Such an interesting read! Conservation is all about contradictions. Like any area of research actually..so that's nothing new. But in conservation, more than others, one needs to pick a side and stick to it..at least for a while.
It is true about the environment being in a deep dynamic balance. But just because we have defined it as a 'dynamic balance' in our books and conversations doesn't mean it isn't a contradiction too. What if biological invasions are just another way of the ecosystem trying to cope with the environmental changes, of taking an evolutionary step. Only this time the changes aren't natural but brought about by our actions. Of course we must all have realized by now that the next evolutionary stage will not be as biologically diverse as the one before because we have ensured it won't be. So maybe the answer to managing ecosystems now is to allow these changes and carry out re-introductions in new, suitable habitats rather than historical ones. Maybe we can aid in the evolutionary process by letting go of old ecosystem boundaries and animal ranges. On the other hand, one might argue that if we were to all take this view there'll be nothing left but invasives and deserts and mines. But even that we aren't sure of are we? So who is to say what is the right approach. Just because something was a certain way, doesn't make it right does it! Well, even I don't have a stand on this as yet and I'm trying to find it. This is my biggest concern really..what side will I pick. I would like to believe that maybe we will need to allow ecosystems to achieve a new balance but then..I don't know. Cheers, Payal. On 7 July 2011 06:10, Geoffrey Patton <[email protected]> wrote: > My wife and I were discussing this topic the other day while hiking through > a Maryland park infested with Chinese garlic mustard and Japanese stilt > grass (among other invasives). We'd biked past slopes of kudzu and came from > Florida's expanses of Brazilian peppers and punk trees. Certainly, we > appreciate that Science will note positive aspects in selected situations > where there are temporally-beneficial effects. However, the mantra that > remains to be overturned is that "Any change from the natural evolution of > an ecosystem is, by definition, adverse". Ecosystems took millions of years > of experimentation to achieve a deep dynamic balance. Upset by > out-of-control human intervention can tilt against a healthy balance and > remains counter to maintenance of diversity. > > Cordially yours, > Geoff Patton, Ph.D. 2208 Parker Ave., Wheaton, MD 20902 301.221.9536 > > --- On Wed, 7/6/11, Christopher M Moore <[email protected]> wrote: > > From: Christopher M Moore <[email protected]> > Subject: Re: [ECOLOG-L] Responses to Davis_etal..Nature article on invasive > species > To: [email protected] > Date: Wednesday, July 6, 2011, 6:30 PM > > Thanks for the post David. > > As a newcomer to science (working on my Ph.D.), there were some lingering > questions I had while reading Davis et al. and the responses: Is this how we > want to move forward as a science? What does it mean when we resort to > gathering signatures? Is this how our science should work? What does it > contribute? How should we deal with issues that are debated in a more > productive and less polarizing manner? Personally, I don't think that > petitioning changes ecology nor any other natural phenomena. > > I would like to add Peter Kareiva's blog on the matter to be added to this > discussion: > http://blog.nature.org/2011/06/invasive-species-fight-mark-davis-peter-kareiva/ > > Opening of the piece: "A famous person once observed that the signature of > a civilized mind is the ability to hold two seemingly contradictory ideas in > one’s head at the same time. This is exactly what conservation must learn to > do when it comes to introduced (or what we often call “non-native” or > “invasive”) species." > > Cheers, > > Chris > > On Jul 6, 2011, at 2:18 PM, David Duffy wrote: > > >> Date: Wed, 06 Jul 2011 19:52:27 +0000 > > > > > > > >> Forwarded from rom: Shyama Pagad > >> <[email protected]> on Aliens-L list server > >> > >> Correspondence Nature Vol 475 July 7 2011 > >> > >> ---------- > >> Non-natives: 141 scientists object > >> > >> We the undersigned feel that in advocating a > >> change in the environmental management of > >> introduced species (Nature 474, 153–154; 2011), > >> Mark Davis and colleagues assail two straw men. > >> First, most conservation biologists and > >> ecologists do not oppose non-native species per > >> se — only those targeted by the Convention on > >> Biological Diversity as threatening “ecosystems, > >> habitats or species”. There is no campaign > >> against all introductions: scarcity of resources > >> forces managers to prioritize according to the > >> impact of troublesome species, as in the Australian Weed Risk > Assessment. > >> > >> Second, invasion biologists and managers do not > >> ignore the benefits of introduced species. They > >> recognize that many non-native species curtail > >> erosion and provide food, timber and other > >> services. Nobody tries to eradicate wheat, for > >> instance. Useful non-native species may > >> sometimes still need to be managed because they > >> have a negative impact, such as tree invasions > >> that cause water loss in the South African fynbos. > >> > >> Davis and colleagues downplay the severe impact > >> of non-native species that may not manifest for > >> decades after their introduction — as occurred > >> with the Brazilian pepper shrub (Schinus > >> terebinthifolius) in Florida (J. J. Ewel in > >> Ecology of Biological Invasions of North America > >> and Hawaii (eds H. A. Mooney and J. A. Drake) > >> 214–230; Springer, 1986). Also, some species may > >> have only a subtle immediate impact but affect > >> entire ecosystems, for example through their effect on soils. > >> > >> Pronouncing a newly introduced species as > >> harmless can lead to bad decisions about its > >> management. A species added to a plant community > >> that has no