every 3 to 5 years. This volatile invader has come to dominate some 5 million acres in Idaho and Utah. (Whisenant 1990)
Many environmental groups and journalists have eagerly dramatized the invasives problem, aided by scary names like giant salvinia water fern, skunk vine, fire ant, African killer bee, mile-a-minute vine, fishhook water flea, and sudden oak death.
While the problems are often large and even scary (e.g. West Nile virus), the negatives are not the whole story. A complete balance sheet would also note that many introduced and even invasive species have had economic and social benefits. In fact, many species, like kudzu (used for erosion control in the Southeast), were introduced for their benefits and have provided those benefits even as escapees. In this sense many species are unwelcome only in a superabundance or in the wrong place or because they serve no important economic need or the media ignores their services.
The zebra mussel, notorious for clogging power plant intakes, also provides water filtering and clarifying that benefits some plant and fish populations. Louisiana has been trying to create a market for the large muskrat-like nutria, a good source of meat and fur. Tamarisk or salt cedars, were introduced in the early 1800s for their ability to grow rapidly (up to 12 feet a year), provide dense windbreaks, and colonize heavily saline soils where little else will grow. It turns out salt cedar invasions have been a boon to populations of the endangered Willow Flycatcher bird that prefers salt cedars for nesting (Barranco, 2003). Japanese barberry, besides being an attractive ornamental, provides an abundance of fruits for wildlife.
Judgments about some invasives like salmon in the Great Lakes are a matter of environmental preference, while the European honey bee, a continuing boon to farms and gardens across America, appears to have no organized opposition. As we note in our habitat descriptions for individual plants, a great many colonize abandoned and barren lands and this is often a real service.
Nevertheless, the damages and the costs of controlling unwanted and overabundant invasives exceed the economic threats from terrorism. It is also a lot easier to introduce a devastating invasive species like the Mediterranean fruit fly or zebra mussel than to destroy the World Trade Towers. In fact, the great majority of invasive species introductions to date have been accidental in the sense that no one wanted even a deliberately imported plant or animal to destabilize public or private life. One hesitates to imagine the damages that could be inflicted by biological warfare waged via invasive species.
For environmental pessimists the damage done is one more proof that humankind has ruined nature and should not disturb nature's landscape plan. Some have projected present rates of spread into the future ad infinitum without allowing for saturation, the development of natural controls, or other vectors that might slow or stop an invasive. The invasive species issue also has a convenient link to one of the great bugaboos of social activists of all sorts—globalization.
Increased global trade has indeed accelerated the movement of biological agents between countries and radically accelerated its ancient role in the spread of invasive species. Some environmentalists have already nominated free trade as the primary villain. Forestry activist and respected plant ecologist Dr. Jerry Franklin has declared, “It's time to stop moving green plants and raw wood between continents. ...” (McClure, 2003)
While farmers are well aware of the costs of invasive species, they are also frightened by the potential for eco pessimists to capture the issue. “Unless farmers and ranchers become active in their approach to this issue now, due to heavy environmental influence, federal controls could far surpass the type of abuses of power already experienced with the Endangered Species Act,” says Michele Dias, California Farm Bureau Federation Attorney. He noted that the 108th Congress was considering more than 50 bills addressing invasive species. (Dias, 2003)
To see the invasive species issue as a choice between the native environment and alien species, between preservation and human meddling, obscures the real issue. All “native” dominants from Ponderosa pine to the American bison and Canada goose were once successful invasives. The invasive species issue is real, and environmental pessimists can take a major part of the credit for bringing it onto the public stage. The heart of the matter, however, is not how to restore some “native” ecosystem. To do that would we choose from pre-Columbian, pre-Indian, ice age, or pre-ice age? The choice is arbitrary. We will make intelligent decisions only when the debate shifts from the unsupportable notion that “native” is always better to the all important question of how do we manage change in that dynamic system of tradeoffs that is our natural economy.