Can conservationists agree on land preservation strategy?

For years, ecologists have been at loggerheads about how exactly to decide what land should be preserved. Should the focus be on large contiguous tracts of land, or would it be better to focus on the most valuable, biodiverse plots of land, and save them, no matter the size? This disagreement has had real implications for landowners and conservationists and has led to fights about research, results and strategy. Matthew Betts, a professor in the Department of Forest Ecosystems & Society at Oregon State University, is the co-author of a new paper that lays out a strategy for finding agreement.

Note: The following transcript was created by a computer and edited by a volunteer

Dave Miller: This is Think Out Loud on OPB. I’m Dave Miller. We turn now to a contentious environmental debate you might not have thought about before. It boils down to a question: what’s better for ecosystems and biodiversity in this age of habitat loss and fragmentation, one larger reserve, or several smaller ones? It turns out ecologists disagree on the answer and the debate even has its own acronym, SLOSS, for Single Large Or Several Small. Matthew Betts is a professor in the Department of Forest Ecosystems & Society at Oregon State University. He’s part of a team that wrote a recent paper aimed at reconciling the two sides of the debate. They argue that without it, ecologists can’t provide clear advice to land managers and policymakers. Matthew Betts, welcome to Think Out Loud.

Matthew Betts: Thanks, Dave. Thanks for the invitation.

Miller: I’m thrilled that you’re on. Can you help us understand first the positions of the two sides at the heart of this debate?

Betts: Well, I’ll start by defining fragmentation. Fragmentation is literally the breaking apart of habitat on the landscape. And this is in many ways different to habitat loss. And we all know as conservation biologists that losing habitat is typically bad for species. But the debate has been around what the spatial configuration, or patchiness, of the remaining habitat is, and what role that plays in biodiversity. Over the years, some scientists have argued that it’s actually better to have the habitat more split apart into separate discrete patches. And others are arguing that really, we need to have large contiguous blocks of habitat that are well connected.

Miller: So for example, 50-acres are all in one postage stamp shape, as opposed to five squares that are each 10-acres, but that are separate?

Betts: Yeah, that’s well described. That’s exactly the debate. It’s not so much how much habitat, it’s the configuration or the way it’s laid out on the landscape. And the heart of the debate is that some would argue that having the smaller patches could be better, it enables conservation groups and policymakers to really be focused on the highest quality habitat. For example, representing lots of different ecosystem types by having patches distributed across the landscape. There are a number of other mechanisms, like prey species might be able to move among those patches better, but predators don’t, so it’s a way for prey to maintain their populations on a landscape.

And then on the side of having large contiguous blocks, we know that smaller patches tend to have higher rates of local extinction just due to random processes. If those patches are separated by inhospitable land, maybe agricultural field or pavement, species have trouble moving back and forth across those. That can result in things like inbreeding, genetic problems.

So it’s a long standing debate. It’s been going on 50 years. And the point of this paper really was to focus on what can these different scientific groups agree on, and then how can we move forward to provide recommendations to policymakers?

Miller: Unlike some political debates that are arguably more based on opinion, or less amenable to data, this one is at heart scientific. And I understand from your paper that it’s two sets of ecologists, broadly, each pointing to data to say “here is why this is a better recipe for biodiversity or healthy ecosystems.” How is it possible if they’re both pointing to data?

Betts: Yeah, that’s an excellent question. I think it cuts to the heart of many problems we have when it comes to public understanding of how science works in society. Debate is a fundamentally important part of the scientific process. It’s the way that we eventually converge on reality, on using scientific data to uncover truths. But there’s always this uncomfortable period where you have scientists using data to come to different conclusions. And it’s completely not uncommon in science. You can think about the masking element during the COVID pandemic.

Scientists over the years have been analyzing different data sets of different scales with different species in different parts of the world. And we think that some of these differences are what is at the heart of this debate about fragmentation.

Miller: In other words, these are all scientists who are working in good faith and designing experiments. But the way you design the experiment and the question you ask it, it does have a bearing on the answers you get?

Betts: Absolutely, it does. An example, somebody might do a study on forest birds in the US in the temperate zone-

Miller: That somebody has been you in the past, right?

Betts: It has. I have to come clean and admit that that may impact.

And somebody else might do a study on sloths in tropical forest. And birds in temperate zones might be less sensitive to fragmentation for reasons you can probably understand, they can fly around, they’re quite efficient at selecting their habitat. Whereas sloths in the tropics are much less efficient at moving around, and therefore might be more sensitive to fragmentation. So a lot of it depends on which species you’re choosing, how you’re defining biodiversity, what landscapes you’re in.

