Warren/Ecolog:
To further clarify and more fully respond to this post, I do agree that a
plant with a larger total biomass, especially with respect to
transpirational surface, will "use" more water than smaller plants (less
total biomass) with less transpirational surface. However, since much of a
larger plant's total biomass is represented by a fraction (wood, bark,
cortex, etc.) I speculate that, to make an accurate and relevant comparison,
adjustments will accordingly need to be made if one is to asses the
"water-hog" quotient of the two categories so the potential for an "apples
to oranges" issue is minimized. For example, is it standard procedure in
such cases to use the area coverage of, say, junipers and grass/forb/shrub
coverage when estimating transpiration (and evaporation?). How much more
does a juniper covering the same area as the grass/forb/shrub category
transpire in a year or seasonal cycle and in "luxury" and high-stress
conditions, and are such data normalized over a longer period (say, a few
years)? Is wind velocity a relevant factor? The amount of solar radiation
(sun/shade) effects? For example, I speculate that the wind speed and
frontal area of junipers and hence transpiration/evaporation may be greater
than the grass/forb/shrub component, but, on the other hand, the windbreak
and shade effects might offset those factors to a greater or lesser
degree--but by how much, and how significant?
Has grazing and associated soil disturbance been ruled out and fire
suppression "ruled in" as a cause of the juniper "intrusion?"
I agree that juniper seeds are not dispersed via cow pie; my suspicion
was/is that the added nutrients, dispersal of Bromus tectorum and other
species introduced largely by cattle, and "safe site" influence of cow pies
might have had direct and indirect influence upon soil moisture and
groundwater recharge, but I was not clear about that.
I ask these questions because I do not know what procedures are used, so
Warren and/or others can perhaps fill me in.
Thank you, Warren, for the link/reference.
WT
----- Original Message -----
From: "Warren W. Aney" <a...@coho.net>
To: <ECOLOG-L@LISTSERV.UMD.EDU>
Sent: Monday, September 12, 2011 11:11 PM
Subject: Re: [ECOLOG-L] a non Ivory Tower view of invasive species
Wayne, it would seem to be as simple as this: a stand of junipers has
greater biomass and a deeper root system than a flora composed of grasses,
forbs and scattered shrubs. As a result the stand of juniper transpires
more water from more levels than its counterpart biota. However, the
observed effect of juniper removal on springs and streams is primarily
anecdotal, as you said.
Oregon's Great Basin ranges were heavily overgrazed starting way back in the
late 19th century. The increase in juniper cover has occurred since then,
primarily as a result of reduced fire carrying forage species.
You can find out much more than you probably want to know about this in the
2005 Oregon State University Technical Bulletin 152, Biology, Ecology, and
Management of Western Juniper.
http://www.sagebrushsea.org/pdf/Miller_et_al_Juniper_Tech_Bulletin.pdf
This publication will answer your questions about pre-fire-exclusion stand
characteristics, management practices, and causes for increased juniper
recruitment. It will informs us that cow pies have little or no effect -
juniper seeds spread by birds, not cattle.
Warren W. Aney
Tigard, Oregon
-----Original Message-----
From: Wayne Tyson [mailto:landr...@cox.net]
Sent: Monday, 12 September, 2011 19:28
To: Warren W. Aney; ECOLOG-L@LISTSERV.UMD.EDU
Subject: Re: [ECOLOG-L] a non Ivory Tower view of invasive species
Warren and Ecolog:
Well, Warren, I guess I'll have to take your word for it. You've got more
experience with that area than I do, but I would still like to know more
about the theoretical foundations and evidence to justify some of those
conclusions. And, I'm concerned about the actual costs and benefits to
wildlife as well as cows. To me, that area shouldn't have a cow on it, but
certainly not a subsidized cow on a subsidized "range." And I come from a
cow background, so I'm not prejudiced; I had a Hereford bull for a 4-H
project, so I'm not insensitive to "ranchers" either. But I have seen plenty
of cow-burnt "range" in the Intermountain West.
I've heard the same "water-hog" story about pinyon pines and other "brush"
all over the western US. I've heard the restored spring and streamflow
stories too, but haven't seen evidence beyond anecdotal stuff. However, you
know me, I think that anecdote is the singular of data. But correlation,
again, is not necessarily causation. I'm still skeptical, but holding any
"final" judgment in reserve.
