[APWG] Ecosystem restoration and alien species eradication Re:Performance standards to get weed-free and 100% native

Fri Aug 14 17:01:12 CDT 2009

APWG Forum and Patricia Ruta: 

I know that this might sound counter-intuitive, but continued disturbance of restoration sites, as in hand-pulling and other operations that disturb the soil, can have both positive and negative effects. There are many factors involved, and "context is everything," so each case has variations that prevent any one-solution-fits-all approach--that is, while sound PRINCIPLES are applicable to all cases, the ways those principles can be interpreted or misinterpreted and applied or misapplied are unlimited. 

This is not to say that hand-pulling or other means of suppressing or killing alien are in themselves "bad" or "good" practices, it is only to share the observation that the consequences of  "management" actions are not necessarily limited to the most readily observed ones. For example, pulling weeds can affect the development of indigenous organisms in negative and positive ways, such as killing emerging seedlings, disrupting the development of a mycorrhizal net, increase nutrient availability. This latter factor is sometimes interpreted as a positive, but it can be a negative factor with respect to the long-term development of a healthy ecosystem. (Dynamically) stable ecosystems are characterized by low available nutrient values, as the standing biomass sequesters available nutrients to a high degree, leaving the soil "deficient" in available nutrients. This low nutrient availability discourages weed growth, whereas high nutrient availability favors weed growth. Mycorrhizal fungi, free-living bacteria, and other organisms that characterize a stable ecosystem, are pathways and mechanisms that tend to render unavailable nutrients available to the native vegetation. This may be what makes some invasives able to invade "healthy" ecosystems--as when the invasive species is able to benefit from those soil organisms (e.g., obligately mycorrhizal) too, sometimes being able to both secure nutrients via such pathways and access available (such as those freed by uprooting or cultivating processes). In addition to a world of complex interactions at many levels that are within our knowledge-base, there are no doubt as many factors about which science remains ignorant--but it is that ignorance which drives science, right? 

At a practical level, there is the matter of "paradigm." Misconceptions can sometimes be generated by using gardening or farming paradigms (more available nutrients are good, irrigation is good, "management" is good, etc., when they are not applicable to ecosystems. It is sometimes very difficult for those of us (including myself) who were raised on those paradigms to "give them up." It took me at least fifteen years to figure out how different ecosystems and gardens are--a lot of "unlearning" had to be done. And there is the matter of rate of development, carrying capacity, etc., and how we perceive natural systems that don't play by out rules. We tend to be impatient, and we tend to want what we want, not necessarily what a given physical/biological context is capable of doing. 

WT

PS: A good book that goes into other key factors that affect the work of ecosystem restoration and alien species management is G. L. Stebbins' "The Genetics of Colonizing Species." It is HEAVY but stimulating stuff for those seriously interested in getting into the subject in depth. An "oldie but goodie," as is a lot of Stebbins' other work. Many other scientists in many fields have done volumes of research that can help us all make incremental improvements in how we see and do our work.

  ----- Original Message ----- 
  From: Patricia Ruta 
  To: Wayne Tyson 
  Sent: Friday, August 14, 2009 7:31 AM
  Subject: Re: [APWG] Ecosystem restoration and alien species eradication Re:Performance standards to get weed-free and 100% native

  I have seen some smaller parcels we have worked on with very good results of native restoration, but at this point, with only 5 years into the process of restoration, attention must still be given every year to treating NNIS in the restored sites (for the most part - hand pulling). Granted, after the first 2 years of intense weed management and now seeing very good stands of natives, the weed abundance is fairly light. 

  It seems well worth the effort to do the weed management- the public has even noticed and commented on their surprise at the low number of weeds. But, at this point, with the aggressive tendencies of NNIS, I can't see when we'll be able to stop doing NNIS work at these sites. While these sites have filled in well with mature native warm season grasses (little and big bluestem) and many nectar perennials,   thes esites are fairly sandy, poor soils (typical of mid Michigan). There are small gaps of bare soil (a matrix) and it seems like it will forever be a haven for spotted knapweed, sweet covers, St. Johnswort, etc. to get a toehold and eventually flourish and dominate at some point in the future if we don't remove those new sources of infestation every year or two. 

  Just my reflections. I have enjoyed reading this discussion. 

  " Finish each day and be done with it. You have done what you could. Some blunders and absurdities have crept in. Forget them as soon as you can."                         Ralph Waldo Emerson

  Patricia Ruta McGhan, Botanist
  Manistee National Forest
  (231) 745-4631ext. 3102
  email: pruta at fs.fed.us

        "Wayne Tyson" <landrest at cox.net> 
        Sent by: apwg-bounces at lists.plantconservation.org 
        08/14/2009 08:21 AM 
       To <apwg at lists.plantconservation.org>  
              cc  
              Subject [APWG] Ecosystem restoration and alien species eradication Re:        Performance standards to get weed-free and 100% native 

  Craig and all:

  It appears that other subscribers aren't interested in this topic, but I 
  think we should continue it anyway, in the hopes that a few will get 
  interested, or that it will stimulate "lurkers" to think about it. While I'm 
  greatly looking forward to a possible visit to your project and discussing 
  the particulars with you in depth, I suggest that we owe it to the 
  subscribers of this list to iron out the issues that each of us has raised 
  one at a time. I'll be interested in your ideas about this and those of any 
  who care to join in.

