[RWG] [APWG] Allelopathy knowledge can save time when weeding+restoring areas
Wayne Tyson
landrest at cox.net
Wed Sep 7 11:40:50 CDT 2011
Y'all,
I'm amazed at how close Dominic and I are on most of this.
I never got to the bottom of the Muller-(forgot the name; from Berkeley)
controversy, so my "knowledge" about it is small. I always wanted to know
more detail about the herbivore evidence, and particularly wanted to know
about trampling and other rabbit-maze effects.
I came around to the idea that stress was a bigger help than hindrance in
the development of restored ecosystems, largely because that's how
indigenous ecosystems work ("best," from the point of view of real--as
opposed to arbitrary--restoration objectives). The details should be obvious
to any ecologist, but it is amazing how few embrace the concept (beyond
subordinate head-bobbing).
Almost forty years on, I suspect a number of factors were responsible for
the phenomena I described with respect to weed suppression. Their brief
appearance with slightly increased vigor in the second year and their
subsequent steady decline began with N-sequestration and ended with the
plain old survivorship curve having to do with light deprivation and other
micro-habitat changes. In ecosystem restoration we are not seeking
uniformity, and uniformity should not be a part of our tool-kit.
I do not believe grasslands, particularly coastal prairie habitats (truly
historic grasslands and grassland/shrublands) are particularly difficult to
restore, as long as our thinking is not too light-deprived. I do not believe
that we, as ecosystem restoration practitioners, actually restore anything;
all we can hope for is that we can facilitate natural processes--largely by
staying out of the way. This does not mean not to take any action, it means
to make sure that the actions we take are more related to that end than,
say, lining our pockets more thickly.
Take straw for example. It makes nice straw-men, and it can be especially
useful as a microhabitat modifier, but it is not without its costs and
disadvantages. Weighing those pros and cons--aye, THERE'S the RUB!
As Maze points out, there's no recipe. CONTEXT is EVERYTHING. This confounds
ecologists and others who try to mess with ma Nature--for her own good, of
course. The variables are overwhelming.
WT
----- Original Message -----
From: "Maze, Dominic" <Dominic.Maze at portlandoregon.gov>
To: <apwg at lists.plantconservation.org>; <rwg at lists.plantconservation.org>
Sent: Friday, September 02, 2011 1:05 PM
Subject: Re: [APWG] Allelopathy knowledge can save time when
weeding+restoring areas
>
> Hello all,
>
> All of this discussion reminds me of both Richard Halsey's paper from
> 2004, (Jour. of Torrey... 131(4))and my undergraduate plant ecology course
> at UCSC discussing the classic false correlations attributed to
> allelopathy in Cal. coastal scrublands by, I think, Muller. As I remember
> it, there was less growth and recruitment of forbs and grasses under
> certain shrubs. Must be allelopathy, right? However, those certain shrubs
> also provided preferred habitat for certain herbivores that like to eat
> those forbs/grasses and didn't want to get eaten, themselves, by hawks and
> other predators.
>
> Having lived and worked in restoration in Central Cal., coastal prairie,
> oak, shrub, etc., for over a decade before moving to Oregon (and being
> intimately familiar with Arastradero Preserve area, Los Gatos and Aptos,
> to boot), I am certainly familiar with the difficulty in "restoring"
> grasslands. Beyond the hard to believe (not to say, not true) claims
> about 99.5% native cover on one or two properties in Aptos or Los Gatos, I
> have heard nothing about a real experimental design: data collection,
> replication, etc.; just a case study of a presumably massive input of
> resources into one or two persons' properties who have the resources at
> their disposal to pull this off (hey, we're talking Los Gatos and Aptos,
> here). If that is the scenario that is responsible for 99%+ native cover
> and an unknown Gnaphalium sp. reappearing (which I'd like to know more
> about, as well), then yes, I would love to see these efforts replicated
> across all Western grasslands!
>
> I have heard analogies about antibiotics and poker to support broad
> claims and anecdotal evidence, including ex situ pictures and as far as I
> can tell an arbitrary ranking system of plant "power", to "prove"
> effective use of assumed allelochemicals to potentially restore
> grasslands. Does a layer of Nasella straw inhibit weed germination and
> growth? Does a layer of bark mulch? Packing peanuts? As Wayne Tyson
> points out, he doesn't just assume any factor is responsible for that
> first successful restoration of his. Did it look like allelopathy? Yeah,
> it did! Was it allelopathy? No one will ever know.
