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> herbicides and wipe o
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Japanese Knotweed at McNabs
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From: dwebster@glinx.com
To: naturens@chebucto.ns.ca
Subject: Re: [NatureNS]Invasive aliens: was re unauthorized vs. OK plants l=
ists
Date: Sun=2C 31 Oct 2010 21:20:48 -0300
HI Jim & All=2C Oct 31=2C 2010
Executive summary:=20
I can not think of one non-native plant that has caused a serious probl=
em in Eastern Canada. Some=2C for a few years=2C may locally overwhelm nati=
ve plants. But sometimes native plants overwhelm other native plants.=20
=20
The longer version:
Labels tend to cloud rather than clarify matters=2C as I will discuss l=
ater. First though one should get the history correct.
=20
Based on Gray' s Manual (7 th ed=3B 1908)=2C Purple loosestrife (as Lyt=
hrum salicaria and as L. salicaria var. tomentosum) must have landed in Nor=
th America way before 1900. By the time this 7 th ed. was compiled and prin=
ted=2C typical PL was present in N.E.=2C 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. =20
=20
Someone who has access to earlier editions of Gray's manuals and/or Har=
vard/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 ornam=
entals.=20
=20
The 7th ed. says L. salicaria is 'local'. In the 8th ed. (1950) this is=
expanded to 'locally abundant=2C often too aggressive in choking out nativ=
e vegetation.' .=20
=20
LABELS: Labels are fine if in=2C e.g. ecology=2C if they are used to charac=
terize 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 init=
ially replaces the mostly herbaceous ground cover of abandoned farmland=3B =
the older trees being predominantly Spruce (favoured by exposed mineral soi=
l) and the later arrivals being predominantly Fir (favoured by litter).=20
=20
I suppose from the viewpoint of these displaced shade-intolerant herbac=
eous plants=2C these Spruce could be considered "Invasive" but more objecti=
vely they are just players in a process of secondary succession.=20
=20
And secondary succession never sleeps. Shortly after crustose lichens e=
stablish borders they are swamped by foliose lichens that prosper at the ed=
ges and decline in the middle. And comparable processes of encroachment=2C =
prosperity at the fringes with stagnation in the interior can be seen in th=
e vegetation of barrens=2C bogs and even in woodland (esp at the level of a=
ir photographs). =20
=20
But labels=2C such as "Invasive Alien" that are assigned on the basis o=
f prejudice or labels that have emotional overtones can obstruct clear thou=
ght and consequently belong more in the realms of politics or propaganda th=
an in natural history or biology.=20
=20
In many and perhaps all cases the question is not "Why did this plant b=
ecome invasive ?" but "Why did it become fashionable to call this plant inv=
asive ?" Or even "Why did it become fashionable to call alien plants that =
do unusually well here invasive ?"=20
=20
Was it to drum up support for field research ? [It is unfortunately lik=
ely 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 cri=
sis in sight then it will be expedient to invent some. Surviving cultures a=
re those that adopt the trappings that facilitate survival.]
=20
Or was it to solicit contributions to save... whatever fits...=3B our =
native pristine wetlands...the Acadian Forest... or at least cover the cost=
of collecting the contributions ?=20
=20
Proceeding now from the general to the particular=2C if we are to " or=
dinarily rule against importation of any non-native species. " I guess this=
means we should=2C while there is still time before these non-native speci=
es become vicious=2C wipe out the Sable Island Ponies and of course outlaw =
most agricultural crops and livestock ( e.g. horses=2C cattle=2C sheep=2C g=
oats=2C asparagus=2C potatoes=2C oats=2C barley =2C wheat=2C beets=2C carro=
ts=2C tomatoes=2C apple=2C pear=2C ....and rabbits=3B especially rabbits) a=
nd=2C to be on the safe side=2C we should bring back non-selective herbicid=
es and wipe out the mostly non-native vegetation of lawns=2C ornamental shr=
ubs and flower gardens.=20
=20
And if we are going to "ordinarily rule against importation of any non=
-native species"=2C and bearing in mind that native species are already her=
e and thus do not need to be imported=2C I guess this means that we should =
close the border to all trade involving plants (or animals by extension). =
=20
=20
Hopefully those non-native plants that travel by wind=2C water=2C flesh=
or fowl will do the right thing and bail out before they cross the border=
.=20
=20
But on the other hand=2C perhaps those very aggressive invasive species=
will be inconsiderate enough to cross the border anyway. In fact that migh=
t be a practical working definition of this class. Therefore=2C on this bas=
is=2C all plants should be on the white list.=20
=20
Yt=2C Dave Webster=2C Kentville
----- Original Message -----=20
From: James W. Wolford=20
To: NatureNS=20
Sent: Monday=2C October 25=2C 2010 5:25 PM
Subject: [NatureNS] re unauthorized vs. OK plants lists
Randy's example of purple loosestrife is an instructive case in point. As =
I understand it=2C p. l. was imported into North America way back in the ea=
rly 1900s? 1930s? or even before that=2C but for unknown reasons didn't bec=
ome a large problem and invasive with detriment to native plants and marshe=
s until several decades passed. My impression from reading is that this is=
a fairly general phenomenon regarding imported alien species=2C so that it=
's difficult to predict which plants will turn out to be invasive. Thus th=
e general principle that all jurisdictions need to=2C as a rule=2C untilize=
precautionary skepticism and ordinarily rule against importation of any no=
n-native species. Cheers? from Jim in Wolfville
Begin forwarded message:
From: Randy Lauff <randy.lauff@gmail.com>
Date: October 25=2C 2010 9:31:31 AM ADT
To: naturens@chebucto.ns.ca
Subject: Re: [NatureNS] White list of authorized plants
Reply-To: naturens@chebucto.ns.ca
I think the point of a white list=2C as opposed to a banned list is relativ=
ely straight forward=2C actually.=20
I do take Marty's point that with huge shipments of goods=2C and also peo