[RWG] FW: [APWG] Allelopathy knowledge can save time when weeding+restoring areas

[Maze, Dominic]

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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