>
> I believe that "chemical warfare" between plants is proven in some
> interactions and feasible in most; heck, it is obvious many plants use
> chemicals to not get demolished by higher trophic levels (and basic tenets
> of plant pathology and classical biological control support this). But if
> I am to receive sensational (and admittedly, intriguing) claim after claim
> in my inbox about restoration using, as far as I can see, either concerted
> multi-year efforts on one property or expensive restoration protocols
> involving native straw, etc., then I'd like to see some scientific
> methodologies discussed and real proof. I have always been suspicious of
> "recipe" restoration ("if we could just burn the prairies like the Indians
> did, it'll all come back!"). Heck, maybe my own past difficulties (and
> hard-won successes) in restoration make me bitter and less likely to
> believe others' seemingly easily won successes; but as Tom Cruise said in
> that awful and otherwise forgettable movie, "Show me the money!" That
> said, keep up the good work, everyone out there trying to answer these
> questions attempting to conserve and restore what we have left. I'll take
> any answer off the air.
>
> Sincerely,
>
> Dominic Maze
>
> -----Original Message-----
> From: apwg-bounces at lists.plantconservation.org
> [mailto:apwg-bounces at lists.plantconservation.org] On Behalf Of Craig
> Dremann - Redwood City Seed Company
> Sent: Friday, September 02, 2011 10:55 AM
> To: apwg at lists.plantconservation.org; rwg at lists.plantconservation.org
> Subject: [APWG] Allelopathy knowledge can save time when weeding+restoring
> areas
>
> Dear All,
>
> Thanks for your email. I got a couple of offline questions about knowing
> the id of the active herbicide chemicals in the plants, and why use 2
> inches of the Stipa straw? I am posting my reply, as it might be of
> interest to all:
>
> Even if we do not know exactly what chemicals in these plants are working
> against the weeds, if we figure out how to use them to our advantage,
> perhaps they could save a huge amount of time and labor for all of our
> weed management or restoration project?
>
> If we think of these chemicals as antibiotics, and we are applying them to
> a macroscopic petri dish, then they could be visualized that way.
>
> Instead of waiting for someone to id the chemicals that were active before
> I could use them, I thought it was more important to invent a method to
> measure the chemical effects of one plant against another, and give each
> plant a number 1-100 to indicate their power?
>
> Then it becomes like a poker game, where a 8 beats a 3 for example.
>
> I am using 2 inches of Stipa mulch, for its long lasting effect at the
> site, because of the multi-layered dormant weed grass seeds in the soil.
>
> On the site in Palo Alto, there is a 150 year history of the introduction
> of weed grasses buried in layers like an archaeological site, with the
> most dominant grass suppressing the germination of the dormant seeds of
> the next, and so forth, and there are at least 5 layers out there.
>
> So let's say from the pictures at http://www.ecoseeds.com/arastradero.html
> that wild oats is the most dominant layer, so when you suppress the wild
> oat seeds from germinating, then the ripgut grass seeds get to germinate.
> Then when you suppress the ripgut, the Blando brome is allowed to
> germinate.
>
> When you suppress the Blando, the Perennial ryegrass may by your final
> layer of weed grasses. But wait--you are not done yet with the dormant
> weed seeds!
>
> Now all the different annual and biennial forb weeds that were suppressed
> by all the grasses will want their turn to sprout, once the suppression of
> the allelochemicals of the grasses has been released.
>
> Before I begin any large scale project, I want to know accurately what the
> allelochemical strength for each weed species and each native species on
> the site. Then as the team captain for the natives, I know which natives
> I should pick for my team to beat the exotics.
>
> For the cheatgrass, just planting back the local native grasses will
> permanently take care of that weed nicely, as you can see my photos from
> the 600 acres that were planted in the Great Basin at
> http://www.ecoseeds.com/greatbasin.html
>
> I am going to look forward to others reading these two lists, who will
> experiment with this idea over the next year, and we should share our
> results next summer, and see what strong allelopathic native and exotic
> plants we have come up with in the different parts of the country?
>
> Sincerely, Craig Dremann (650) 325-7333
>
>
>
>
>
>
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