GENERAL LINKS:
Invasive Exotics: Why Should We Remove Them? One man's argument. And The EPA's point of view, entitled "Landscaping with native plants", including discussion of why non-native species and conventional lawns are bad ideas for your landscaping needs. The US National Arboretum also has a page on the subject. USA Today discussed why lawns in particular are bad things. The threat to the National Wildlife Refuge system is so serious that even traditionally anti-environmental Republican US senator Larry Craig has supported taking action. And no discussion on this topic could be complete without a few words from Dan Simberloff, probably the US' reigning expert.
And what should you do after removing exotic species?
Replace them
with native species, of course!
Have exotic plants in your yard gotten so out of control
that you can't possibly remove them all? It's Captain Good Plant to the
rescue!
The U.S. federal Invasive Species Information System. The Feds have also published a fact book on the issue, Invasive Plants: Changing the Landscape of America.
A few professors at the University of Georgia have set up a huge archive of images of exotic species.
The international Invasive Species Specialist Group.
Weeds Gone Wild is devoted specifically to attempting to protect natural areas from exotic plant species.
The Nature Conservancy's Wildland Invasive Species Team.
The University of Tennessee's Institute for Biological Invasions has an even bigger and more comprehensive links section than I do, as well as images of the covers of an amazing array of books on the topic.
The Introduced Species Summary Project is affiliated with a Columbia University course in Invasion Biology. There's also an entire scientific journal devoted to the study of Biological Invasions.
LINKS FOR PARTICULAR ORGANISMS:
For a less scientific, more artistic angle on the
issue, read Wisteria
Blue, a brilliant poem by Joe Clark.
The No Ivy League targets one particular ecological menace: English Ivy, Hedera helix.
Nonindigenous Fish Distribution Information from the USGS Florida Caribbean Science Center.
Non-native Reptiles and Amphibians of the United States, courtesty of the Kleberg Wildlife Research Institute.
An article on exotic insect pest defenses from the Christian Science Monitor.
While European Starlings and House Sparrows get a lot of attention in the US, the worst invading bird species is the Mute Swan. It has been studied the most in the Chesapeake Bay region, but is also a problem in many other areas, including Pennsylvania, Wisconsin, and even Canada.
One of the most complex plant invasion issues is the Common Reed, Phragmites australis. Once thought to be completely foreign to North America, fossil evidence (ground sloth dung) indicates that there are native American populations. We now know that there are both native and non-native Phragmites in the US. It is difficult but not impossible to tell the two apart. One company even offers genetic testing to differentiate native from exotic Phragmites. They definitely have different impacts on native ecosystems, as native Phragmites harbors many bird species, while the exotic version hosts very little animal or other plant life because it decomposes much more slowly than the native does.
STATE AND REGIONAL LINKS:
Hawai'i's ecosystems are among the world's most degraded, thanks mostly to the flood of exotic species that have become established there with the help - either intentional or accidental - of humans. The Bishop Museum has issued trading cards of Good Guys and Bad Guys to help everyone tell the exotics from the natives (I'd LOVE to have a set, if anyone out there can get me one!). See also Hawaiian Ecosystems At Risk.
For this part of the US we have the Southeast Exotic Pest Plant Council. For those a bit further north, there's Control of Invasive Non-native Plants, a guide for the Mid-Atlantic states.
Florida is another hotbed of exotic species problems. For a historical perspective, see the timeline from the state Aquatic Plant Control Program. Nonindigenous Freshwater Species of Florida is actually a book by James McCann, Lori Arkin, and James Williams; made available on-line by the University of Florida's Center for Aquatic and Invasive Plants.
Invasive Alien Plant Species of Virginia.
Alien Ocean focuses on the exotic species that threaten the ecology of Chesapeake Bay, including Mute Swans, Nutria, Zebra Mussels, Purple Loosestrife, Water Chestnut, and Phragmites.
Non-native Plants of Delaware.
New York's Least Wanted List of exotic plants; not to be confused with the "Top 20" invasive plants list of the Invasive Plant Council of New York State. Plus, a recent article on exotics in NY-based Clearwaters magazine, a publication devoted to water quality issues.
Information on selected invasive species of the northeastern US. Informative and extensive, but kinda hard to read. The Invasive Plant Atlas of New England is much easier.
Alien invasions of Massachusetts Woodlots and what to do about them; and a more general page on Invasive Plant Species of Massachusetts.
Connecticut has lots of information on invasive exotic plants. See Invasive Exotic Plants from the Connecticut College Arboretum; Invasive Non-native Plant Species from the Torrey Herbarium; and the Connecticut Invasive Plant Working Group homepage.
Non-native Invasive Plants of New Hampshire.
Invasive Species of Wisconsin.
The National Audubon Society recently published a great article, "America's Largest Weed" in Audubon magazine about one particularly bad - and yet dangerously popular - type of invasive species, Eucalyptus trees.
The Biological Invasions Program of the San Francisco Estuary Institute.
The Washington State Noxious Weed Control Board.
And for a perspective from outside North America, the Regional Biological Invasions Center in St. Petersburg, Russia.
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PHOTOS:
The Japanese Beetle is a well-known garden pest in the U.S.
My Ph.D. research at Duke involves studying the ecology of nonnative dragonflies like the Scarlet Skimmer, which has been accidentally introduced from tropical Asia to Florida and Hawai'i, probably through larvae hiding in shipments of tropical fish or aquatic plants.
Exotic species are nothing to laugh about, but there's a movie about Cane Toads (also known as Marine or Giant Toads) which even cracks me up. They've been spread from Latin America to Florida, Texas, Hawai'i, and Puerto Rico, mostly thanks to the sugar industry. We can also thank sugar barons for stupidly introducing the Indian Mongoose to Hawai'i and the Caribbean, causing the extinction and endangerement of many bird and reptile species.
Hunters and fishermen are also prone to ignorantly release targets for themselves in ecosystems where they don't belong. That's why you can now find abundant East African Oryx in New Mexico, causing traffic hazards and destroying desert habitats, reproducing far faster than the hunters are shooting them. Hunters also have introduced exotic plants like the Japanese Clover by planting them for game forage, even though most birds and mammals prefer to eat native species.
Florida has only one native species of Anole, but several others have escaped there. The Brown Anole is by far the most common, now outnumbering even the indigenous Green. Bark and Knight Anoles are more localized, so far. Other exotic lizards now established in Florida, mostly thanks to the pet trade, include the Common Green Iguana and the Brown Basilisk as well as several species of gecko.
Probably the predominant source of exotic plants is the horticulture and landscaping industry. They brought us Water Hyacinth, which now costs the US government over 1 million dollars per year to control while also blocking boating routes and threatening ecosystems.
Another troublesome plant is Spotted Knapweed, which threatens native plants and the butterflies that rely upon them for food; it also makes farmland and grazing land less productive, costing those industries lots of money.
Not all exotic species cause problems: the European herb Heal-All grows mainly in disturbed habitats like roadsides, and so far has shown no direct impacts on native species. But other species have seemed harmless for years, then suddenly become troublesome, and so all non-native species need to be watched...
My page of Hawai'i photos includes dozens more of exotic species, which outnumber natives in that island archipelago now; some biologists there say that it is now nearly impossible to find a native species of terrestrial plant or animal near sea level.
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