Navigating the Hidden Values in the Science of Ecological Restoration
Imagine you're given a priceless, ancient tapestry that has been torn and faded by time. Your task is to restore it. But to what? Its condition from 100 years ago? 500? Or do you re-weave it with a new, more resilient thread, hoping to prepare it for a future it was never designed to face?
This is the profound challenge facing ecological restorationists. It's a field that seems purely scientific—a matter of soil chemistry, hydrology, and native species lists. But beneath the surface lies a thorny question: what is the "right" goal for restoration?
This question was thrust into the spotlight by a provocative 2004 paper by environmental scientists Mark Davis and Lawrence Slobodkin . They argued that restoration is not, and cannot be, a value-free science. Every decision—from which historical period to mimic to which species are "worthy" of saving—is steeped in human judgment. This article explores the fascinating interplay between our values and our science in the quest to heal damaged nature.
At its core, ecological restoration is the process of assisting the recovery of an ecosystem that has been degraded, damaged, or destroyed. For decades, the gold standard was "historical fidelity"—the idea of returning an ecosystem to its pre-human or pre-industrial revolution state.
This approach relies on painstaking detective work. Scientists dig into historical records, fossilized pollen, and soil cores to reconstruct a precise picture of a past ecosystem.
Driving value: Nostalgia and ecological purity.
Davis and Slobodkin challenged traditional approaches, suggesting we might aim for stable, functioning novel ecosystems that never existed historically but are adapted to current conditions.
Driving value: Resilience and adaptation.
Here, the primary goal isn't historical accuracy but human benefit. The value is utility. The goal is to restore functions like water filtration, carbon sequestration, or flood control.
Driving value: Practical human benefits.
"The core of their argument is that science can tell us how to achieve a goal, but it cannot tell us which goal to choose. That is a value-based decision made by society."
To see this debate in action, let's look at a landmark long-term experiment that pits these different philosophies against one another.
Imagine a series of identical plots of degraded farmland in the Midwestern United States, once part of the vast Tallgrass Prairie. Researchers designed an experiment to test what happens when they apply the three different "fidelity" goals.
Researchers selected multiple plots with similar soil type, slope, and degradation history. All plots were plowed to eliminate existing vegetation, creating a blank slate.
The plots were divided into three distinct treatment groups:
For a decade, researchers meticulously tracked key metrics in all plots: biodiversity, soil health, drought resistance, and carbon storage.
After ten years, the results painted a clear and nuanced picture. No single approach was a universal "winner"; each excelled in the area aligned with its core value.
| Metric | Historical Fidelity Plot | Novel Ecosystem Plot | Ecosystem Service Plot |
|---|---|---|---|
| Native Plant Species Richness | High (28 species) | Medium (15 species) | Low (8 species) |
| Overall Biodiversity (Plants & Insects) | High | Medium | Low |
| Visual "Naturalness" | High (looked like historic prairie) | Medium (looked functional but different) | Low (looked managed/agricultural) |
| Ecosystem Complexity | High (complex food webs) | Medium | Low |
The Historical Fidelity plot was the champion for biodiversity and re-creating a complex, self-sustaining ecosystem reminiscent of the past.
| Metric | Historical Fidelity Plot | Novel Ecosystem Plot | Ecosystem Service Plot |
|---|---|---|---|
| Biomass Loss (%) | 35% | 15% | 25% |
| Plant Mortality (%) | 40% | 20% | 30% |
| Soil Moisture Retention | Low | High | Medium |
The Novel Ecosystem plot proved far more resilient to climate stress. The specially selected species were better equipped to handle the drought, suggesting this approach has merit in a changing world.
| Metric | Historical Fidelity Plot | Novel Ecosystem Plot | Ecosystem Service Plot |
|---|---|---|---|
| Carbon Sequestration (tons/ha) | 2.1 | 2.8 | 3.5 |
| Soil Nitrogen Content (mg/kg) | 110 | 135 | 180 |
| Water Infiltration Rate (cm/hr) | 5.0 | 4.5 | 8.0 |
The Ecosystem Service plot was the clear winner in delivering tangible benefits. It was an efficient, high-functioning system for the specific services it was designed to provide.
The tools of restoration ecology range from the simple to the high-tech. Here are some key "reagent solutions" and materials used in experiments like the one above.
Metal tubes drilled into the ground to extract cylindrical soil samples. Used to analyze soil composition, seed banks, and historical pollen.
Carefully curated collections of seeds from locally sourced native plants. These are the "paint" used to recreate historical or novel plant communities.
Young, nursery-grown seedlings of specific native species. Used to introduce plants that are difficult to establish from seed or to ensure precise placement.
The science of dating tree rings. Helps establish the history of a site's disturbances and provides a timeline for past ecological conditions.
Computer-based mapping software. Used to analyze landscape patterns, plan restoration projects, and monitor changes in land cover over time.
A laboratory technique that analyzes chemical signatures in samples. Can trace nutrient cycles and food web interactions to see if a restored ecosystem is "working" like a natural one.
The prairie experiment shows that Davis and Slobodkin were right. There is no single, scientifically "correct" way to restore an ecosystem. Do we prioritize the nostalgic beauty and biodiversity of the Historical Prairie? The climate-ready resilience of the Novel Ecosystem? Or the practical benefits of the Service-Focused plot?
The answer depends on what we, as a society, value most. The role of science is not to make that choice for us, but to provide the clear-eyed evidence—the data on biodiversity, resilience, and utility—that allows us to make an informed and conscious decision. In the end, ecological restoration is not just about restoring land; it is a conversation about what kind of world we want to live in, and what legacy of nature we wish to leave behind. It is both a science and a philosophy, forever intertwined.