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Hi Again, Nov 26-29, 2010
Further to my e-mail of Nov 17 [below], and I don't want to beat a dead
horse, but in addition to matters that I left for later I notice that I
neglected to comment about Buckthorn beyond observing that it now is
spreading rapidly here.
It sometimes forms dense stands (~40 stems/m^2) in glades created by
windfall or selective cutting, within several years of this canopy
disturbance, and grows rapidly (in 3 years it likely captures as much carbon
as Ash or Maple seedlings would in 30) so I suspect it does a good job of
capturing nutrients that are released by dead roots, litter etc. and in
addition likely increases soil porosity.
By preventing native trees from becoming overstocked it may act as a
good nurse crop (speculation at this point). But nurse crop or not, it does
a good job of feeding some birds.
-----------
Going on to other aspects and considering first "the direct squeezing
out of native species of plants by competition"--- This no doubt happens but
I wonder whether the squeezing out is permanent or whether it is just
another step in the circular cycle of change.
Sometimes these 'invasive' plants seem to hit a barrier. I don't know
what is happening province-wide, but Epipactis helleborine spread rapidly in
my North Alton woodlot and into the Kentville garden some years ago but now
seems to be much less common.
-----
Moving on to "...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.",
this problem seems to be somewhat artificial.
A good many native plants strive mightily to avoid feeding insect
herbivores but, even when they manage to do so, their fixed carbon
eventually manages to feed something; directly or indirectly. The same
applies to alien plants. The tops ( including leaves, fruit & seeds) and
roots of alien plants don't just keep accumulating. Therefore they must
participate in energy flow and sustain at least some other chains of
organisms.
Some canny rodents make tidy nest linings from the inner bark of dead
Poplar but I have watched a Red Squirrel vigorously stripping inner bark
from dead Liliac and trying to yank yarn from indoor-outdoor carpet;
presumably for nest linings.
-----------
And finally, moving on to the third "the dilution of the biogeographic
integrity of the biota": it seems to me that fussing about said dilution
reflects an amazing detachment from reality. Surely, to take just one
example, the massive fragmentation of landscape integrity, due to highway
construction, is orders of magnitude more important: especially if you are
some amphibian or reptile who feels compelled to travel to some ancestral
pond or sandy slope.
The one element of biogeographic integrity that is a bit disturbing (to
me) is the almost certain distortion or contamination of genuine natural
ranges at relatively small scale (e.g. within Eastern North America, within
NS or within Counties) by the accidental or intentional transport of plants
and animals.
Because human activity can bring e.g. European organisms to the East
Coast then it seems almost certain that transport activity within a
continent, country or local jurisdiction will move some 'native' organisms
to locations where they would otherwise have been absent.
Combine this potential with the relatively primitive state of biological
inventory of e.g. insects and you have a compelling reason to get on with
the job of biological inventory.
Yt, Dave Webster, Kentville
.
----- Original Message -----
From: "David & Alison Webster" <dwebster@glinx.com>
To: <naturens@chebucto.ns.ca>
Sent: Wednesday, November 17, 2010 9:28 PM
Subject: Re: [NatureNS]Invasive aliens: was re unauthorized vs. OK plants
lists
> Hi Fred & All, Nov 17, 2010
> Thanks for your comments. It has taken a while, but at last I have set
> aside a few minutes to reply in part.
>
> I had not intended to include Quebec or Ontario in 'Eastern Canada'
> because, in this subject matter, I believe only what I have been able to
> observe directly and my time has been spent mostly in NS.
>
> "Wild spaces" in cities, often little more than unofficial garbage
> disposal sites, are no doubt frequently vulnerable to being taken over by
> unusually tough plants and this will usually mean non-native plants. Human
> settlement tends to de-water landscapes and this effect reaches a maximum
> in
> many cities. Former relatively stable stream flows, and relatively stable
> soil moisture regimes on ravine sides and flood plains, are replaced by a
> feast or famine water regime; flash flood or sopping wet during rain
> events
> and parched a few days later. The soil on ravine sides is often a mixture
> of
> construction waste, appliances, surplus fill, plastic sheeting, etc.; a
> challenge for even tough plants. So when "wild spaces" in cities are
> invaded
> by aliens it may be germane to consider why this happens.