I do agree that "nothing" grows under junipers, but out beyond the drip line
it's a different story, at least where I've observed it elsewhere (I wasn't
that carefully-observant at Steen's). I don't doubt the stemflow part
either, but it's not uncommon for plants to shade out other plants; this
doesn't mean that said "parched mini-desert" is a serious problem in the
context of the ecosystem--or does it? But the channeling down into the
ground works to the benefit of the juniper--ain't that the way it's supposed
to work? What is the penetration profile like in the absence of the juniper?
What's the ratio of annual unit biomass production to water consumption for
junipers? For the "replacement" vegetation? Has it been demonstrated that
groundwater recharge is more effectively intercepted by junipers than, say,
grasses. The former have deeper, ropier root systems than grasses that mine
the capillary fringe and other water on its way down, but enough to shut off
springs and stop streamflow? It seems to me that any given site has a given
effective carrying capacity that is going to limit vegetation growth
accordingly, no matter what the (natural) vegetation is. The water may have
a better chance of percolating past the junipers than the grass, no? The
junipers have a limited capacity (and a limited need) for water; the grasses
will increase transpiration surfaces much faster in response to water.
What were pre-fire-exclusion stand characteristics? Are management practices
aiming for that, or for some other target? How much increased juniper
recruitment occurred as a result of fire exclusion rather than some other
cause, such as livestock-induced soil disturbance? Do cow pies have any
effect, etc?
Now I guess we have to add "intrusive" to our list of terms? But really,
Warren--crying cowboys? Is that fair?
WT
----- Original Message -----
From: "Warren W. Aney" <a...@coho.net>
To: "'Wayne Tyson'" <landr...@cox.net>; <ECOLOG-L@LISTSERV.UMD.EDU>
Sent: Monday, September 12, 2011 3:44 PM
Subject: RE: [ECOLOG-L] a non Ivory Tower view of invasive species
Yes, Wayne, the BLM is cutting down "big junipers" as you saw -- 100 years
of fire protection means we now have some pretty good-sized junipers in the
areas that once burnt over. However, the BLM is not cutting down the really
big "grandfather" junipers growing on rims and rocky ridges where wildfires
did not reach or burn hot enough to kill these old junipers.
Regarding water and vegetation effects, junipers are water hogs and
vegetation excluders. The ground under a big juniper tends to be void of
grasses, forbs and shrubs. That's because the juniper not only mines the
deep water, its canopy also collects rainwater and channels it down the
trunk into the ground, creating a parched mini-desert where other species
are inhibited from growing.
My son tells an anecdote from when he was a Forest Service district ranger
on the east (Great Basin) side of the Fremont-Winema National Forest: He
took a senior rancher to see an area adjacent to his ranch property where
they had been removing intrusive juniper from a draw leading into the
Chewaucan River. When the rancher saw rejuvenated springs he teared up,
saying "I remember seeing those springs go away many years ago and I thought
I'd never see them flowing again."
Warren W. Aney
Tigard, Oregon
-----Original Message-----
From: Ecological Society of America: grants, jobs, news
[mailto:ECOLOG-L@LISTSERV.UMD.EDU] On Behalf Of Wayne Tyson
Sent: Monday, 12 September, 2011 13:08
To: ECOLOG-L@LISTSERV.UMD.EDU
Subject: Re: [ECOLOG-L] a non Ivory Tower view of invasive species
All:
The BLM has a "demonstration" project on Steen's mountain, complete with
plasticized photos and text explaining that fire suppression was the culprit
in the juniper "invasion," but my bias tends to line up more with Hohn's.
However, I suspect trampling and hoof-dragging (soil disturbances) are more
likely to be primary factor, borne more of gut feelings than evidence. The
BLM PR discusses the comparative effects of various treatments, but the bias
seems to be pretty much as Hohn describes.
Back in 1980, I used the field-trial approach to "test" various treatments
for grassland restoration. One of the results showed that evaporative losses
went up, apparently drastically, as the clayey soil developed large
desiccation cracks quickly, while the uncleared plots did not crack until
much later in the dry season. If the cracks are deep enough and swelling
doesn't close them too fast, there might be an advantage to the cracks as a
means of depositing free water (especially in low-volume precipitation
events) at depth rather than depending upon percolation alone. This sort of
thing cries out for more and better research than we had the budget to do.
