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Breton.&nbsp;</div><div><br></div><div>Roland (revi This is a multi-part message in MIME format. --Boundary_(ID_WC11dR/zm3tj9tAKsbmM1g) Content-type: text/plain; CHARSET=US-ASCII; format=flowed Content-transfer-encoding: 7BIT Hey all you evolutionists out there, why are you trying to prevent 'natural selection' and 'survival of the fittest'? Lois & Don Codling On 31/10/2010 11:49 PM, Frederick W. Schueler wrote: > David & Alison Webster wrote: > >> Executive summary: >> I can not think of one non-native plant that has caused a serious >> problem in Eastern Canada. Some, for a few years, may locally >> overwhelm native plants. But sometimes native plants overwhelm other >> native plants. > > * there's a lot of good points here, but I think the questions > relevant to the executive summary are "how far west does eastern > Canada extend," and "what constitutes a problem." > > If Toronto is allowed to be part of "eastern Canada," then between > European Phragmites, Norway Maple, Goutweed, Dog-strangling vine, > Flowering Rush, Pink Jewelweed, Buckthorns, Narrowleaf Cattail, Garlic > Mustard, and a host of other alien plants, there's not much doubt that > even forests and other "natural" habitats have had their native > species considerably diluted, and one can't say how much truer this > would be if Purple Loosestrife and Saint Johnswort hadn't been knocked > out by biological controls. I described the alienness of the Toronto > area in > http://groups.google.com/group/naturelist/msg/661b4fcb53862d34?hl=en. > > When I commented to Bev Wigney this summer about the relatively native > vegetation in Nova Scotia, she promptly reminded me of a lot of alien > species that were all over the place, but that weren't on my Ontario > alarm list (her homesite is equally divided among two alien species of > Cherries and Black Locust, with wide patches of Goutweed, Dame's > Rocket in the woods, and Celandine scarce only because she'd been > pulling it all summer) > http://karstaddailypaintings.blogspot.com/2010/09/old-black-locust.html#more > > There's three kinds of problem that alien plants can cause, first is > the direct squeezing out of native species of plants by competition. > The second is the redirection of the photosynthate they produce into > their own growth and away from Insect herbivores, and direct > attributes of the native species that might otherwise feed or benefit > native animals. > > The third is more abstract: the dilution of the biogeographic > integrity of the biota. If one accepts maintaining as much as possible > of the biogeographic differences among places as a proper goal of > People who live on the Earth, then the dilution of native species is > an absolute harm that's done by all alien species, including > ourselves, against which any human action that may introduce new > species must be balanced. But of course biogeographic integrity is not > a widely endorsed as a motivation, and its maintenance is derided as > an overt motivation even by some invasive species biologists. > > The thing about invasive species is that they're such magnificent > Plants that struggling against them in an open-minded way teaches the > clear lesson of the importance of loving your enemies. > > fred schueler. > ============================================================ > >> The longer version: >> Labels tend to cloud rather than clarify matters, as I will >> discuss later. First though one should get the history correct. >> >> Based on Gray' s Manual (7 th ed; 1908), Purple loosestrife (as >> Lythrum salicaria and as L. salicaria var. tomentosum) must have >> landed in North America way before 1900. By the time this 7 th ed. >> was compiled and printed, typical PL was present in N.E., Del. & D.C. >> and var tomentosum was present from e. Que to Vt and in s. Ont. Much >> of these range descriptions were likely based on pre-1900 collections. >> Someone who has access to earlier editions of Gray's manuals >> and/or Harvard/Yale herbaria catalogues will be able to establish a >> more precise date but I would guess well before 1800 and perhaps >> partly or entirely as ornamentals. >> >> The 7th ed. says L. salicaria is 'local'. In the 8th ed. (1950) >> this is expanded to 'locally abundant, often too aggressive in >> choking out native vegetation.' . >> >> LABELS: Labels are fine if in, e.g. ecology, if they are used to >> characterize some set of responses to some defined set of conditions. >> The label "Old Field Spruce" e.g. has been used to refer to the >> forest cover that initially replaces the mostly herbaceous ground >> cover of abandoned farmland; the older trees being predominantly >> Spruce (favoured by exposed mineral soil) and the later arrivals >> being predominantly Fir (favoured by litter). >> >> I suppose from the viewpoint of these displaced shade-intolerant >> herbaceous plants, these Spruce could be considered "Invasive" but >> more objectively they are just players in a process of secondary >> succession. >> >> And secondary succession never sleeps. Shortly after crustose >> lichens establish borders they are swamped by foliose lichens that >> prosper at the edges and decline in the middle. And comparable >> processes of encroachment, prosperity at the fringes with stagnation >> in the interior can be seen in the vegetation of barrens, bogs and >> even in woodland (esp at the level of air photographs). >> But labels, such as "Invasive Alien" that are assigned on the >> basis of prejudice or labels that have emotional overtones can >> obstruct clear thought and consequently belong more in the realms of >> politics or propaganda than in natural history or biology. >> >> In many and perhaps all cases the question is not "Why did this >> plant become invasive ?" but "Why did it become fashionable to call >> this plant invasive ?" Or even "Why did it become fashionable to >> call alien plants that do unusually well here invasive ?" >> >> Was it to drum up support for field research ? [It is >> unfortunately likely true that a research proposal to avert some >> crisis is more likely to be funded than a proposal to just study the >> natural world. If there is no crisis in sight then it will be >> expedient to invent some. Surviving cultures are those that ado