Rethinking Restoration Ecology

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Rethinking Restoration Ecology

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This post is part of an ongoing series discussing the foundations and theory of Terrapin’s Framework for an Ecological Built Environment (Phoebe). Phoebe is a suite of tools that use ecosystem-based assessment to evaluate and improve the built environment. Phoebe merges sustainable design with environmental planning, industrial ecology, and restoration ecology. Its aspiration is to reconcile ecosystem dynamics and contemporary environmental pressures with human-dominated environments. These articles explore the ways these fields interact within the context of the thought process and goals of Phoebe.

 

Perhaps the most natural feature of the world in which we find ourselves is its continual flux.”

Jackson & Hobbs

*Header and feature image copyright Lucas Lof/Unsplash

Prairie ecosystem. Copyright Tim Good/Flickr

Prairie ecosystem. Copyright Tim Good/Flickr.

In 1970’s Chicago, restorationists began to restore the tallgrass prairie that once covered a large portion of Illinois before the land was settled. As the prairie was farmed by settlers, the grazing animals and prairie fires that once kept the savannah landscape open became rarer. The prairie was taken over by invasive grasses, the native oak trees surrounded by buckthorns, box elders and Siberian elms. Two hundred years later, Steve Packard, who pioneered the restoration movement did so because he believed we had “almost lost one of the richest landscapes on the continent” (Packard, 1988). To the restorationists, this was a 10,000 year old ecosystem with incredibly rich species diversity – they describe these prairie ecosystems as diverse and fragile, like a coral reef or an alpine meadow. Ten years after extensive research, clear-cutting and burning and planting in suburban Chicago, the ecologists and volunteers were rewarded with a landscape covered in purple milkweed, silky wild rye, pink phlox, “hundreds of thousands of blooming rare and uncommon grasses”; some species that were now rare in the state.  And yet, this restoration project met loud opposition from residents who could not understand why these ecologists were cutting down healthy trees – that provided many ecosystem services – to restore a fragile ecosystem that, to them, seemed expensive and futile. “Why,” they asked, “couldn’t they leave the forest preserve to evolve on its own?” While there was scientific reasoning behind the restoration: the sites, left untended, would evolve into simpler habitats, with dwindling species richness and health, this was not clear to people living in the ecosystem. There was a conflict between residents wanting nature to “take its course” and ecologists working to preserve the species richness from the past (Kendall, 1996). How do ecologists and environmental designers reconcile these differences? Should we be curating species diversity? Is there a “correct” role for humans in the maintenance of ecosystems?

What Are We Restoring To?

Ecosystem restoration covers a multitude of aims – from replicating a historical or reference state, to tailored restoration for specific species, to restoration of a degraded landscape for productive purposes. In the past, restoration ecology has looked to ecological history to identify appropriate targets to restore an ecosystem to, often a natural state that is pre-development. Defining a “natural” state is challenging, especially given the extent to which human activity has affected global ecosystems – is a “natural” state referring to pre-European land tenure? Pre-human influence? (Hobbs and Norton, 1996; Dayton and Sala, 2001) The lack of “pristine” habitats, or habitats that have remained unaffected by human influence has shifted the focus of restoration ecology from historical to modern ecosystem reference states in the last few decades. This represents a huge shift in the way we think about ecosystems. There are very few landscapes that aren’t affected by human activity – one could argue that since we can only preserve “natural” pieces of land through protection and management, they are not entirely pristine either.

Another reason restoring to a historic state is no longer viable is that the successional processes that create ecosystems are unpredictable, resulting in the possibility that ecosystems can evolve into multiple states. Whether these changes are driven by natural factors or by human activity, environmental conditions and species are reaching a “no-analogue” state. This means a state, or combination of conditions, for example, of soil structure and composition, hydrology, and species composition, that cannot be repeated in history – making restoration of an ecosystem to a more “natural” state difficult to achieve.

