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It does seem that I can't get away with this. I can't get on line long
enough to send an e-mail. DW :>)
Hi Steve & All, Aug 21, 2008
But why should one judge a plant or animal on other than its
behavior & properties (i.e. merits) ? Is it not unreasonable to condemn
something simply because it is alien ?
To refresh your final comment, "Maybe someone else (or you yourself)
can come up with an actual example of your point, where you seem to
claim that
an invading species can come in and wax fruitfully in a new zone without
damaging the ecosystem, merely by utilizing an unused resource?"
For starters one must strike the pejorative labels; invasive, alien,
invading... So the question, 'How can this despicable, no-good, evil,
alien, invasive destroyer of all that is good have positive features ?'
becomes 'How does the organism in question behave under defined,
specific circumstances ?'
Human activity, especially when magnified by ox power, horse power,
teeth of domesticated grazers, tillage... generates bare earth or areas
of sparse vegetation that is readily "invaded" by weedy shade-intolerant
alien species and in the absence of such "invaders" unprotected soil is
readily washed into waterways and lost. Just for soil conservation
alone, these weedy species have been of great value and it goes on and
on. Where fingers of disturbed soil reach into woodland (e.g. along
trails/sparsely vegetated roadways) the plants may follow but I can
think of no shade-tolerant woodland species that have been displaced in
healthy undisturbed woodland.
[ I am no fan of Epipactis, and pull it out when I notice it, but it
grows mostly in unoccupied soil. Buckthorn is locally invasive in opened
woodland (I have cut a lot of that just to weaken it but it is tougher
than Speckled Alder) and probably can persist for >30 years even in a
closed canopy by growing up.]
When trees fail, due to air pollution, and the canopy opens
sufficiently to support shade-intolerant species then one may expect
some weedy alien (of the anthropogenic steppe) to make use of this but
the fault lies not with the 'invasive alien' but with the disruptive
effects of air pollution and with human activities that generate it.
Returning briefly to Japanese Knotweed there may be situations
somewhere where the label invasive is warranted. From anything I have
seen in NS it is simply incorrect here. On the subject of plant behavior
there is no substitute for ground truth.
To quote Roland and Smith "Roadsides and waste ground around
towns...and occasionally found about older houses and along fences." It
has been in Eastern North America for over 100 years but it is still
restricted to small patches, most of which I suspect were planted by
accident when fill that contained rhizomes was hauled to the roadside or
building lot. That description from Roland & Smith does not sound like
something that is able to displace native plants in pristine wilderness.
Many of our rare plants are Arctic Alpine; plants of cliff ledges,
bluff tops, scree and other relatively inaccessible places. They may be
locally abundant but some are sparse. I don't recall details now but,
several years ago, rock climbing was being promoted to increase park
usage (in the Highlands park as I recall). Now that is invasive.
Yours truly, Dave Webster, Kentville
Stephen Shaw wrote:
> Quoting David & Alison Webster <dwebster@glinx.com>:
>
>> Randy Lauff wrote:
>>
>>> 2008/8/9 David & Alison Webster dwebster@glinx.com
>>> <mailto:dwebster@glinx.com>
>>
>>
>>> Now herbicide is being used in the highlands park (injecting each
>>> stem)... but mowing, whenever the shoots reach about 3 dm, would
>>> be more efficient and effective.
>>>
>>> I fail to see how mowing could be either more efficient or
>>> effective. Mowing has to be done several to many times a year (every
>>> year!) due to the vigorous growth. A minimum effective dose of
>>> herbicide would solve the problem in one bout.
>>>
>>> David Webster continues to be carefree about introduced species,
>>> including invasive ones. And now he's against the National Park
>>> trying to maintain natural biodiversity?
>>>
>> Hi Randy & All, Aug 15, 2008
>> If you read my original post you find no indication that I am
>> against control of this plant in the National Park.
>
> [section cut out]...
>
>> I think we should judge plants and animals by behavior and
>> properties not by point of origin. In general, when a plant is
>> invasive it is because there is some underutilized resource that
>> happens to meet their (its) requirements.
>> Yt, DW
>
>
> Hi Dave:
> Irrespective of the merits/demerits of Japanese Knotweed, but
> regarding your
> last paragraph reproduced immediately above: I think this idea should
> be a
> hard sell and doubt you can get away with making it. Invasive species
> usually
> seem to succeed because they are already pre-adapted from a similar
> environment
> to compete with the natives, but without the parasite and predator
> load that
> they conveniently left behind in the old country, so they out-compete
> the local
> species. You could argue that the trees are under-exploited in
> Patagonia or
> Cape Breton by beavers and gypsy moths respectively, but then the
> invaders
> seriously destabilized the existing ecology by killing off lots of the
> resources, trees, so it is not a benign result. For plants, a classic
> case
> would be the prickly pear imported into Australia, which originally
> had no
> parasites to control it until the moth (Cactoblastis?) was introduced
> for this
> purpose.
>
> I'm not an ecologist, but some on NNS are. Maybe someone else (or you
> yourself)
> can come up with an actual example of your point, where you seem to
> claim that
> an invading species can come in and wax fruitfully in a new zone without
> damaging the ecosystem, merely by utilizing an unused resource? Maybe
> I'm
> missing something.
> Steve, Halifax
>
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