Some thoughts on "restoration" versus "rehabilitation" of natural systems

E-an Zen   September 2004 revision of April, 2003 draft

"Restoration" as an abstract concept may sound good, but is it practicable or practical?  I maintain that even as a concept it is problematic because: To restore, we must know the target time to aim for.  This requires multifaceted knowledge about a place at some specific time past.  In addition to the physical state of the site, we need also to know the forces that operated on that place at that specific time, including their directions, magnitudes, and their interactions.  Otherwise, merely to restore a state of affairs that we think existed at a moment in time, and expect it to remain afterwards, would be like trying to restore a meandering river by cutting out a serpentine channel, expecting the river to stay within its confines for the foreseeable future (1).

(1) This is no idle metaphor.  A State agency I know of tried just that a few years ago: they wanted to restore a channelized stream to its former meandering state.  Using earth moving equipment, they carved out an elegant meander.  At first, the stream behaved well.  Then a flood hit the area after a modest nor'easter.  Guess what - the meander was a messy wreck!  Likewise, we have plenty of records of efforts to "restore" beaches along the mid- Atlantic States; they ignored the forces working on the shoreline, and they all failed.

If we accept the notion that modifying forces had existed at the former time of interest accompanying the state of affairs then existing, and that these forces can be determined, then we must accept the idea that the state of affairs was not stationary but transitory, so that at a slightly later time the state would have changed.  If that is so, then one could ask, why not simply try to restore the state of affairs and forces for that later time?

Another problem is that our goal of reconstructing the desirable past is necessarily based on some crude overall time span, whereas the actual states and forces almost certainly had changed within that span, but their then-prevailing states, magnitudes, and sequences may well be beyond our ability to resolve now.  Thus the alleged previous conditions, i.e., the state we strive for, most likely were diachronous, thus probably not realizable, nor, if realized, assured as a duplicate of what actually prevailed.

All this, of course, presumes that the state of affairs we are trying to restore is "good" and desirable (presumably because it is beneficial for the ecosystem) on the basis of our present understanding.  For otherwise why should we try to regain that state?

Perhaps this emphasis on "restoration" is a legacy of the human tendency to long for and imagine the existence of a happier former state of nature.  As far as I know most traditions have that yearning.  In the Christian tradition, thus, we have biblical story of the Garden of Eden: that is to say, we had, through the misdeeds of Adam and Eve (or of modern human), fallen from a paradise that we now wish to regain.  Indeed, how much of the drive for restoration is based on cultural tradition, and how much on our knowledge of nature (2)?

(2) See, for instance, an interesting discussion by Cronon, William (1995): The trouble with wilderness; or, getting back to the wrong nature: p. 69-90 in Cronon, William, ed., Uncommon Ground: New York, Norton.

If, on the other hand, we look at ecosystem management and manipulation (for that is what we are talking about, make no mistake) as something we need to and must do in order to salvage the natural world for a livable future, then to harken to a past, whose quality is not necessarily desirable, may not be the best strategy.  We should ask, instead, "what would be the best for the future of the natural system?"  To be sure, to do that we must know the past processes, their threshold magnitudes and their time scales; but, more important, we should minutely examine the feasible paths to follow in a forward-looking mode, rather than let ourselves be engrossed in what we think had occurred during some poorly defined past.

In other words, we should be looking at our desired strategy as one of rehabilitation, in the sense that we want to make the site once again viable and habitable (3).  This may seem to be a quibble in words, but it is not: to rehabilitate, we look forward, using the knowledge and information available (and subject to adaptive management), whereas to restore implies a backward perspective with a healthy dash of hope that the former state was good, stable, knowable, and regainable.  The focus on rehabilitation does not rule out restoration as a part of the tool kit, but it is no longer the guiding light for management.

(3) We need to worry what these words mean in practice.  I would suggest that, as a minimum, rehabilitation should lead either to a local ecosystem that is robust, productive for the local and migratory lifeforms, resilient, and in harmony with its neighbourhood; or to one that can perform certain services for the human society, thereby freeing other regions that possess more options for their bes use.

If we make this change in perspective, we will have the luxury of looking both forward and backward, like Janus; no longer blindfolded by some hazy wishfulness.