>
> Buckthorn (Rhamnus frangula) has begun in recent decades to spread
> rapidly here, after spending about 250 years doing nothing and this
> touches
> on the question of why plants "become invasive". In this case, it may be
> related to changes in land use.
>
> Until about 1960 it was common practice here to pasture cattle in
> woodland, especially cut areas, near rural settlements until the hay of
> meadows had been cut. As agriculture shifted from most farmers having a
> few
> cattle to few farmers having many cattle, that practice was abandoned and
> Buckthorn was protected from the lethal effects of grazing.
>
> In 2006 I checked a nearby site for possible control of Buckthorn aby
> cattle as described in the following paste.
>
> START OF PASTE
> Dear All, Sept 24, 2006
> Further to my comments of Sept 21 (below) I visited this stand today [by
> walking East of Kentville, to examine the bushes near the fence that is
> just north of the rail trail]. Cattle have been pastured on the north
> side of this fence since at least 1960 but I don't recall ever having
> seen horses in this pasture.
>
> Briefly, Hawthorn (_Crataegus_)and Common Buckthorn (_Rhamnus
> cathartica_) were browsed about equally, just back to the wire or a
> tongue length beyond, and these shrubs were relatively common near the
> fence, as compared to abundance at distance from the fence.
>
> In contrast, Alder-leaved Buckthorn (_Rhamnus frangula_) was browsed well
> back from the fence, if anything more than Chokecherry (_Prunus
> virginiana_) and was relatively infrequent near the fence.
>
> It would appear, unless horses have been pastured here in recent years,
> that Alder-leaved Buckthorn is a favourite treat of cattle and therefore
> easily kept in check by cattle.
>
> Yours truly, Dave Webster, Kentville
>
>
>
> EXCERPT FROM SEPT 21 POST\\\\\\\\\\\\
> If it did come to NS with the Acadians then some factor must have
> held it in check until recently, and livestock teeth, the bane of young
> woody plants is the obvious suspect. [I just remembered a stand of
> Buckthorn that probably extends to a pasture fence. Will check it one of
> these days for a possible browse line.]
> END OF EXCERPT\\\\\\\\\\\\\
> END OF PASTE
>
> Norway Maple is a common ornamental here and spreads readily in town
> provided it is not mowed. I have never seen it in woodland and doubt that
> it
> would persist in a closed canopy here past 50 years or so of age because,
> even in a narrow hedge, it seems to become long and lanky in search of
> light. I would be interested to hear how it behaves elsewhere.
>
> My subliminal impression of alien herbaceous plants is that they
> support
> a wealth of insect life and insect life supports other life forms---
>
> One example that found me by accident is Mustard White, a putatively
> uncommon beast that would likely have become very rare if it had been
> denied
> the opportunity to exploit a non-native crucifer; Cardamine pratensis.
> Where
> C. pratensis is present in eastern Kings Co., Mustard White is frequently
> abundant. A cut and paste from a 2004 e-mail (also partly a cut & paste)
> will avoid repetition: at least at the typing end.
>
> After having seen this unknown white butterfly many times near the
> entrance to my woodlot over several years, curiosity took over and I
> rigged
> up an insect net from muslin and a kitchen strainer hoop: son-of-a-gun;
> Mustard White.
>
> START OF PASTE
> Hi Randy & All, Oct 28, 2004
>
>
>
> The effects of adding many weedy species of herbaceous plants, for
> example, might, if considered objectively, be found on balance to be
> positive.
>
>
>
> I'd love to read an example of this. And by "positive", do you mean,
> "positive to people"?
>
>
>
> Hi Randy & All, Nov 1, 2004
>
> As explained in my e-mail of May 16, 2004 (excerpt pasted below), I
> think Mustard White (Pieris napi) would now be less common in NS if it had
> failed to adapt to introduced plants. So these introduced plants have
> probably had positive effects from the standpoint of insect diversity and
> for the welfare of the species in question.
>
> START OF PASTE
> Of the various known food plants listed in Opler & Malikul (1992;
> Peterson Eastern Butterflies), Morris (1980; Butterflies and moths of
> Newfoundland and Labrador), Ferguson (1954) and Scott (1986; as listed
> by C. Majka e-mail of 18-May-2003) all are either cultivated,
> introduced, adventive, rare or with a restricted distribution.