  Let's again revisit the issue of the importance of well-coordinated 
  restoration with eradication programs. You and I agree on this, I believe, 
  but perhaps there are others on the list who think that restoration is 
  unnecessary or irrelevant.

  I hope that all who may not agree will post their ideas on this particular 
  subject and that the discussion sticks to this one subject before moving on 
  to digressions. I am very interested in where subscribers to this list stand 
  on this subject. The only way I know to interpret their silence is to 
  presume that they agree and see no need for discussion or that they don't 
  want to discuss it for other reasons.

  WT

  ----- Original Message ----- 
  From: "Craig Dremann - Redwood City Seed Company" <Craig at astreet.com>
  To: <apwg at lists.plantconservation.org>
  Sent: Wednesday, August 12, 2009 12:23 PM
  Subject: [APWG] Performance standards to get weed-free and 100% native

  Dear Wayne and All,

  I want to start my reply, to wax poetically about how nice walking through
  a restored, a weed-free North American native ecosystem can be.

  It is like visiting the Promised Land, a fairy tale land that people talk
  about at annual wildland weed meetings--what would an area look like, that
  they have been weeding for years or decades, if it was not only weed free,
  but was 100% covered with the original pre-Columbian native ecosystem
  understory?

  The Shaw property is like a flawless 74-acre diamond, currently set in an
  unending ocean of almost a 100% solid exotic understory of over 1,000
  species of weeds, going 250 miles to the North, 200 miles to the East and
  600 miles to the South, to the Mexican border.

  ===============

  Wayne wrote:
  Mowing before seed-set is a reasonably good practice in some contexts, it
  may not always be practical (e.g., 2:1 slopes, etc.).

  Reply:  99% of lower elevation California is gentle slopes to fairly flat,
  so the level to gently sloping wildlands should be converted first, while
  there are still viable native seeds in the soil seedbank.

  If the native seeds in the soil seed bank are already 35-100 years old, my
  big concern is we will not get started in this conversion back to 100%
  native cover process, in time to take advantage of the viable native seeds
  that are lying dormant underneath the exotics, before they lose their
  viability.

  The clock is ticking for these native seeds lying dormant in the soil
  seedbanks, waiting for us to pay attention to them within our and their
  lifetimes, otherwise their lives will be lost forever.

  ===============

  Wayne wrote:  Once a site has been dominated by weeds for a year or two,
  not to mention decades or centuries, there is a considerable buildup of
  dormant seeds in the soil's seed bank. Mowing can't get those, nor can it
  get all of the standing crop.

  Reply:  Mowing absolutely must to get the standing crop of weed seeds
  before they ripen, for that year, and contrary to popular belief, you do
  not have to be concerned about the dormant weed seeds in the soil.

  What has been happening over the last decades or hundred years, is that
  the percentage cover of the weeds tipped the balance, where the weed
  densities were able to use allelopathic chemicals to suppress the
  germination of the dormant native seeds in the soil.

  See Journal of Chemical Ecology, especially Dr. Liu's 1994 and 1995 papers
  on a method to study plant-produced allelopathic chemicals  as an
  independent plant suppression system, separate from competition for water,
  nutrients, sunlight, etc..

  Where the concern should be focused, instead of the weed seed bank, is
  managing and resurrecting the native seeds in the soil seedbank, and once
  you cross a percentage native cover threshold, the natives will start
  permanently suppressing the weeds still viable in the soil.

  Those weed seeds will remain alive underneath the natives for a long, long
  time, but once you get the right densities or the right local natives in
  place, the natives will suppress the weed seeds from every germinating
  again, the weed seeds will eventually die in the soil.  Weeds Rest in
  Peace.

  =================

  Wayne wrote:

  Then there's the issue of the thatch/chaff, post-mowing regrowth, and
  other specifics that raise questions.

  Reply:  Thatch is not a problem. Fortunately most of the weeds that cover
  California are annuals, but for the perennials that might regrow,  is
  where a little brushing of the cut surfaces with Roundup might be
  necessary, like Pampas grass, Harding grass, etc.

  =================

  Wayne wrote:

  Not only that, but the vital importance that such treated sites must
  self-sustain rather than be continuously treated for eternity.

  Reply: That is why for the Performance Standards that I am recommending
  for restoration of California perennial native grassland habitats, on my
  web page at http://www.ecoseeds.com/standards.html is that you need to
  make the conversion from exotic cover, back to at least 95% native cover,
  within 90 days or less, with no future maintenance.

  If you have to weed after the 90th day, you need to do your small scale
  test plots over, until you get the right native cover that stops the weeds
  cold.  It is like a poker game, you have to lay down your Royal Flush of
  local natives, to beat the local weeds.  You do not want to have to keep
  playing hand after hand of weeding-poker to eternity.

  The only maintenance that might have to be done after the 90th day, is to
  add more local native species to increase the diversity, and to fill in
  gaps where native plant understory families have been catastrophically
  exterminated, like California and the West.

  Sincerely,  Craig Dremann (650) 325-7333

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