Of course, if we make this change, we will still have to make major decisions, not all based on complete or even reliable knowledge.  We must, to begin with, decide our priorities.What are to be the guiding principles of our steps?  For instance, is it going to be for -

*Maximizing ecosystem productivity, such as

     *Maximizing capture of solar energy;
     *Maximizing primary production by photosynthesis;
     *Maximizing production of biomass;

*Maximizing ecosystem resilience;
*Maximizing biodiversity;
*Maximizing future land use options;
*Minimizing present fiscal investment into the process;
*Maximizing current human pleasure;
*Miniming human interference in the ecosystem;
*Maximizing landscape flexibility?
*Other goals?

Or is it going to be some compromise among these selections?  It is obvious that we could choose to maximize simulation of a past state (i.e., to restore).

The choices will be adventures, not only economically and socially, but intellectually.  A given choice may or may not be internally consistent or mutually compatible with other related decisions, nor, once made and implemented, likely reversible.  Some choices may require differing degrees of preliminary engineering of the land; some may presume a longer term of social commitment or social stability than others.  Thus, establishing a good set of guiding rules for selection will be important.  Note these rules are political, social, economic and cultural judgments even though science, sensu lato, must be a significant component for decision making.  Decisions may be locally or globally based, depending not only on the size of the site in question, but also, I think, on the expected impact of that site to the rest of our world. How to obtain the political consensus for a given path will be another big value-laden hurdle, but one that has been visited in the past (e.g., the Wilderness Act of 1964), so I will not comment further.

The correct decision about both priority and strategy must be site specific, and thus must take into account the peculiarities of the place at the time when action is to be made.  What kind of land?  Where does the place fit into the ecosystem, which surely is both closed and open (e.g. animal migration)?  Where is the place within the watershed?  What sorts of past legacy and damage must be considered, and where does the place fit within the human-centric habitation network?

Here are some potential sample issues: is the place a toxic site?  A part of a desert?  Will it have major landslide problems in the final, rehabilitated state?  Is the place a former hill/mountain top now excavated (e.g., strip mine site)?  Is it formerly or potentially a wetland area?  Is it on a floodplain?  What is the hydrological system now and what will it be after rehabilitation?  Are exotic species acceptable in the scheme of things?

Finally, but very important in my view: the time scale.  I have already alluded to the problem of time scale for restoration.  The same bugaboo will be waiting for us in the rehabilitation mode.  For a given site, how long should we expect the rehabilitated state of affairs to last? Surely, not "forever": it is not part of the vocabulary of reality.  We need to decide, before we start, what is realistic.  Understanding the time scale of expectable natural changes and of the processes of rehabilitation is the key to ward off assured failure.

I think a rough rule of thumb might be this: the engineered, rehabilitated state should last several times as long as it would take to get us there, for otherwise the state would be a mere blip in time, probably not worth the bother (and perhaps even harmful if the uncompleted rehabilitation effort leaves us with a worse mess than what we had to begin with).  This rule probably is valid on all spatial scales: from a single wetland area to a sustainable state of world ecology and economy.

If we want to rehabilitate a site to some specified state of affairs according to the wisdom of our decision makers, then we must shape the natural forces that will prevail, so that these forces can modify and reinforce the quality of the site in a desirable direction in some, presumably ecosystem friendly, sense.  These moulding forces can be expected to be individually and collectively non-linear in their function, and the life expectancy of the rehabilitated state will be strongly affected by their nature and strengths.  Yet, we cannot assume that our efforts at physically shaping the site (both animate and inanimate) will automatically result in the establishment of the desirable forces.

Because nature is never static, this shaping of the prevailing forces must be part of our planning process right from the beginning - a tough challenge indeed!  I might add that this requirement also applies to restoration; so this daunting challenge cannot be used as an excuse for going back to a restoration-based effort.

Presumably these individual efforts will take time to accomplish, and the time scale for each component of the overall effort will be different. The implementation of a particular change in the absence of those others not yet in place will present us with a new, if transient, reality that will force us to work under a different set of conditions and forces than what we began with and what we hope to finish with.  How do we make sure that these incomplete sets of forces will not wreak havoc during that period, possibly also making the final desired state unattainable?  How do we synchronize the effects of the intrinsically diachronous processes?

Thus my final words of caution, in this blurb of ignorance, is this: beware of our ignorance dressed as knowledge!  Be constantly conscious of the possibility of large and unintended consequences of our action! Beware of hubris and conceit masquerading as wisdom!

Finito