The first thing you might notice about the UNC River Ecosystems Group is the number of different disciplines represented: botany, land-use changes, chemistry, geomorphology, fluid mechanics, ecology, biology..."And that's by design," says Martin Doyle, Assistant Professor at the University of North Carolina and leader of the group. "They do bring their differing specific expertise, which is great, but I'm actually more interested in the fact that they each bring a completely different foundation from which to go after a problem, and that, for me, is the most exciting part of interdisciplinary research. It's almost more interesting to ask an ecologist to answer a geomorphological question than to ask a geomorphologist, because they're just going to have a completely different way of thinking about it."

The second thing you notice is that the group covers the gamut of habitat scales (see chart), and that their research, at each scale level, tends to cover both the biological and the physical sciences. At the micro-scale end, Daisy Small is studying the effects of turbulence on the movement of organic matter on stream beds. At the other, continent-scale extreme, Lauren Patterson is, among other things, looking at "the geospatial impact of extreme hydrologic events on human populations."

This eclectic mix can make life interesting in the weekly reading group, says Doyle, because "one week they’re having to learn about incredibly small-scale things and getting into differential equations and scaling numbers, and the next week we’re reading about how many people live in St. Louis."

For more on the group and what they're up to, visit the UNC River Ecosystems Group home page.

Overdoing Interdisciplinary?

But while Doyle is an obvious fan of cross-disciplinary research, he thinks too much merging of the disciplines is not necessarily a good thing. "A lot of people are saying that we need to develop these interdisciplinary degrees where students get degrees in river restoration, or they get degrees in environmental science." While Doyle thinks that there is a place for these programs, he is concerned that such an interdisciplinary melting pot might make graduates' approaches to stream restoration problems overly homogeneous, which means the ability to bring in outside thinking decreases. And he thinks that a diversity of approaches leads to better research and more innovation.

"When I was in consulting," says Doyle, "there was always a certain tension in a project where we had hydraulic engineers, geomorphologists, hydrologists, fisheries biologists, and botanists." This mix of backgrounds led to widely variable input into project designs, but with the character of the final product was usually driven by the training of the project manager. For example, says Doyle, "If the project manager had been an engineer, the project design would always have what they called 'the safety factor effect'. Yes, it was a river restoration project; yes, it had the input of biologists and botanists. But in the end, you could tell that the engineer’s fingerprint was on it because he would really be sure that it was going to be stable at certain discharges." On the other hand, if the project happened to have the fisheries biologist as the project manager, the end result might relax the safety margins in favor of more flexibility for habitat.

In the end, Doyle thinks that this variety in approaches is healthy for both developing the science as well as the practice of stream restoration.

New Trend: Mitigation Banking

When asked about current trends in the field, Doyle brings up the rapidly growing sub-field of mitigation banking. "I think we're sitting on a very big paradigm change," says Doyle. "What's been true is that if a river needed restoring, you had to go to a federal or state agency, who would issue a grant or contract for the work. What we're seeing now, especially in the Southeastern United States, is that increasingly rivers are being restored for mitigation purposes."

In mitigation, developers whose projects will end up harming the environment are required (by Federal and State laws) to offset this harm ("mitigating") by doing environmental restoration either on site or elsewhere, often at ratios of 2-to-1 or better (i.e. restore two miles of stream to offset the one mile that was degraded by the development project). The wetlands mitigation industry has been booming over the past decade, and what's new, says Doyle, "is that we're starting to get a booming industry in river restoration for mitigation purposes."

The "banking" part comes in as private companies realized that not only do developers not want to be in the restoration business themselves, they also don't want to delay projects until the offsetting mitigation work is sufficiently underway for them to get their permits. What private companies are doing is going out in advance and, say, restoring a stream. Then they get the appropriate state or federal agency to approve the results, which they can then "bank" as mitigation credits. Now when the developer is informed that to get their permit they'll have to perform some amount of mitigation, they can go to the mitigation bank and purchase the necessary credits. No need to learn the restoration business. No permitting delays.

Good News, Bad News

According to Doyle, there are several key benefits to this approach, and a couple of potential downfalls.

On the benefits side, the first is that to get the mitigation credits, the restoring company has to prove results, meaning they have to put in place the kind of post-project monitoring systems that are so often missing from traditional restoration projects.

Secondly, it is often more economical for mitigation banks to restore one large area rather than several small ones, so they have a tendency to restore geomorphic and ecological processes at larger scales. These larger scale restorations are what most ecologists agree provide the best restoration effect and benefits.

Third, they have a natural incentive to find and restore the easy areas first - this has an obvious downside, but it also means that many mitigation companies are conducting regional natural surveys for future site selection, and this can be helpful knowledge to have.

On the downside, the choice of mitigation projects is being driven largely by economics rather than science, and may not always fall under an overall regional ecosystems plan. This can be offset, however, by such plans being put in place by the permitting agency.

Secondly, the economic incentive is to design projects to yield the quickest credit-producing results. "It's not like when the Army Corps of Engineers goes in," says Doyle. "They are extremely cautious and methodical when they get into a restoration or dam removal project." However, there is a tradeoff: if the project fails, the mitigation company gets no credit and so no payoff. This provides a very real incentive to produce a successful project.

Finally, there are questions like how exactly to you assign credits, and for what? What about dams that should be removed but that have liability issues attached?

All this means, says Doyle, is that while there's a definite role for the mitigation banking approach to stream restoration, we shouldn't take the government agencies as well as research expertise out of the picture, because there are too many public interest reasons for restoration, and those projects may never see the light of day when the only light source is economics.