[NatureNS]Invasive aliens: was re unauthorized vs. OK plants lists

Date: Mon, 01 Nov 2010 20:18:45 -0300
From: Lois Codling <loiscodling@hfx.eastlink.ca>
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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