Using Presettlement References

Knowing your restoration goals and correlating those to your resources is essential to success. Accept that your goals will change as you learn, too. At Driftless Prairies, we have an overarching goal of “increase biodiversity and decrease invasives.” Then each year, based on what the land tells us, we set our annual “to do” list.

As we discussed what our goals were, we had to look deeply into the notion that native systems needed restoring to presettlement conditions. Having spent time in historic preservation, the notion of something only having value if restored to original conditions, meant that something may not have longevity and be functional in today’s world. Which would make it obsolete.

I dug into this notion that restoring to presettlement conditions should be the ultimate and best goal.

Restoration practitioners and ecologists often use an ecosystem remnant as a reference site for what current goals should be and what future success will look like (Thorpe and Stanley 2011, Christensen et al. 1996). Certainly, the word “restoration” indicates we are returning something to its former self. But what the former self is? And is this feasible and responsible? “The original tallgrass prairie was so complex, variable, and diverse that an exact replica is not possible,” yet the recommendations have been to “emulate prairie remnants as nearly as possible” (Smith et al. 2010, Cairns 2000).

A remnant is a parcel of land that has remained unaltered and undisturbed by humans since presettlement times, which in Wisconsin is the 1830s. Yet, information on presettlement conditions is sparse, lacks complete and accurate accounts; it is primarily anecdotal (Hobbs 2007, Thorpe and Stanley 2011, Swetnam et al. 1999, Hobbs and Norton 1996, Landres et al. 1999, Wade et al., 2000, p.86, Clewell and Rieger 1997, Pickett and McDonnell 1989). Also rare are long-term empirical studies on community structure and composition (Pickett and McDonnell 1989). 

Additionally, in 1899 Henry Chandler Cowles’ wrote a series of ground-breaking papers illustrating that communities are dynamic and not static; it changed the field of ecology (Pickett and McDonnell 1989). Knowing this, I am astonished that conversations persist around using 1830s as the reference period for restoration. Aronson et al. (1993) coined the term “living museums” to describe goals on restoring to some pre-existing time. “Valuing the past when the past is not an accurate indicator for the future may fulfill a nostaliagic need but may ultimately be counterproductive in terms of achieving realistic and lasting restoration outcomes” (Harris et al. 2006). 

Our changing environment makes restoration to historical conditions unrealistic. “The pristine expression of nature at a specific site is a transient product of unlikely-to-be-repeated sequences of fluctuating weather, climate, and biological immigration” (Jones 2013). This sentiment is echoed by others. (Millar and Woolfenden 1999, Christensen et al. 1996).

Valuing the past when the past is not an accurate indicator for the future may fulfill a nostaliagic need but may ultimately be counterproductive in terms of achieving realistic and lasting restoration outcomes.

Professor James A. Harris

Establishing restoration goals and creating a management plan can seem overwhelming. Keep it simple. The following will guide you through the process.

Why the “presettlement” time period?

Early Euro-American settlers saw many desirable features in existing patterns of vegetation; these features were not static but represented only a point in time in the development of North American vegetation (Ryan 2000). Prior to the European invasion, the original landscapes were created, changed, and maintained by Native Americans. Often pre-Columbian human forces have been underestimated (Swetnam et al. 1999). In the northeastern part of the U.S., Europeans expanded agricultural processes begun by the Native Americans (Pyne 1982). Current pre-Euro-American settlement vegetation types may have little in common with present vegetation because a great deal of the original vegetation was logged and cleared for agriculture prior to WWI (Wade et al. 2000).

Like other aspects of history, one movement simply displaced and enlarged another.

1965 vegetation map of Wisconsin

Presettlement vegetation must also be considered in regional and sometimes microregional contexts. For southern Wisconsin, the presettlement period is the 1830s. Ignoring all other variables and focusing on a single element such as replicating the plants ignores the functional purpose of an intact, healthy ecosystem.

This is an interesting perspective on why we chose presettlement times as our guide. Pyne (2015) suggests that perhaps this insistent goal that vegetation look like presettlement days is part of our nationalistic attitude and in precedent-setting fashion, our national parks had a policy stating parks should be “recreated, as nearly as possible in the condition that prevailed when the area was first visited by the white man” (42). This attempt to override anything previous to the white man invasion overlooked nature’s complexities and the land’s history.

Surveyors were looked to as experts

Land survey records have provided the bulk of the early botanical knowledge yet they are fraught with imprecision. Not only were many were compiled after the 1900s (Thorpe and Stanley 2011), the surveyors were not trained botanists; they often worked in the winter; and they used common names (Cottam 1949, Kline 1979). In Wisconsin, public land surveys were not concerned with botanical or scientific findings; they were conducted for legal reasons and over a 34-year period (Schulte and Mladenoff 2001).

