[RWG] Ecosystem Restoration Collapse

[Wayne Tyson]

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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