>
> For example--
> 1) Toothwort (Cardamine <--Dentaria diphylla); Never found south of
> Digby/Canso line, with a restricted habitat (rich moist soil) and now
> probably less common due to grazing and tillage.
>
> 2) Watercress (Rorippa nasturtium-aquaticum)<--(Nasturtium officinale);
> Escape from cultivation. Probably the food plant for the ca. 1864
> Halifax area population. Also, in 1864, lepidopterists were likely more
> abundant in the Halifax area than elsewhere. And those cold water
> runnels of the Halifax area with watercress have long since been
> converted to sewer routes.
>
> 3) Rock Cress (Arabis spp.); Rare and north of the Digby/Canso line.
>
> 4) Cardamine pratensis var. palustris; Scattered in central Cape Breton.
>
> 4a) Cardamine pratensis; Introduced. Not reported as a food plant but,
> based on the var. palustris being used, expected and the North Alton
> colony confirms this.
>
> 5) Rorippa palustris <-- islandica; Partly adventive and not commonly
> encountered.
>
> 6) Hedge-mustard (Sisymbrium spp.); Two introduced species.
> END OF PASTE
> END OF PASTE
>
> Yt, Dave Webster, Kentville
> ----- Original Message -----
> From: "Frederick W. Schueler" <bckcdb@istar.ca>
> To: <naturens@chebucto.ns.ca>
> Sent: Sunday, October 31, 2010 10:49 PM
> Subject: Re: [NatureNS]Invasive aliens: was re unauthorized vs. OK plants
> lists
>
>
>> 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 adopt the trappings that facilitate
>>> survival.]
>>>
>>> Or was it to solicit contributions to save... whatever fits...; our
>>> native pristine wetlands...the Acadian Forest... or at least cover the
>>> cost of collecting the contributions ?
>>>
>>> Proceeding now from the general to the particular, if we are to
>>> " ordinarily rule against importation of any non-native species. " I
>>> guess this means we should, while there is still time before these
>>> non-native species become vicious, wipe out the Sable Island Ponies and
>>> of course outlaw most agricultural crops and livestock ( e.g. horses,
>>> cattle, sheep, goats, asparagus, potatoes, oats, barley , wheat, beets,
>>> carrots, tomatoes, apple, pear, ....and rabbits; especially rabbits)
>>> and, to be on the safe side, we should bring back non-selective
>>> herbicides and wipe out the mostly non-native vegetation of lawns,
>>> ornamental shrubs and flower gardens.
>>>
>>> And if we are going to "ordinarily rule against importation of any
>>> non-native species", and bearing in mind that native species are already
>>> here and thus do not need to be imported, I guess this means that we
>>> should close the border to all trade involving plants (or animals by
>>> extension).
>>>
>>> Hopefully those non-native plants that travel by wind, water, flesh
>>> or fowl will do the right thing and bail out before they cross the
>>> border.
>>>
>>> But on the other hand, perhaps those very aggressive invasive
>>> species will be inconsiderate enough to cross the border anyway. In fact
>>> that might be a practical working definition of this class. Therefore,
>>> on this basis, all plants should be on the white list.
>>>
>>> Yt, Dave Webster, Kentville
>>>
>>
>>
>> --
>> ------------------------------------------------------------
>> Frederick W. Schueler & Aleta Karstad
>> Bishops Mills Natural History Centre - http://pinicola.ca/bmnhc.htm
>> Thirty Years Later Expedition -
>> http://fragileinheritance.org/projects/thirty/thirtyintro.htm
>> Longterm ecological monitoring - http://fragileinheritance.org/
>> Daily Paintings - http://karstaddailypaintings.blogspot.com/
>> http://www.doingnaturalhistory.com/
>> http://quietcuratorialtime.blogspot.com/
>> RR#2 Bishops Mills, Ontario, Canada K0G 1T0
>> on the Smiths Falls Limestone Plain 44* 52'N 75* 42'W
>> (613)258-3107 <bckcdb at istar.ca> http://pinicola.ca/
>> ------------------------------------------------------------
>> ------------------------------------------------------------
>
>
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