Based on what I have read and heard over the years, I suspect that
plant-soil-water relations, especially in wildland soils, is not
well-understood by most researchers. The more certain a researcher is
concerning such conclusions, the more I tend to consider them suspect.
I think that a lot of range managers are shooting themselves in the foot by
cutting down big junipers (as has been done at Steen's Mountain). First,
interception of solar radiation tends to reduce evaporative loss. Second,
junipers and other woody plants of semi-arid and arid regions tend to be
fairly efficient in terms of "water use." Third, grasses tend to mine water
from shallow depths and transpire more (higher ET?) from the first, say,
meter or less of soil, thus intercepting percolating water, especially in
heavier soils, possibly or probably reducing rather than enhancing
groundwater recharge. Fourth, I suspect that the marginal "improvement" in
forage production is a snare and a delusion; nobody seems to check the
alternative of a mixed stand, so there is no comparative basis for any such
conclusions apart from intuitive inference. Fifth, heterogeneous sites are
more resilient than more homogeneous ones; the big, old junipers (ironically
far older than the acknowledged beginning of fire suppression) shade areas
where grasses tend to remain active longer as the season advances, providing
more palatable forage as well as providing for wider reproduction potential
via zones of seed production when the more open areas die or go dormant,
resulting in diminished seed production or "crop" failure (provided the
stock has been taken off soon enough to keep the seeds from being eaten
before maturity). Sixth, the old junipers provide stock shade and wildlife
cover. There may be more, but that's what comes to mind at the moment.
If managers want to control the juniper invasion, why not kill the trees
that truly represent the invasion, i.e., the younger seedlings, saplings,
and smaller trees rather than the ones they must acknowledge existed prior
to the "invasion?"
As usual, I look forward to alternative evaluations of the evidence,
including speculation with a sound theoretical foundation.
WT
PS: I'd like to see some conclusive evidence that, in the long-term,
exclusion of livestock from cheatgrass areas would not result in reduced
cheatgrass populations. The restoration process could be speeded up by
planting colonies of indigenous grasses and perhaps other species (as
propagule-generators and for site heterogeneity) consistent with comparable
sites without heavy cheatgrass populations.
----- Original Message -----
From: Charlie Hohn
To: Wayne Tyson
Cc: ECOLOG-L@listserv.umd.edu
Sent: Monday, September 12, 2011 10:06 AM
Subject: Re: [ECOLOG-L] a non Ivory Tower view of invasive species
Native invasives are an important thing to acknowledge, because again the
issue is not where plants are native to, but if they are invasive. Native
invasives are necessarily behaving in this way due to changes in their
environment (I think in the juniper's case it has to do with grazing,
right?)... and in these cases - as well as with many non-native invasives,
it makes sense to deal with the problem by addressing the changes in the
environment (adopt better grazing practices, fire management practices, or
whatever the case may be). However, I do think there are some invasive
organisms that would be a problem even WITHOUT all these other human
disturbances (for instance, cheatgrass)... that invade undisturbed areas and
'crash' ecosystems without being caused by environmental changes. I think
that is the main reason to differentiate native invasives from introduced
ones.
On Mon, Sep 12, 2011 at 9:41 AM, Wayne Tyson <landr...@cox.net> wrote:
Warren (and others), how might the juniper "invasion" on Steen's
Mountain (or other "invasions" of indigenous species, particularly dominant,
long-lived indicators) fit into this discussion?
WT
----- Original Message ----- From: "Warren W. Aney" <a...@coho.net>
To: <ECOLOG-L@LISTSERV.UMD.EDU>
Sent: Sunday, September 11, 2011 9:08 PM
Subject: Re: [ECOLOG-L] a non Ivory Tower view of invasive species
I was speaking from a contemporary perspective, Manuel. From a very
long
term perspective perhaps we can say that a species that somehow
translocated
into another ecosystem may have initially disrupted that ecosystem but
after
a few thousand generations the species and the ecosystem evolved
together to
form a coherent and mutually productive stability. There is a hypothesis
that Native Americans disrupted the American ecosystems resulting in the
extinction of several large mammal species shortly after their arrival.
But
after a few thousand generations it appears that they became a component
of
the American ecosystems, sometimes managing certain ecosystem elements
to
their benefit but certainly not disrupting and degrading these systems
to
the extent that Euro-Americans did (and continue to do so).
Taking your island fauna example, consider the Galapagos finches.