Another significant change in the practice of restoration ecology is the movement away from restoring to static states or baseline targets. Instead, ecologists may set targets in the form of ranges, or cycles. Given the full range of biological and biogeochemical fluxes in the past, we understand what “natural” variations to expect in an ecosystem. Ranges, like temperature, water flow or nutrient levels in the soil, more accurately represent the natural variance of a system than static targets – a healthy ecosystem is never at a single temperature, a stream has peak and base flows. However, even these ranges change over time, as the ecosystem evolves. Additionally, as we have learned from paleoecologists, going far enough back in time will typically uncover a range of states so broad as to be useless. Rather than thinking of ecosystems as inherently cyclical, they should be thought of as cyclical along a trajectory, changing shape as they do, sometimes dramatically. It is the constantly changing nature of ecosystems that keeps them flexible and resilient, adapting to new conditions with fluidity.

A more modern form of restoration ecology looks to contemporary ecosystems as a reference point. Restoration projects may set their targets based on an existing system, but these targets will keep evolving as the control site evolves. The focus has shifted from the idea of a “natural” ecosystem to a “healthy ecosystem,” and the goals associated with restoring degraded sites have shifted accordingly as our aim is now to create resilient ecosystems.

The Process of Restoration

How do ecologists set these goals? How do they choose the indicators to measure their success in reaching these goals? Ecologists will tell you that the first rule of restoration is: everything is negotiable and everything is site-specific (Young, 2014). The process depends on our perception of what is natural or healthy, and therefore desirable for a resilient ecosystem. There are several guidelines and frameworks present to choose ecosystem indicators and attributes to measure ecosystem health, but eventually these choices come down to the project location, and the goals of the restoration team – which goals are important in determining ecosystem recovery.

Ecologists may choose an ecosystem or a “control” site that represents the image of health they wish to restore a degraded ecosystem to. Taking baseline measurements at the control site, they are able to set goals for a degraded ecosystem, and metrics to measure them. As both sites are living ecosystems with distinct ecological trajectories, the goals of a restoration project will constantly evolve over time – what ecologists aim for is two ecosystems that have converging, not diverging trajectories. A robust design plan for a restoration project will not have an endpoint, but a known trajectory that will evolve with the site to reflect ecological and societal objectives.Based on these goals, they will choose indicators to measure the progress of the ecological attributes or services that they have chosen to improve. A restoration project that wishes to restore the climate regulation provided by trees may measure the carbon uptake by vegetation, temperature reduction around forested areas, or rates of evapotranspiration. These ecological indicators should be easily measured, sensitive to human and natural stresses on the system, be integrative and ideally represent information about the structure, composition and function of an ecosystem (Dale & Beyeler, 2001). Ideally, a restoration project will create measurable improvements to the ecosystem that are self-sustaining in the long run, ensuring that the system is resilient.

The Psychology of Restoration

The shifting nature of our relationship with the natural world has much larger implications for restoration ecology. From restoring ecosystems to a natural state, we have moved to restoring them to health – a move that acknowledges the evolving state of ecosystems, but also the permanent affects of human activity in every sphere of the world. Our ideas of ecosystem health have also evolved – they now include human values and ecosystem services, and therefore what we want from them has changed as well. Acknowledging that these biases exist (whether they be a preference for aesthetically pleasing species in an urban garden, or a guilt associated with planting non-native species), is particularly important for urban restoration projects.

