[APWG] Ecosystem Restoration Collapse
Wayne Tyson
landrest at cox.net
Mon Feb 27 19:50:18 CST 2012
APWG AND RWG:
For the sake of brevity and clarity, I'm going to annotate Harrison's remarks [[thus. WT]]
WT
----- Original Message -----
From: Ty Harrison
To: Wayne Tyson ; apwg at lists.plantconservation.org ; rwg at lists.plantconservation.org
Sent: Monday, February 27, 2012 4:04 PM
Subject: Re: [APWG] Ecosystem Restoration Collapse
Wayne et al.: I have been following these restoration/collapse discussion with great interest. I suspect many of us are, but have limited time to compose thoughtful contributions to the discussions.
[[While I fully understand the problem of time, any comments at all, from everyone, will contribute to a wider understanding and appreciation of this or any issue. WT]]
It is wonderful to hear from you professionals who have had much more experience in these dry, western grassland restoration projects.
[[Anyone can contribute insights and experiences; in fact professionals often miss points that a non-professional can see more clearly. There should be no hierarchy, no pecking-order here; we are all joined in a mutual effort to understand ecosystems and the role of weeds in them. WT]]
My experience has been on a much smaller scale, but I am bothered by many partial failures. One of the biggest issues has been to find a methodology to eliminate or control perennial grassy weeds as well as annual weeds which prevent the small, native seedling grasses to become established in sufficient density to eventually out compete the weeds after two or three years of mowing.
[["Partial failures" may not be failures at all. Our expectations of Nature and natural processes may be unrealistic. The important thing is the trend or direction in which a natural system is moving. WT]]
An additional frustration is that it has been almost impossible to get success in perennial native forb establishment with a native grass/forb mix on some of my semi-successful seeding projects.
[[While everything is context-driven at root (npi), there are a few generalizations that tend to apply to a number of contexts. For example, many indigenous species have a low survival rate (I can't remember the citation, but a doctoral dissertation by Robinson at Oklahoma State University, if I remember correctly, studied survivorship of Stipa pulchra in the 1960's or '70's that demonstrated and exceedingly low seedling survival rate when directly sowed in the field). I have found that planting "colonies" of small [1" x 3" container-grown seedlings in groups of about ten containers each to be quite successful, especially when combined with a small amount of inoculum from healthy stands to pencil out better in every respect [cost/effectiveness] than direct seeding. However, direct seeding with inoculum also can be effective in some situations. WT]]
I agree that to be successful you have to have the native grassland soil there, but many times that is not possible. I need to know what kinds of soil amendments or treatments need to be made to insure survival of the natives over the weeds.
[[Unless the basic requirements for the development of a grassland are present, one is not likely to achieve a grassland; some other plant community may be more suited to the site, and that fact should be faced. However, I have found that if the soil is fine-grained rather than coarse-grained, growing what I call "transitional" species can provide tons of humus and proper aerification, not to mention soil flora and fauna (e.g. fungi and earthworms) that would be prohibitive in cost and practicality to importing commercial "amendments" (unless the latter consist of topsoils). The roots of annual plants are notable for "amending" otherwise sterile and structureless dirt. When they die, such roots leave behind organic matter and root casts that increase water infiltration and percolation as well as available water capacity, just to name a few benefits, that commercial amendments cannot provide. Weeds and certain annual crop plants, especially those which rank low on persistence and reproduction, can accomplish this in a very short time. Planting the aforementioned colonies--just a few each year--will advance the project toward the ultimate goal and at the same time provide a demonstration of the degree of effectiveness and the trend, demonstrating the level of effectiveness at each stage of development. WT]]
My past experience, in contrast to Dreman's, is that highly fertile or fertilized soils simply allow the annual weeds to grow faster, shading out the slowing growing native seedling.
[[Exactly. One of the major differences between ecosystems and cultivated monocultures or plant assemblages is that ecosystems tend to sequester most or all of the available nutrients in their tissues, thus discouraging weed growth. Both fertilizer and water tend to favor weeds in most upland situations. Putting the ecosystem under what good agronomists and horticulturists would call "stress" fosters the development of the organisms best-adapted to it, while discouraging those ill-adapted to stress. You might say that in ecosystems, stress is the "name of the game." WT]]
Which indicates to me that first year mowing is critical for almost any annual weed infested grassland restoration.
[[Well, yes, mowing can open up the soil to light and heat, favoring the organisms that require those conditions, which can sometimes be the more slowly-developing perennial native species. Mowing is, however, a double-edged sword (pi), so one must use some caution. For example, one might not want to mow at certain times and one might want to rake up the hay. Seemingly tiny differences can be crucial in restoration. WT]]
I have seen one very successful native grass/forb seeding project on an Interstate Highway ROW, but it was destroyed by a highway maintenance reconstruction project.
In terms of "restoration collapse", of which I have seen many, weed re-colonization in any available open soil site, or small scale soil disturbances by rodents or fire, is the source of collapse due to lack of follow-up weed control.
[[It ain't necessarily so. A lot of the problem with collapse is due to failure to know what's actually going on. I am not a fan of "follow-up" work of any kind, especially so-called "weed control," because such activities, while viscerally and intuitively satisfying, often introduce more cons than pros. WT]]
Please keep these discussions going. I would like to learn more about assessment standards and techniques which are practical.