Charles
Darwin concluded that there was probably a single invasion of a finch
species eons ago, but these finches evolved into different species so as
to
fill various ecological niches, resulting in a diverse and stable set of
finch-inhabited ecosystems. Certainly introduced rats could also
eventually
evolve along with the ecosystems to become a stable component. But in
the
short term that ecosystem is going to be disrupted, and in the long term
that ecosystem is going to be a somewhat different system. We humans,
as
"overseers" have the ability and duty to evaluate that current
disruption
and that future potential. There are those of us who say "let nature
take
its course" and there are those who say "manage for human values" - I
say we
should be following the axiom of Aldo Leopold: "A thing is right when it
tends to preserve the integrity, stability, and beauty of the biotic
community. It is wrong when it tends otherwise." We need to evaluate
and
manage invaders with that axiom as our beacon.
Warren W. Aney
Tigard, Oregon
_____
From: Manuel Spínola [mailto:mspinol...@gmail.com]
Sent: Sunday, 11 September, 2011 04:54
To: Warren W. Aney
Subject: Re: [ECOLOG-L] a non Ivory Tower view of invasive species
Hi Warren,
Take an island, you have "native" birds and later in time you have black
rats that you consider invaders, but why those "native" birds are in the
island, they needed to be invaders at some point in time.
If Homo sapiens originated in Africa, from where the native Americans
are
from?
Best,
Manuel
2011/9/10 Warren W. Aney <a...@coho.net>
There can be a meaningful ecological difference between an organism that
evolved with an ecosystem and an organism that evolved outside of but
spread, migrated or was otherwise introduced into that ecosystem. An
organism that evolved with an ecosystem is considered a component that
characterizes that ecosystem. An introduced organism that did not
evolve
with that ecosystem should at least be evaluated for its potential
modifying
effects on that ecosystem.
Am I being too simplistic?
Warren W. Aney
Senior Wildlife Ecologist
Tigard, OR
-----Original Message-----
From: Ecological Society of America: grants, jobs, news
[mailto:ECOLOG-L@LISTSERV.UMD.EDU] On Behalf Of Manuel Spínola
Sent: Saturday, 10 September, 2011 12:22
To: ECOLOG-L@LISTSERV.UMD.EDU
Subject: Re: [ECOLOG-L] a non Ivory Tower view of invasive species
With all due respect, are not we all invaders at some point in time?
Best,
Manuel Spínola
2011/9/10 David L. McNeely <mcnee...@cox.net>
---- Matt Chew <anek...@gmail.com> wrote:
> We can compose effectively endless lists of cases where human agency
has
> redistributed biota and thereby affected pre-existing populations,
> ecological relationships and traditional or potential economic
> opportunities. Those are indisputable facts.
The House Sparrow is in North America by human hand.
> But what those facts mean is disputable.
House sparrows are in serious decline in Europe, probably as an
unintended
consequence due to human actions.
>
> I see effects; they see impacts.
> I see change; they see damage.
Many people see a need to eradicate non-natives. At the same time,
many
people see a need to preserve natives.
With regard to the house sparrow ------ hmmm......... .
Where does the "arms race" that Matt mentioned further along in his
post
lead?
mcneely
>
--
*Manuel Spínola, Ph.D.*
Instituto Internacional en Conservación y Manejo de Vida Silvestre
Universidad Nacional
Apartado 1350-3000
Heredia
COSTA RICA
mspin...@una.ac.cr
mspinol...@gmail.com
Teléfono: (506) 2277-3598
Fax: (506) 2237-7036
Personal website: Lobito de río
<https://sites.google.com/site/lobitoderio/>
Institutional website: ICOMVIS <http://www.icomvis.una.ac.cr/>
--
Manuel Spínola, Ph.D.
Instituto Internacional en Conservación y Manejo de Vida Silvestre
Universidad Nacional
Apartado 1350-3000
Heredia
COSTA RICA
mspin...@una.ac.cr
mspinol...@gmail.com
Teléfono: (506) 2277-3598
Fax: (506) 2237-7036
Personal website: Lobito de río
<https://sites.google.com/site/lobitoderio/>
Institutional website: ICOMVIS <http://www.icomvis.una.ac.cr/>
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--
============================
Charlie Hohn
Recent Graduate
Field Naturalist Program, Department of Plant Biology
University of Vermont
naturalist.char...@gmail.com
slowwatermovement.blogspot.com
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