In general, we found that tropical forest species are more sensitive to fragmentation than species that live in the temperate zone, up north here or far down south. So a lot of it depends. And the idea is to get proponents of both sides of this debate together in the same room and see what they can agree on, and see if they can agree on some of these contingencies I’m describing.

Miller: How have your own studies with birds influenced the way that you think about this debate personally?

Betts: I’ve done a lot of work in forests, and as you know, forests don’t have the nice clean lines of separation between habitat and non-habitat that, say, patches of forest and agricultural area might be. Forests tend to be gradients, different sorts of forests, different ages. And so something I learned really early on was, if you’re going to look at fragmentation effectively, you really need to see it from the eyes of the species you’re examining. For one species a landscape could be highly fragmented, think of a spotted owl that’s mainly associated with old growth forest. Today, that landscape is really fragmented. But for another species that’s more generalist, you might think about a black cap chickadee, the landscape is really not that fragmented at all. So if I think if we’re gonna get to the bottom of solving this debate or coming to some kind of agreement, it’ll come from understanding that landscapes are really different depending on what species you’re looking at.

Miller: One of the issues that is baked into this debate is just how much “edge” there is, how much dividing line between some kind of preserved natural area - where I’m imagining has its own rules, that’s why we’re talking about some version of conservation or preservation - and then the area on the other side of that where there are roads and buildings and humans doing human things. And by definition, the more divided up, more fragmented a habitat is, the more edge there’s going to be. What effect does that have?

Betts: Boy, I feel like you’ve taken my landscape ecology class. These are really excellent questions. And this actually relates to my previous answer to your question, the effect of edge can very much depend on the species. Some species are strongly associated with edge, they’re actually attracted to it, because it’s this boundary between what could be two very useful habitats. Picture a bird of prey that’s foraging on voles in agricultural fields, but it likes to nest in trees. So edges are really beneficial to the species.

On the other hand, you have some species that are strongly negatively affected by edge. There’s a species, it’s an interesting one, called a brown headed cowbird. And it actually lays eggs in other birds nests, very cheeky, and then flies off and doesn’t raise its own young at all. It is very common at the edge. And so rates of cowbird parasitism are high toward the edge, and much lower as you move in toward the forest interior. So, any species that’s focused on by the brown headed cowbird is in trouble.

Miller: These are maybe the outliers among species that figured out ways to thrive close to humans. But I guess there are plenty of others that haven’t.

Betts: That’s right. And quite likely it’s going to be context dependent, depends where you are on the planet, how negative the effects of edge are. But many forest species do tend to be more negatively associated with edge than the human associated species.

Miller: What’s at stake in this debate? You’ve outlined some of the complications, and I’m sure we could talk for hours about the scientific intricacies, and to be honest, there were aspects of your paper that I, as a non ecologist, had trouble fully understanding in terms of the nitty gritty of the debate. But what are the repercussions of this long standing disagreement among ecologists?

Betts: Right. Some would argue that this debate is moot in some ways because we’re stuck with the landscapes we’ve got, can we really change the pattern of patches anyway? But my response to that is actually we have huge control over what our landscapes look like when it comes to their fragmentation. In forested landscapes, we can choose to conserve larger patches or we can have lots of residual small patches. Or we can choose to connect patches or not. And a lot of groups globally are really coming down pretty strongly on the side of fragmentation mattering, and they’re affecting their planning decisions based on that idea.

So for example, the Nature Conservancy has a North America wide connectivity plan, the idea being that you really need to have connected patches in order to facilitate species moving northwards. And proponents of the other side of the debate would say that’s crazy. Really, what you should be doing is focusing on the best possible patches rather than worrying about how the landscape is configured.

And the context for all of this is biodiversity is in precipitous decline. There hasn’t been a time of biodiversity decline like this since the last major extinction. And even the UN is saying there’s a biodiversity crisis, and extinction rates are between 100 and 1,000 times faster than the normal baseline rate. So if fragmentation is important, we really need to try and get this right. And as you probably know, there are some major national and international initiatives that focus on conserving natural areas. The Biden 30x30 plan is one, which is attempting to conserve 30% of US land in protected areas of some kind by the year 2030. So how do we do that? Do we conserve big blocks? Do we have small patches? Combination of the two? So resolving this debate is really important when it comes to biodiversity conservation.

Miller: But to rephrase the question that you asked just there, how likely is it that policymakers actually have the choice between conserving one larger parcel, or three smaller ones that equal more or less the same acreage?