evolutionary experience of that > >> organism should be carefully watched. > >> > >> For some introductions, eradication is possible. > >> For example, 27 invasive species have been > >> eradicated from the Galapagos Islands, > >> mitigating severe adverse effects on endemic > >> species. Harmful invasive species have been > >> successfully kept in check by biological, chemical and mechanical means. > >> > >> The public must be vigilant of introductions and > >> continue to support the many successful management efforts. > >> > >> Daniel Simberloff* University of Tennessee, Tennessee, USA. > >> [email protected] > >> > >> *On behalf of 141 signatories > >> [<http://www.nature.com/nature/journal/v475/n7354/extref/475036a-s1.pdf > >http://www.nature.com/nature/journal/v475/n7354/extref/475036a-s1.pdf] > >> (see go.nature.com/f1eqjn). > >> > >> ---------- > >> Non-natives: put biodiversity at risk > >> > >> Bias against non-native species is not > >> xenophobic (Nature 474, 153–154; 2011) — it has > >> a sound scientific foundation. The non-native > >> status of a species is highly relevant to > >> assessing its potential environmental and > >> economic impact. Unrestrained growth and > >> environmental damage follow when there are no > >> natural enemies in newly colonized areas. This > >> is not necessarily a sign of an invader’s > >> superior evolutionary fitness: it may lead to a > >> population collapse due to overexploitation of resources. > >> > >> Non-native species can increase the variety of > >> species in a community, but it is an > >> oversimplification to equate this with increased > >> biodiversity, of which species richness is only > >> one component. Surviving populations of native > >> species may shrink or become restricted to > >> poor-quality marginal habitats. Such unevenness > >> hardly contributes to a more diverse community. > >> > >> The genetic diversity of invaded communities may > >> decrease because of bottlenecks: native > >> genotypes disappear as populations fall, whereas > >> the invaders originate from very few initial colonizers. > >> Establishment of non-native species inevitably > >> decreases global diversity. Australia, for > >> example, was unique in having no placental > >> mammals; their introduction by humans made the > >> continent ecologically more similar to the rest of the world. > >> > >> Andrei Alyokhin University of Maine, Maine, USA. > >> [email protected] > >> > >> ---------- > >> Non-natives: plusses of invasion ecology > >> > >> Contrary to the implications of Mark Davis and > >> colleagues (Nature 474, 153–154; 2011), invasion > >> ecology has given us valuable insight into the > >> effects of new species on ecological function > >> and into some of the precipitous changes we may face in the coming > decades. > >> > >> Invasion ecologists generally assert that only a > >> very small fraction of non-native species harm > >> their new ecosystems. This position emerged as > >> early as 1986 and was mainstream in the era that > >> Davis and colleagues claim as the nadir of ecological nativism. > >> > >> It is unfair to characterize any scientific > >> discipline solely by past failures and to ignore > >> its successes. Invasion ecology is making real > >> progress with defining impact and characterizing > >> risk. Let’s not throw up our hands in despair just yet. > >> > >> Julie L. Lockwood Rutgers, > >> The State University of New Jersey, USA. > >> [email protected] > >> Martha F. Hoopes Mount Holyoke College, Massachusetts, USA. > >> Michael P. Marchetti California State University, California, USA. > >> > >> ---------- > >> Non-natives: four risk factors > >> > >> Mark Davis et al. set an unrealistically high > >> bar for those making management decisions about > >> exotic species (Nature 474, 153–154; 2011). > >> Control is often easier, cheaper and more > >> effective soon after detection (R. A. Haack et > >> al. Annu. Rev. Entomol. 55, 521–546; 2010). We > >> agree that research on ecosystem impact is > >> necessary, but such studies can take years. > >> Meanwhile, we suggest that control priorities > >> for potential invasive species could be based on > >> easily available data about natural history and > >> evolutionary ecology. We propose four guidelines > >> for identifying such invasives. > >> > >> An exotic organism may be more likely to invade > >> and cause disruption the greater its rate of > >> reproduction; the greater its dispersal ability; > >> the closer (phylogenetically) its preferred food > >> in its native range is to an abundant taxon in > >> the new range; and the farther away > >> (phylogenetically) its predators and pathogens > >> are in its native range from those in its new range. > >> > >> For example, the red turpentine beetle > >> (Dendroctonus valens) is not particularly > >> disruptive in its native range in North America > >> because it attacks only trees that are already > >> weakened. In China it attacks and kills healthy > >> trees (Z. Yan et al. Biodivers. Conserv. 14, > >> 1735–1760; 2005). The reasons for this beetle’s > >> success as an invasive include its high > >> dispersal and reproductive rates, its affinity > >> for Chinese pines closely related to those it > >> feeds on ‘at home’, and the lack of predators or > >> pathogens phylogenetically similar to ones found in North America. > >> > >> Manuel Lerdau Xishuangbanna Tropical Botanical > >> Garden, Chinese Academy of Sciences, Menglun, > >> Yunnan, China; and University of Virginia, Virginia, USA. > >> [email protected] > >> Jacob D. Wickham Institute of Chemistry, Chinese > >> Academy of Sciences, Beijing, China. > > > > > > David Cameron Duffy > > Professor of Botany and Unit Leader > > Pacific Cooperative Studies Unit (PCSU) > > University of Hawai`i > > Christopher Moore, Ph.D. student > Program in Ecology, Evolution, and Conservation Biology > Department of Biology > University of Nevada, Reno > > Office: Fleishman Agriculture Building 140 > Webpage: http://www.unr.edu/~cmmoore > Email: [email protected] >