Our perception of our role within ecosystems has also shifted. We now see ourselves as preservers, restorers or as a species within the larger systems we are studying and living in. What the Chicago example of prairie restoration shows us is the disconnect between the residents’ idea of ecosystem health – a more “natural” and therefore preferable version – and the ecologists’ view of what is healthy. To Steve Packard and other ecologists working on the prairie, the savannah was a community “whose continued existence depends almost entirely on a program of active restoration” (Packard, 1988). All that remained of the prairie were small clearings in between thickets of brush and invasive trees. The oaks that once were so integral to the savannah had been replaced by maples, ash, elm and cottonwood trees that the ecologists removed to open up the land, allow sunlight back in, and allow the oaks to thrive. In their mind “the prairie and the natural woodland were lonely for each other, incomplete and unhealthy” (Packard, 1988). There is a disconnect between the way people view their role in nature (“let nature take its course” said most of the residents) and the ecologists assumed responsibility to fix what humans have put in motion hundreds of years ago. There is disconnection in value systems: ecologists are restoring for resilience and health, and residents are protecting the ecosystem services and the sentimental value of trees that are familiar to them. Where does this disconnect come from and how can we reconcile the many ways we view ourselves within the biosphere? Viewing ourselves through the lens of ecosystem engineers offers a new perspective for this problem. Furthermore, understanding both built and natural projects, communities, cities, landscapes, and restored natural systems as part of larger ecosystems (a viewpoint offered through Phoebe), is critical in evaluating the performance and lifecycle sustainability offered through our ecosystem engineering.

Are We Engineering Ecologically?

Beaver dam. Copyright Aleksey Gnilenkov/Flickr.

Beaver dam. Copyright Aleksey Gnilenkov/Flickr.

Critics of the Chicago prairie restoration movement, and of restoration ecology in general believe that the value of nature and natural landscapes lies in their autonomy, in their history of pristineness. Restoration ecology, to them, replaces the internal logic of an ecosystem with the intentionality and design of human activity and needs. Eric Katz, one of Steven Packard’s critics, writes that “after a human intervention into a system, the resulting system will always be different from a natural progression without human interference” (Katz, 2002). To him, humans are incapable of restoring nature for altruistic reasons, and human and natural logic should be kept apart. But is this the case? Are there alternative ways to consider the roles of humans in ecosystems? Ecosystem engineering is the creation or modification and maintenance of habitats by organisms, often by causing physical changes to biotic or abiotic materials, and changing the availability of resources.  The responsible organisms, called ecosystem engineers, may do this through their own physical structures or changing the state of the material in their ecosystem. Through their actions, they control the availability of other resources for other species: energy, materials, space and food (Jones et al. 1997).  Beavers are a classic example: they cut trees and create dams to alter a system’s hydrology, and create wetlands from riparian ecosystems. These ecosystems, well-known to humans, may exist for centuries after, with an altered nutrient flow and decomposition rate, ultimately changing the nature of the water, and the plants and animals that grow around it (Jones et al., 1994). Beavers have been found to increase species richness of herbaceous plants up to 33% in their altered habitats (Wright et al., 2002).  Another example is trees: while the production of leaves and branches is not an ecological engineering process, the changes that this production causes in the environment, and the changes it makes to the availability of resources is a kind of engineering. Trees may alter humidity, temperature, nutrient cycling and hydrology, and create habitats that many organisms are, in turn, dependent on (Jones et al., 1994).

Humans are now the primary cause for changes in ecosystems, due to our own engineering. Whether intentional or not, our actions change abiotic and biotic elements in the ecosphere and alter the access to resources for organisms around us. Like ecosystem engineers, we heat seas and create wetlands and dig up soil (Wright & Jones, 2006). Viewing humans as ecosystem engineers may lead us to new understandings about ecosystem management. The actions of the beaver may be net positive, but they also may harm the species living in the trees that beavers fell down, and reduce the availability of resources downstream (Jones et al. 1997). Functionally, their alterations are similar to humans’, but an engineered ecosystem isn’t considered “less” or “more” healthy as a result, just altered. Humans have the benefit of understanding the long history of their impact, and communicating the values they associate with a healthy ecosystem: from ecologists to the public.

Understanding our role in ecosystems, effectively communicating the values that we see in our ecosystems, and shifting the focus from conserving pristine landscapes to nurturing healthy, integrated systems can change restoration ecology into a hopeful exercise, rather than a guilt-stricken reparation. Our biases will always be present in the values we associate with the natural world. Acknowledging them and our role within the biosphere is an integral part of resilient restoration practices.

