Jim, I must in turn respectfully disagree that "introduced species are bad, no ifs, ands or buts." Here in Vermont, our lilacs and our red clover are both non-native (if you want to look at 1492 as the 'cut-off' for determining "native-ness"). The red clover is our state flower, and the lilac is a perennial favorite. They became naturalized...red clover is a preferred food for deer in our area. I think "bad" is a value-laden term, and a very relative one at that. If an exotic is negatively impacting something we value, then the creature or plant or algae is "bad, no ifs, ands or buts." If it naturalizes or something eats it or it has an obvious ecological benefit, then it is viewed with neutrality tempered with skepticism. Too many ecological terms are become over-used and hence meaningless, or at least vague. "Invasive" should pertain to a particular species' behavior, not neccessarily its origins. After all, how far back does one go to determine place of origin? If you go back far enough, humans aren't even indigenous to North America; "we" came over across the Bering Strait, if you go by the fossil record. Since so many creatures are classified based on behavior, "invasive" should indicate a set of behaviors that are exhibited by a species -- and it usually does. Yet this also begs some questions: to some extent, every plant exudes allelopathic compounds into the surrounding soil to protect itself from pathogens and from encroaching neighbors. So how much "invasive" behavior is simply good strategic defense or adaptive behavior? How about poison ivy? Some states list it on their lists of invasive plants, yet it is considered "native" to North America. There is a species of Daphnia in Lake Constance (between Germany and Switzerland) that has adapted over the past thirty years or so to actually eat toxic cyanobacteria. (http://www.cnn.com/NATURE/9910/01/pollution.eaters.enn/index.html) Who is to say that ecosystems can't adapt to a noxious invader or that all non-natives must be eradiacted in order for an ecosystem to be "healthy"? In addition (and in closing, so as not to bore everyone to tears!), why are "invasions" seen as bad and never as part of the evolutionary process? Rather than make the plant or animal the "bad guy", why not recognize that species hitch-hike-- it is what they do, it is how they travel, and it is how the planet has operated for millenia. When land bridges arose, animals and plants moved in vast quantities and at great speed. Landscapes changed forever. The fossil pollen record proves that. I realize that human activity is responsible for lots of introductions, but they don't all end in disaster. First, there is the Rule of Tens: 10% of introduced species can survive in their new habitat; 10% percent OF THOSE actually escape and survive outside of cultivation; 10% OF THOSE become "invasive." Second, the Panama Canal was one example of a sudden, major introduction of two riverine habitats -- "all of the original species found in each stream in a 1916 survey are still there." (http://usinfo.state.gov/gi/Archive/2004/Aug/23-973558.html) Anyway, it's some food for thought. To paraphrase Willy Wonka, a little paradigm shift now and then is treasured by the wisest men. Cheers, Kelly Stettner Date: Tue, 20 Nov 2007 10:32:12 -0200 From: "James J. Roper" <[EMAIL PROTECTED]> Subject: Re: ECOLOG-L Digest - 15 Nov 2007 to 16 Nov 2007 (#2007-310)
Kelly, I respectively disagree. Introduced species are bad, no ifs ands or buts.... Some of them are naturalized and so there is probably absolutely nothing we can do about them. The others often have potential for causing catastrophe, and it is hubris to think that we can just USE them to suit OU= R purposes (of what, fixing something that we already messed up?) with no repercussions. Also, your argument below is circular. An ecosystem that is very diverse has the exotics as part of the calculation of diversity, so less diverse will have fewer species overall. Also, healthy does not equal diverse - else deserts and alpine systems are all unhealthy. If you say that within any biome, the most healthy are the most diverse, I bet you do not have the data to support that stand. Is leaching copper good? What does "filter" toxics mean? The take toxins from the soil and do what with them? And, what do they do in areas that have no toxins when they escape cultivation? Complicated issues, and I think the best answer is never introduce, plant natives, eliminate exotics. Cheers, Jim Black River Action Team (BRAT) 45 Coolidge Road Springfield, VT 05156 [EMAIL PROTECTED] http://www.blackriveractionteam.org ~Making ripples on the Black River since 2000! ~ --------------------------------- Be a better sports nut! Let your teams follow you with Yahoo Mobile. Try it now.
