Kelly and others interested:
The silence is relatively deafening, eh? I got a nice list of references
off-list, and the Crants post was pretty good, but for the most part this
subject appears to be on the taboo side. One of the references I tracked
down from the list was so scholarly I could barely make heads or tails of
it, so it's no wonder it hasn't taken off like an alien-grass-fire. Still, I
applaud the authors for the attempt to resolve this knotty, weedy issue.
I failed to understand Professor Lewontin's definition too, and wish someone
could provide an example. A study from a few years back indicated that the
Torrey pine populations on the mainland and Santa Cruz Island are
genetically different from each other but that each population is
genetically uniform. The seeds are not sterile, however, and I don't know
enough to say what the barrier to crossing might be. However, the mainland
population seems to have no problem with recruitment, particularly following
fire, and, if I recall correctly, within the undisturbed understory. I do
not understand how, even if such a phenomenon exists somewhere (anyone,
please educate me), how that constitutes "weediness." Even in the popular
sense, I've always understood weedy to mean quite the opposite.
The challenge, I suggest, is to overcome the semantic tangle, first in the
ecological sense, then in the popular sense. The first hurdle, I suspect, is
to simply declare the obvious but neglected fact that ecology is distinctly
different from horticulture, on the simple grounds that ecosystems are
changing phenomena that are independent of control, while gardening,
landscaping, farming, and in some cases even forestry, are dependent upon
control.
In some states, "official" weed lists contain indigenous species because
they "invade" their farmed, ranched, or landscaped habitats. Ironic, eh?
Ecologists term "escapes from cultivation" as invaders. It's the old
anthropocentric versus nature-centric dichotomy "all over again," but I
suggest that it could be resolved if the differences were simply recognized
rather than used in polemics, ad infinitum, with no real resolution.
The terminology may be sorting itself out to some extent, such as "weed"
being more prevalent among the various branches of horticulture and "alien"
being more common in ecology. In my own simple lexicon, I have developed the
habit of following this most of the time, but I should be more careful.
"Colonizing species" was once popular, and still might be useful as an
umbrella term under which the other two terms could fit, so I sometimes use
it in that manner.
I have no problem with "weed" meaning "a plant out of place" or some such
definition, with it being reserved for the branches of horticulture.
While all plants "colonize," the term in common scientific usage has most
often been used in connection with mostly alien (non-indigenous) species
colonizing disturbed sites, with "invasive" being commonly used to refer to
those species which colonize undisturbed habitats. I would add, however,
that the level of "aggression" with which a species "invades," and the
degree to which it remains and displaces indigenous species (which
co-evolved and have developed mutual dependencies with other species) should
be considered.
These boundaries may not be perfectly "clean," but I submit that the
exceptions tend to be definable in context with the necessary amount of
explanation of the fine points taking up the slack.
I invite further discussion on this idea, and am particularly interested in
arguments to the contrary. I would be most happy to follow a superior
convention, particularly one that is useful as both scientific and "popular"
terminology. Additionally, I would be delighted to be specifically reassured
that there is no need for any such consistency, and/or that a longer list or
proliferation of terms is a better idea than having ecologists and other
rally 'round some consistent bag of clear terminology.
In the absence of any such correction, I will consider this to be the
"final" word on the subject (which all others will, of course, immediately
adopt as THE standard). Worldwide, of course.
WT
I don't think Nature gives a damn, but in order to communicate CLEARLY, I
think we should, and we should be more disciplined in how we communicate.
The test of clear communication is whether or not everyone understands what
one is talking about. It is not necessarily about some largely irrelevant
degree of precision--even in mathematics, for example, pi is commonly
truncated at the number of decimal places relevant to the context. I quite
agree with Stettner's last statement that the terminology is a human
invention. Se la va sans dire!
----- Original Message -----
From: "Kelly Stettner" <[email protected]>
To: <[email protected]>
Sent: Tuesday, April 13, 2010 8:27 AM
Subject: Re: [ECOLOG-L] Weeds and Invasives, Arguments and Distinctions
Wayne, you bring up a "thorny" issue...one of my favorite conundrums. A weed
by any other name, eh? From the wiki entry you provided, I see many
references to weeds as "undesirable" or "nuisance" plants with little use to
humans. I agree that "the term weed in its general sense is a subjective
one, without any classification value, since a 'weed' is not a weed when
growing where it belongs or is wanted." (Emphasis mine)
For instance, dandelions are unwanted nuisances when a person wants a
well-manicured, well-behaved lawn. To the wine-maker and the child, however,
dandelions are very desirable. Japanese knotweed is a scourge to many who
own river-front property infested with the tall plant; bee-keepers, however,
are very grateful for their late-season profusion of blooms providing needed
nutrition for their fuzzy little wards. Weediness, it seems, is in the eye
of the beholder.
I am fascinated by Prof. Lewontin's definition of a weed as a plant that
creates "environmental conditions in which it cannot reproduce." Pine trees
as weeds...Interesting concept! By that definition, a pine grove, left
undisturbed by fire or man's axe, would die off of its own accord? Would
that apply to all evergreens, or just pines? I'll have to look him up and
read some of his research, see if I can delve deeper.
I know there has been a concerted effort over the past few years to define
"invasive" as well; not sure if that effort is making any headway or if it,
too, is somewhat subjective. I, for one, consider poison ivy to be both
invasive and noxious, but it's only noxious to humans, apparently. Were we
covered in fur or feathers, the urushiol oil could not contact our tender
skin and cause the burning rash so famous among hikers and Boy Scouts. By
the same token, my daughter loves Creeping Charlie or Ground Ivy, and can
spend hours nibbling the delicate little purple flowers for their minty
essence.
There is also the question of abundance and "aggressiveness." What some call
"aggressive" growth could be seen as "successful adaptation to environmental
pressures," could it not? Japanese knotweed is a "first responder," so to
speak, in volcanic situations in Japan, being one of the first (if not THE
first) plant to re-colonize after a lava flow. It was introduced to the US
as an ornamental at first and then as a stream bank stabilizer to hold soil
in place. It has since spread very successfully all over the country. There
are critters that use it (bees, ants, other insects) and it is edible when
very young and relatively tender.
So I guess that, ultimately, we ought to pony up and admit that most
definitions of "weed" and "invasive" are going to distill down to what we
humans value and desire. And that our needs, values and desires are going to
change over time.
Respectfully,
Kelly Stettner
Black River Action Team
www(dot)BlackRiverActionTeam.org
blackriverclea...@yahoo(dot)com
Date: Sun, 11 Apr 2010 22:49:58 -0700
From: Wayne Tyson <[email protected]>
Subject: Plants Colonizing Weedy or Ruderal or Invasive Arguments and
Distinctions?
Ecolog:=20
Fools rush in where the exalted fear to tread, but here goes:
A certain certainty seems to persist around the subject of colonizing
species or "weeds." I have visited a couple of sites (one highly
professional, but still confusing) which contain what appear to me to be
quaint statements, hidden amongst the valid phrases.
http://en.wikipedia.org/wiki/Weed and its associated pages, for example,
may be sowing the seeds of confusion far and wide.
I do not know how widespread these alien, ruderal, or feral ideas are,
or whether I am persistently misinformed. It seems that with respect to
"weed" in particular, authors prefer to "hedge" rather than clarify or
qualify--at least sufficiently, in my view. An ecological view seems to
be lacking, even for "balance."
I do not want to lead others down the garden path, but I think is it
high time this confusion was clarified and settled, at least to the
point where differences are made distinct.
Are you similarly disturbed or confused? Would you please participate in
getting to the root of the matter, right here on Ecolog?
Thank you all for your help.
WT
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