At the heart of this debate is the fact that the frameworks of restoration ecology have changed with our perception of what is “natural” and “valuable.”  Restoration ecology now comes with a set of ideas about how nature should look or behave that reflects human values. What we want from our ecosystems has changed: we value healthy ecosystems as much as pristine ones (and recognize that these are not the same), we may value the services an ecosystem provides over its “nativeness,” and most importantly we value resilient ecosystems. This brings us back to the Chicago dilemma: whose values, and what values are we prioritizing in our relationship with nature?

What needs to change with this shift is the way we communicate and reconcile our values associated with an ecosystem: sustainable, social, ecological and aesthetic. Environmental scientists and designers will need to understand the values and biases inherent in the landscapes they are trying to restore, to understand what they are restoring to, and why. Along with this is the need to understand our role in these landscapes, and it has evolved over the years; perhaps viewing human activity through the lens of ecosystem engineering will give us the additional perspective needed to make restoration ecology a science of hope and sustainability.  This is particularly important when we consider urban ecosystems and the ways we can balance and enhance ecosystem services and function in our managed landscapes. Ecological restoration of urban landscapes leads to questions like what we’re restoring to or what we are restoring “for.” How do our ideas of natural and healthy change as we move across urban gradients? What kinds of goals do we set that will address human and ecosystem needs for a resilient future?

 

References

Dale, V. H., & Beyeler, S. C. (2001). Challenges in the development and use of ecological indicators. Ecological Indicators, 1(1), 3–10. doi:10.1016/S1470-160X(01)00003-6

Dayton, P. K., & Sala, E. (2001). Natural history: the sense of wonder, creativity and progress in ecology. Scientia Marina, 65(S2), 199–206. doi:10.3989/scimar.2001.65s2199

Henderson, H. (1988). Prairie restoration. The Chicago Reader. Retrieved from http://www.chicagoreader.com/chicago/prairie-restoration/Content?oid=872196

Hobbs, R. J., & Norton, D. A. (1996). Towards a conceptual framework for restoration ecology. Restoration Ecology, 4(2), 93–110. doi:10.1111/j.1526-100X.1996.tb00112.x

Jackson, S. T., & Hobbs, R. J. (2009). Ecological restoration in the light of ecological history. Science (New York, N.Y.), 325(5940), 567–9. doi:10.1126/science.1172977

Jones, C. G., J. H. Lawton, and M. Shachak. 1994.Organisms as ecosystem engineers. Oikos 69:373–386.

Jones, C. G., Lawton, J. H., & Shachak, M. (1997). Positive and negative effects of organisms as phsyical ecosystem engineers. Ecology, 78(7), 1946–1957. Retrieved from http://www.jstor.org/stable/2265935

Katz, E. (2002). The big lie: Human restoration of nature. In A. Light & H. Rolston (Eds.), Environmental Ethics: An Anthology (pp. 390–397). Wiley-Blackwell. Retrieved from http://hettingern.people.cofc.edu/Nature_Technology_and_Society_Fall_2010/Katz_The_Big_Lie.pdf

Kendall, P. (1996, October 6). Trouble in prairieland. Chicago Tribune. Chicago. Retrieved from http://articles.chicagotribune.com/1996-10-06/news/9610060245_1_steve-packard-natural-world-restoration

Packard, S. (1988). Just a few oddball species: Restoration and the rediscovery of the tallgrass savanna. Restoration and Management Notes, 6(1). Retrieved from http://depts.washington.edu/ehuf503/readings473/Packard1988.pdf

Palmer, M. A. et al. (2005). Standards for ecologically successful river restoration. Journal of Applied Ecology, 42(2), 208–217. doi:10.1111/j.1365-2664.2005.01004.x

Young, Truman. (2014, June 19). Telephone interview.