Can a vacant lot be….a dangerous idea?
Yes, argued a paper last fall in the journal Trends in Ecology and Evolution, if you think of that lot as a place that can’t be restored to a natural state before people turned it weedy and parkable (as in, “can be parked on by cars” — not “can be turned into a park”).
The paper highlighted one of the biggest scientific fault lines in conservation: Can such “novel” and “hybrid” ecosystems like that lot — human-altered places that include about 36 percent of Earth’s ecosystems, everything from farms to aquaculture to the plant-colonized sides of ruined buildings — ever be restored back to their prehistoric states? If so, which ones — and at what cost?
The paper’s authors, led by Carolina Murcia of the University of Florida and the Orgainzation for Tropical Studies, said the evidence is clear: Any ecosystem can be restored, given enough resources.
They argued that the very concept of the irreversible, phase-shifted novel ecosystem is unsupported by evidence. And they went on to say that the idea of novel ecosystems is a step back for conservation — providing a “license to trash” or “get out of jail” card for companies or others who want to sidestep the hard but ultimately beneficial investments restoration and biodiversity protection require. (Dan Simberloff, a coauthor on the paper, and Murcia have amplified on their argument in a recent piece for Ensia.com.)
Science is always about the play of ideas. So we asked seven scientists — including Erle Ellis, Richard Hobbs and Michelle Marvier — for their 100-word responses to the TREE paper. The answers are as various as ecosystems, novel or otherwise. (Editor’s note: The following should not be taken as responses to the Simberloff et al. Ensia piece.)
‘The fuss over labeling takes time and energy practitioners lack.'
Conservation practitioners find it hard to shake the feeling that dallying with “novel ecosystems” equates to giving up. Murcia et al.’s cautionary tone is therefore reassuring, although their recurring emphasis on the lack of “proof” of ecological thresholds detracts from a critical point: the fuss over labeling an ecosystem “novel,” “hybrid” or “historic” takes time and energy practitioners lack. Our core challenges remain: clearly define objectives, assess progress and adjust course as needed. No matter what we call them, those objectives should reflect the dynamic nature of the systems we manage and the emerging stressors that threaten their resilience.
‘Novel ecosystem science and conservation aim to expand the view of what “natures” are worth conserving'
I found the paper less than useful, scientifically and for conservation. The novel ecosystem community already knows, as the authors assert, that detecting “explicit, irreversible ecological thresholds [that] allow distinctions between ‘novel ecosystems’ and ‘hybrid’ or ‘historic’ ones” may be impossible. We also don’t intend to present a “clear message as to what practitioners should do with a ‘novel ecosystem.’” Novel ecosystem science and conservation instead aim to expand the view of what “natures” are worth conserving — beyond a return to “pristine nature,” a hopeless impossibility (e.g., Marris et al 2013) — and to explore all options and reasons to do so.
‘Decisions about managing ecosystems are colored mostly in shades of grey'
Thirty-six years ago I arrived in the western United States to a region dominated by sagebrush ecosystems that today has been transformed to large landscapes of an invasive Asian grass. Whitebark pine forests where I had hunted forest grouse only a decade ago are now largely dead or dying. Climate change is implicated in both cases; successful restoration efforts have yet to materialize.
Murcia and colleagues make valid points about the value of traditional restoration. Their critique of novel ecosystems, however, is limited by an impractical, black and white view of ecosystems, thresholds, and restoration itself. Decisions about managing ecosystems, unfortunately, are colored mostly in shades of gray.
‘Restoration and conservation have always absorbed new insights, challenges and opportunities'
Recently I visited a bald cypress swamp in Louisiana — beautiful, but with a floating understory of non-native water hyacinth that we soon found sheltering a native juvenile salamander. I’ve also seen thriving wetlands in California’s Sacramento-San Joaquin Delta without a single native organism.
These are real-world hybrid and novel ecosystems — a world Murcia et al would prefer we ignore regarding restoration and conservation options (especially when deciding whether something can’t or shouldn’t be restored). They fear derailing restoration and conservation; but these young disciplines have always absorbed new insights, challenges and opportunities, becoming better equipped to manage and restore systems for today and the future. Isn’t that what we all want?
'I thought troublesome ideas were the point of science'
Murcia and colleagues contend that “[t]he ‘novel ecosystem’ label may provide a ‘license to trash’” and “scientists should exercise caution” when discussing such ideas. They cite ecosystems’ ability to recover from past disturbance as evidence that the novel ecosystem idea is misguided.
Ironically, I recently discussed the same studies regarding ecosystem recovery. In response, Miller, Soule and Terborgh cautioned that “blanket predictions about nature having a high level of resilience are premature and may promote ecological tinkering.”
Somehow it’s unsafe to say nature sometimes cannot recover and it’s unsafe to say nature often can recover.
When did scientists start worrying so much about the dangerous implications of ideas? I thought troublesome ideas were the point of science.
‘Conservation: Let’s just get on with it.'
The term ‘novel ecosystems’ is an attempt to create a fundamental distinction between old and new thinking or functioning. Instead, it is nonsense, creating unhelpful polarization. Conservation is about negating human impacts on ecosystems and species. Murcia et al. are correct: no threshold exists beyond which we cannot return to a historic state. Leave my office alone for 1,000 years, and a verdant tropical rainforest replaces it. All ecosystems are in flux, and their ‘stability’ depends on how closely we look. Similarly, some parts of Earth need new conservation, while others do nicely with the old style. Let’s just get on with it.
‘Returning to arbitrary reference points will require the dislocation or livelihood transformation of hundreds of millions of people'
Seeking to return to “the historical trajectory of ecosystems before human activity” (if we actually knew what that was) would require the dislocation or livelihood transformation of hundreds of millions of people in places like Bangladesh, Haiti or Latin America. If we care about people as much as other species, this line in Murcia et al — “all ecosystems should be considered candidates for restoration, regardless of the requisite resources” — should instead be about restoring socio-ecological systems for their ecosystem services. Novel ecosystems like urban wetlands and rain gardens will be critical to restoring such services as watershed infiltration capacity (Tellman et al).