An example of a public land survey is to the right.

 

Example of Wisconsin public land survey

The importance of soil

Soil is key. It is responsible for controlling vegetation growth, especially prairie and savanna in Wisconsin (Leitner et al. 1991). The idea of remnant sod is intriguing, but soil science isn’t sophisticated enough to recreate the physical, chemical, biological properties of a past unknown soil type (Heneghan 2008).

We assume remnant communities have the same soil-forming processes and they function as they did in 1830. Yet, we’ve learned from testing 31 midwestern prairies that the soil characteristics and the microbial and taxonomic composition of 150-year-old prairies “vary considerably” (Fierer et al. 2013) from today’s prairies. Additionally we must consider the various man-made contaminants we apply liberally today; this alone means “the soil system cannot be quite the same as it was three centuries ago” (Hole and Neilsen 1970).

Variables other than soil and weather have changed our landscape since 1830, too. “Sustained heavy grazing along with weeds, promiscuous burning, and burning at unnatural times and intervals has resulted in species compositions and gene pools that little resemble the original presettlement formations” (Vogl 1974).

Restoring historical conditions is unrealistic

Nature is not static. Researchers emphasize the fallacy of creating restoration goals for a dynamic system based on a static point in time (Hobbs and Harris 2001, Aronson et al. 1993, Landres et al. 1999, Christensen et al. 1996, Hallett et al.  2013). Imagine choosing 9:01am on April 2, 1830 and replicating all the variables of that specific moment day after day. It’s not possible. We evolve. Ecosystems evolve.

While we understand that an ecosystem is a product of its past, it is also a product of its present and all the fluctuations in between. Focusing on a return to historical abiotic (physical) conditions assumes that once this environment is created or restored, the biotic (living organisms, food webs) will be able to resume their functions and stabilize the restoration (Heneghan 2008). From a historical perspective, this is not possible. Like the flora and the soils, the 1830s fauna was not well documented, and much remains unknown today. It is “naive to think we could restore a specified historical condition” (Hobbs and Norton 1996). Too little is known and too much has changed.

Land cover maps

Land cover maps in 1850, 1938, 1980, and 2002 across Wisconsin. The white areas represent urban areas and water bodies.
Source: USGS

Moving forward to present restoration work

Are we practicing what we preach? In 2013, a study was conducted of restoration projects in 54 countries; the researchers discovered many studies claimed to be using a historical reference yet in practice were targeting specific ecosystem characteristics (Hallett et al. 2013). Moving beyond the claims of that a presettlement reference is being used, look at the actions. Most agencies recommending seed mixes for plantings base them on what grows easiest and quickest. In fact, I would challenge you to find any group who recommends plants typically found in a remnant to be seeded into a planting. It could be they discount plantings, but with the continued destruction of what we call remnants, is it wise to disregard the recreation of critical habitat? 

Climate change must be considered

Climate change must be considered. If we are using purely historical references our restoration work could lead to failure in the next 100 years (Harris et al. 2006). Between then and now, weather, temperature, human-induced changes, extinctions, invasions, and land usage have changed ecosystem functions. When I began researching this, repeatedly, I would find statements like this one: Landscape changes preclude responsible mimicking of historical regimes because the climate was different then and will be different in years to come (New, 2014, p.167, Millar and Woolfenden 1999, Landres et al. 1999).

This essay provides some other aspects to consider.

 

Change — this is one thing we know with certainty.

Nature is ever changing; it’s dynamic. Our focus needs to be creating a self-sustaining, healthy, and resilient ecosystem that maintain biological diversity. How do we do this with out limited knowledge? We don’t which species are required to maintain key ecological processes and we have no method for measuring these processes?

I’ll leave you with this thought-provoking question…even if we could knew with 100% certainly the historical aspects of a piece of land, would it be prudent to restore it back to its former self or would it be more prudent to restore it so it is resilient and self-sustaining for the future? (Thorpe and Stanley 2011).

References

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Clewell, Andre and John P. Rieger. 1997. What practitioners need from restoration ecologists. Restoration Ecology 5(4): 350-354.

Cottam, Grant. 1949. The phytosociology of an oak woods in Southwestern Wisconsin. Ecology 30(3): 271-287.

Fierer, Noah, Joshua Ladau, Jose C. Clemente, Jonathan W. Leff, Sarah M. Owens, Katherine S. Pollard, Rob Knight, Jack A. Gilbert, Rebecca L. McCully. 2013. Reconstructing the microbial diversity and function of pre-agricultural tallgrass prairie soil in the United States. Science, v342: 621-624.

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