Betts: I think it’s quite likely actually. When you’re talking 30% of the land area of the US, there’s quite a lot of latitude to engage in that sort of conservation planning. And this could involve compensating private landowners for conserving smaller parcels, for example, or choosing areas on federal land that are big contiguous areas.

And then also don’t forget there’s the opportunity for restoration. So if we want to do restoration, we might think about trying to restore large blocks that are connected versus many, many smaller patches that represent different ecosystems better. So I would say, and we see it in practice now, there’s quite a lot of latitude to think about these landscape configuration issues and policy.

Miller: What do you see as the repercussions of policymakers seeing this debate among ecologists? How do you think that that debate affects the decisions that policymakers might make?

Betts: You’ve hit on the main motivation for this paper really. And that’s that our concern was that policymakers and managers would see this debate and throw up their hands and really choose whichever side of it fit their needs at the time politically. And so in that way, as I said, debate is fundamental to science. But if it runs on a long time, it can start being detrimental. And so the hope here is that we can again come to some kind of agreement and that’ll help with policy making…

Miller: Let’s dig deeper into your recommendations. One of them is to collaborate on designing tests or methodologies that can tease out the inconsistent results that folks have gotten in the past. So what’s an example of what that might look like, in a way that our general audience can understand?

Betts: Well, it shouldn’t be that challenging to think about. It might be more challenging to do. But the idea is to get both sides of this debate in a room or rooms, somewhere in Oregon, probably the H.J. Andrews Experimental Forest Headquarters. We’ll bring people in from across the country. And importantly, we’ll bring in policymakers, managers, Indigenous groups as well, and really lay out what it would take. What are the fundamental tests that it would take that people would agree on if the outcome was in a certain direction, we would all agree that fragmentation matters or doesn’t matter? And importantly, under what circumstances, fragmentation matters or not. So I’m expecting this will be a couple of weeks long, and will involve data analysts and data sets and a wide diversity of viewpoints. It’s quite well known that the more diversity of viewpoints you have in a room, the more likely it is you’re going to come to a robust scientific finding. So that’s our hope with this.

Miller: I was taken aback by one of your lines in this recommendation section, near the end of the paper. You wrote “it will be important to start with the acknowledgment that our colleagues are competent and acting in good faith.” Why was it necessary to write that?

Betts: Well, I think that serves as the basis really for any conversation among people. There is an aspect of scientific publishing, we’re judged on the basis of how productive we are as scientists. And one concern is that the people are so focused on publishing that they care less about what the actual uptake of the work will be in policy. And so we thought it was important to put that down just so that when we’re all in the room, we have consensus on the fact that what we find is gonna be of critical importance to policymakers, and that any conflict of interest should be set by the wayside.

Miller: When I read that, I couldn’t help but think that you put that because you get the sense that within this particular scientific community, where I imagine everybody knows everybody, that it is not a given that people think that their colleagues are competent or assume that their colleagues are acting in good faith. Did I misread that?

Betts: I think there’s something to that, Dave. I would say this is more a case of the past than the current. But during the most heavy debates in ecology, and I would say even human health, the debate has raged so heavily that people have become enemies. At conferences, they won’t talk to each other, and it can be quite acrimonious. So this was just a way of saying “let’s leave any personality conflicts at the door and really focus on the science at hand.”

Miller: Essentially, this paper is a paper for your colleagues, for the community first, and then if all goes well, it could ripple outward from there. But what have you heard, if anything, from prominent leaders on the different sides of this debate?

Betts: Actually, two of the prominent leaders on each side of this debate are authors on the paper. And so we took this to be a real note of optimism, the fact that we had people from both sides signing on to this paper and saying “yes, it’s time to move forward and come up with some reasonable conclusions that policymakers can use.” So I am optimistic about the steps forward.

Miller: Has working on this project, which is focused specifically on conflict resolution in the realm of ecology, affected the way you think about other conflicts?

Betts: This paper in particular hasn’t, but I’ve always been a strong proponent of trying to use science and reason in decision making. And the hope is that some of the conversation around this will help people understand how science works, that debate can be very healthy in science. And ideally, we end up with some kind of recommendations that the policymakers will listen to. That’s the other potential gap, something called the implementation gap. Even if you had 99% of scientists agreeing on something, it’s no guarantee that those findings will be used in policy.

Miller: Climate change is a sad and perfect example of that.

Betts: You nailed it, it’s exactly the example. We’ve known about climate change effects for well over 40 years, even longer.

Miller: Matthew Betts, thanks very much.

Betts: Thanks for your interest, Dave. I really appreciate it.

Miller: Matt Betts is a professor in the Department of Forest Ecosystems & Society at Oregon State University.

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