[[This is a big subject, perhaps deserving of its own thread. My own feeling about standards is that the initial presence of the right organisms is the first requirement, and most of the rest of it involves trend--up rather than down. Dr. Dremann and I disagree on some things, and without speaking for him, I understand that he believes "cover" is an important measure. I almost always believe that cover is not only misleading but counter-productive. I am well aware of the popularity of "cover" as a requirement that is quite popular with many agencies and that I am in the minority on this point. If there is sufficient interest, I will try to explain my reasoning and the observations that have led me to that conclusion. Unlike some, who have popped out of the womb of the university in an all-knowing and near-perfect state, I have made, and continue to make, more than my share of errors. For that reason, I am always happy to stand corrected on the merits or demerits of my statements and practices. WT]]
Regards, Ty Harrison, Emeritus Professor of Biology and consultant, Salt Lake City, Utah
----- Original Message -----
From: Wayne Tyson
To: apwg at lists.plantconservation.org ; rwg at lists.plantconservation.org
Sent: Saturday, February 25, 2012 8:33 PM
Subject: [APWG] Ecosystem Restoration Collapse
All:
One of my fellow subscribers has been corresponding with me off-list the subject of ecosystem restoration standards, and I have been unsuccessful in persuading the subscriber to keep the discussion on-list, as I believe the subject is of broad common interest. This person apparently believes that I am the only one (with one or two others) interested, because no one else has weighed in on the subject. Is this person right? Are none but three or four of us interested in this topic? Should this and related topics be kept off list (to keep topics of restricted interest from clogging the in-baskets of the majority? If so, how many subscribers are there to APWG and RWG?
I am hereby taking the liberty to broach the most recent topic, the collapse of ecosystem restoration projects, signified by the return of weed dominance in some cases. I would add to this that ecosystem restoration projects also "collapse" or fail to "take" whether or not weeds dominate. The off-list poster confined the comments to grasslands, so I will primarily address that issue, but the same principles hold true for other biomes and can be more broadly applied.
First, the "return" of grassland restoration projects to weed-dominance.
There are a number of reasons for this, some related to context issues like soil type, some related to restoration methods, but consideration of soil type must be part of the restoration assessment, planning, and execution process. Soil type is important; in the case of grassland restoration, it is preferable (actually essential) that a grassland soil is present--if it isn't, all the King of Restoration's horses and all the KoR's men and women will not be able to make a silk purse out of a sow's ear (without some major alterations to the soil). I invite others to expand and expound on this subject; I will mention only some factors.
True grassland soils tend to have identifiable characteristics. They tend to develop on alluvial or aeolian soils of finer texture and containing considerable natural humus and soil flora/fauna, as well as mineral deposits at depth (commonly at or near the effective bottom of the root zone) such as calcium and sodium. Disturbance of such soils can render the site largely incapable of supporting a true grassland, such as when bulldozed or otherwise excavated and the surface is changed from a grassland-type soil to a jumbled mass, sometimes consisting of coarse B-horizon or deeper deposits unsuited to grassland development. This should be determined in the initial assessment and feasibility investigation, and consideration should be given to restoring an ecosystem/plant community type other than grasslands, at least as a transitional measure until something resembling a grassland soil can be developed. (Wholesale replacement of the degraded soil with grassland soil can be done, but it is terribly expensive.)
If one tries to establish a grassland on non-grassland soils, one is most likely going to be disappointed, and "failure" is almost foreordained. I have, however, attempted to grow hair on such billiard-ball sites, with limited success. If other conditions are favorable, a soil can sometimes be developed (or its development accelerated) by certain tricks (e.g., praying for gopher or prairie-dog invasions, adding mycorrhizal fungi and other essential soil organisms, and transitional plantings of annual plants--sometimes even grasses, but more commonly dicots like weeds and flowers that will be humus-builders. Short-lived perennial plants, even some shrubs, also can be used. This approach is much cheaper than soil importation, and sometimes can be better. The actual strategy should fit the context.
I should make it clear that my first fifteen years of attempting ecosystem restoration projects were all failures by my own standards, and I have continued to make some mistakes once ever since. One must, I believe, learn from actual experience. However, just experience is no guarantee of expertise. If I had stubbornly held on to what I "knew" and refused to consider that what I knew might be wrong, I would have continued to fail. I did get to the point that could reliably initiate ecosystem processes and avoid "collapse." All restoration practitioners can do is to accelerate ecosystem development anyway, largely by setting up conditions that will permit or even maybe encourage natural ecosystems processes to work. We don't actually restore living systems.
In short, most failures can be traced back to the kind of work done and not done to set up favorable conditions for natural forces to work upon.
In short, two of my biggest mistakes (there have been many others) have been to:
a. fail to properly assess site conditions and develop a restoration program that modifies or matches those conditions.
b. plant too many seeds and plants, spending far too much money and doing far too much presumptuous guesswork.
If a grassland soil is present, indigenous species can persist and eventually re-assert dominance over weed populations. If one can mimic grassland soils, one has a chance of fostering the development of grassland, but one must out-draw the Lone Ranger to do it. If one is presumptuous enough to believe that all that needs to be done is to kill weeds and scatter seeds, collapse, unless one is terribly lucky, is rather more likely than not.
Disturbed sites (from bulldozing to trampling) tend to favor weeds. They are the scabs, as it were, on the scarred face of the earth--not pretty, but an inevitable result of land mismanagement.
2. Collapse of "restored" ecosystems that do not necessarily result in dominance of weeds.
This phenomenon is often the result of simply seeding or planting too many and/or the wrong balance of the right (and/or wrong) species at the wrong time, possibly including "maintenance."
This can be the subject of another discussion, but I have run out of time . . . (and since it does not include weeds so much, it might be "inappropriate" for these lists.
WT
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