Sheila Walsh is an ecosystem-services analyst on The Nature Conservancy’s Analysis Team in Central Science. (Interview by Bob Lalasz.)

First question: “Ecosystem services” versus “biodiversity” — false opposition?

SHEILA WALSH: Biodiversity underpins all ecosystem services, so they're not mutually exclusive. We have growing evidence that greater biodiversity leads to healthier ecosystems, which in turn produce greater flows of ecosystem services. But it's not clear that biodiversity actually leads to greater ecosystem-service value, and that's because the value of ecosystem services depends on who the beneficiaries are, what they care about, and the relative scarcity of those services or the availability of things that can substitute or replace them. So, if you prioritize conservation based on biodiversity instead of on the value of ecosystem services to people, you might get different outcomes.

Example, please.

WALSH: If you have salt marshes near population centers, they might end up getting a greater priority for conservation under an ecosystem-services framework, despite having low biodiversity. That's because the damage to property that the marshes might help avoid during a storm could be quite high, because they're right in front of people's homes. But salt marshes with high biodiversity that are in undeveloped areas may get low priority under this framework (unless, of course, these marshes provide other significant benefits in terms of aesthetics, carbon sequestration or recreation, for example).

There’s a recent analysis of TNC projects — those that have biodiversity goals and ones that have ecosystem- service goals. It found that the ones with ecosystem-service goals also support biodiversity goals by using traditional approaches, such as protected areas, but have the additional benefits of letting us work in new landscapes, engage new stakeholders and motivate new investors in conservation.

So why even prioritize biodiversity anymore over ecosystem services?

WALSH: There are important ecological and economic reasons as well as strategic reasons why both biodiversity and ecosystem services should be part of our approach to conservation. A biodiversity approach will probably always be an important strategy for achieving certain conservation goals and engaging stakeholders that care more about biodiversity than services.

You can also think about biodiversity approaches to conservation as essentially a precautionary approach for protecting ecosystem services. These approaches allow us to maintain the option to use ecosystem services in the future when currently we may not understand how they are linked to biodiversity.

But if we’re looking at a portfolio of targets, and there are a couple of salt marshes in there and we have to make choices, shouldn’t we always choose to protect the salt marsh that provides the most ecosystem services over the salt marsh that may contain the most biodiversity but might not have as much ecosystem-service value?

WALSH: That's a great question. I really think we can frame our objectives with regards to biodiversity and ecosystem services in a few different ways, allowing biodiversity, ecosystem services, or benefits to people to be the main or joint focus. But I don't think they're always going to be in conflict with one another for ecological reasons, because biodiversity underpins ecosystem services. Even when you're focusing on ecosystem service values, you may actually also be achieving biodiversity goals.

For biodiversity, we have a great set of well-established indicators. Is that the case for ecosystem services?

WALSH: You can think about habitats as the stocks or the natural capital from which ecosystem services flow, and then the value of those services is determined through this filter of economics or essentially what people care about, what their values are. TNC is of course really good at understanding habitats, and we also have a good sense of what ecosystem services probably come from those habitats, so it may be appropriate to use the heath of those habitats as indicators in some situations.

Science is definitely getting better at measuring actual flows of ecosystem services — the amount of clean water per unit time provided to some town, for example. We also have more and more science on calculating the value of the flows of those ecosystem services. The core science is definitely there. It's actually an issue of bringing together the science from the different disciplines and getting us to apply it more. I also think that sometimes less complicated indicators are going to be more appropriate for the task, and we don't always need to go all the way to valuation.

One of the big advantages of monetary valuation is that it’s really powerful for bringing the benefits of nature into decision-making processes that use dollars and would otherwise count the value of nature at zero. But the main point of valuation is to put ecosystem service values in a common metric so that we can make comparisons between different alternative scenarios. The value doesn't have to be expressed in dollars. It can just represent some weighting of the relative importance of the services, either based on expert judgment or people's opinions and their beliefs.

How does that work in real life?

WALSH: Say you’ve got a landscape where clean water is one service and carbon sequestration is another. Now you’ve got apples and oranges, and you may have a scenario where having more of one means you have less of the other. You could have a group of stakeholders use a voting system or other weighting system to essentially show how much they think carbon sequestration and how much clean water matters to them. And they don't use dollar signs.

You mentioned that we need to bring together the science and apply it more. Is there a drive at TNC to do that?

WALSH: We're engaged in state-of-the-art applications with the InVEST tool from the Natural Capital Project. InVEST is really grounded in very well-established ecology, hydrology, and other biophysical sciences and economics. Of course there is a lot to learn in any application of InVEST or any other method or tool. Where there's a lot of need for science going forward is in understanding not just how people affect nature, but how nature affects people and their decision-making. That is going to be really key in helping us to identify and design strategies to align economic incentives with conservation goals. That’s something we will be doing with the Dow collaboration.

What’s your role on that project?

WALSH: I am going to play a lead role in developing and applying ecosystemservice tools to help in Dow's decision-making process — essentially to help Dow recognize and incorporate the value of nature into their everyday business decisions.

For science, what’s going to look different about the Dow project than what TNC already does?

WALSH: Big picture, this project really draws on TNC's heritage of using innovative, pragmatic solutions to conservation. It really builds off of our successes with Development by Design, and we will be working to integrate ecosystem services into that framework. What’s probably going to be new — and where our science is going to make some big contributions — will be connecting work on evaluating habitats, measuring ecosystem services, doing valuation, and then inserting that information into business decision-making frameworks and considering feedbacks between the business and nature. The aim is to align economic incentives with conservation. It’s not completely new, because we have done that sort of work already with payments for ecosystem services.

So you left a post-doc at Brown to come here. What were you working on?

WALSH: How local institutions like fishing cooperatives can manage resources under different ecological and economic contexts. I'm really interested in how context influences the relationship between people and nature and how it can help us identify conservation solutions.

My dissertation was basically on linkages between coral reef health and human welfare, and two parts that are relevant to what I’m doing at TNC were prioritizing management of different threats at ecosystem scales, and evaluating conservation solutions.

Here’s an illustration of what I mean by context. During my dissertation research, I looked at an alternative income program and how it affected fishing, coral reef ecosystem services and human welfare. And I found that when you pay people more to do agriculture, they actually fished more, because they could earn the same amount of money in less time, and they used their extra time to go fishing because they enjoy fishing. So the lesson is that you can’t ignore the non-monetary benefits of livelihood. Not everybody is motivated by wages. It really kind of hit us, like the bumper stickers that say "A bad day fishing is better than a good day at work." That's kind of obvious all of a sudden, and yet has really big implications for conservation-development policy. It was really important to me to have both strong theoretical and quantitative skills and then to be able to just spend time in those places and understand how coral reefs work, how people's livelihoods depend on them, and then understand what people care about and what factors they are responding to.

Can that apply to Dow?

WALSH: Oh, yeah. You know, lots of economists would like to say, "Well, you know, we can model all that, too.” But sometimes you need to think like a regular person (or better yet: an anthropologist!) to recognize those things and realize they are important to your economic analysis. We need to all step back and think about how people relate to nature and how people are making decisions, even when nature isn't in their thought process.

So I expect that we are going to find some new and sustainable ways to protect nature through the Dow project, and part of that is going to be having nature's benefits take a central place in the minds of corporate managers. That might not be a measurable outcome, but it's going to probably be one of our most important ones.