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

Wed Sep 7 16:33:04 CDT 2011

Dear Dominic and All,

Thanks for your email.  I will put my replies after your questions:

DOMINIC:    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 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.

REPLY: Yes, I frequently see that shrub-edge effect at the shrub/grassland
interface, but that is of no practical use when restoring grasslands, or
when planting a local native plant in the place of a weed, as a permanent
replacement.

It is absolutely necessary to invent a method to measure the allelopathic
chemical strength of each plant, for both the weeds and the local native
that you want to utilize.  Knowing the strength of each, can help you to
greatly shortcut the time and effort it takes to get to a self-sustaining
99% native plant cover.

DOMINIC: >>   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.

REPLY: If I had not gone out a few months ago, and measured the 100-pace
transects with my own feet and notebooks, I would not have believed it
myself.  Mark’s 14 acres is 99.5% weed free.  Two Board members of the
California Native Grass Association went for a visit last month--Mark is
writing an article about his property for their journal, GRASSLANDS, and
may be published in the next issue.  I heard that the comment of one of
the Board members, was >> you could pull all the weeds on Mark’s 14 acres,
and carry them away in one pocket.

DOMINIC: 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.

REPLY: These two projects were not done with government grants by students
from a university, so there was no experimental design, or data
collection, or replications.  They were done by the land owners, each just
followed their successes, until they got it right.  Shaw has a crew to
manage his 74 acres, but Mark’s 14 acres is solely a family project with
no outside labor inputs.

These projects were done by the land owners themselves, who loved their
land so much, that once they got started on the path of weed management,
they were filled with a strong desire to see if they could get back to
100% native plant cover to permanently finish the job.  Shaw’s purpose was
that he had six foot tall Italian thistle so thick, he had to wear plastic
rain pants to walk through the property and not get his legs cut to
shreads.  Marks’ purpose was to clear out the broom (Cytisus) thicket so
he could build a home.

People from outside of California may not know, if you manage one weed in
our State without replacing it with a local native plant, you just leave a
vacancy for one of the other 1,000+ weeds to come and grow in that spot. 
The only permanent way to weed in California, is to do a complete
conversion back to as close to 100% native under story that you can get.

Mark is an engineer and Shaw is a land developer, neither with any
training in botany, ecology, or weed management, and both have been able
to do better in converting 99% weed-infested properties anywhere in North
America, and bringing them back as close to 100% native as anyone has been
able to achieve so far, as far as I know.

DOMINIC:.. 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!

REPLY: Actually TWO undescribed native species popped up on Shaw’s  land
when he got rid of all the weeds, that you can see at
http://www.ecoseeds.com/shawlist.html.  The undescribed Gnaphalium is very
beautiful in the morning, because the fine hairs on the leaves form the
dew into little pearls balanced on the surface of the leaf, and the new
member of the carrot family, is the Sanicula species nova.

Getting those two undescribed native species to show up is very
remarkable, considering how well botanized California is, but to me what
is even more remarkable is those dozens of other dormant native seeds that
were in the soil, just waiting for us to get the weeds off of them.

DOMINIC:.. 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.

REPLY: The measurement of the different allelopathic effects of each plant
is not arbitrary, and can give you very accurate dosages of what natives,
and in what amounts are needed in the ecosystem, to counter the effects of
the exotics.

DOMINIC:.. Does a layer of Nasella straw inhibit weed germination and
growth?  Does a layer of bark mulch?

REPLY: Yes, depending on how thick your layer is, what species of Nassella
and what kind of bark, and what time of year you apply the weed
antibiotic.  There can be big differences in the effects of say Nassella
pulchra straw vs. Nassella lepida straw, for example.

DOMINIC:.. Packing peanuts?

REPLY: Unlikely because they are made out of pure starch, but give them a
try also.  I would only use the ones made out of starch, and forget the
stryofoam ones.

DOMINIC:.. 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).

REPLY: I agree completely with you about what you are saying.

What I am suggesting is that if you are trying to manage weeds in a
wildland situation or manage rare or threatened native habitats, you
absolutely must invent a method, to be able to measure these plant
interactions very accurately, so you can you work done quickly and
efficiently.  This invention could also be very useful for converting
thousands of miles of weedy roadsides, back to self-sustaining native
roadsides, like what the Iowa DOT has been doing for a long time now.

  When you realize that every higher land plant on the planet as it grows,
gives off allelochemicals, then it means that we should strive to invent
the method to measure those effect, so we can use those chemicals for
our projects.

 DOMINIC:.. 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.

REPLY: As far as I know, I am the only one who has been using native grass
straw in his projects, out of the three we are discussing.

DOMINIC:.. 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.

REPLY: Yes, when we have a serious economic incentive to invent the
methods to measure the plant allelopathic interactions, then it will be
common knowledge for all to utilize.  Until that economic incentive is
there, however, it is up to the individual to invent the method
themselves, or license the method from someone who has, just like a
computer program or a computer operating system.

Once you have the method invented, it is very easy to get the numbers for
each species, and that is the beauty of finding a way to measure the
effect of each plant.  It ends up being just like a recipe--you need to
add 60% of purple needlegrass and 10% of California poppies and 10% of
miners lettuce, etc. to end up with a 99% weed-free self-sustaining native
landscape, to counterbalance the weeds in the area.

Sincerely,  Craig Dremann  (650) 325-7333

>> -----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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