Simon Asher Levin

Simon Levin (Baltimore, Maryland, United States, 1941) holds a BA in Mathematics from the Johns Hopkins University and a PhD in the same subject from the University of Maryland (1964). He spent the next 25 years at Cornell University, where he was Chair of the Section of Ecology and Systematics and, latterly, head of the Center for Environmental Research and the Program on Theoretical and Computational Biology, as well as Charles A. Alexander Professor of Biological Sciences. In 1992 he joined the faculty at Princeton University where he is currently James S. McDonnell Distinguished University Professor in Ecology and Evolutionary Biology and Director of the Center for BioComplexity. Meantime, he continues at Cornell as an Adjunct Professor and is also a Distinguished Visiting Professor at Arizona State University. A Highly-Cited Researcher in 2021 and 2020 and honorary professor at Tsinghua University (Beijing, China), Levin is a former president of the Ecological Society of America and the Society for Mathematical Biology and a past chair of the Beijer International Institute of Ecological Economics. He serves on the advisory boards of ecological science related institutions in Austria, Brazil, Egypt, the United States, Israel, Italy, Japan and Sweden, and is editor of the authoritative reference book The Princeton Guide to Ecology and the Princeton Series in Theoretical and Computational Biology, among other publications.

Fahrig, Levin and Pickett have never worked together, but the three have made essential contributions, both theoretical and practical, in the field of spatial ecology. Levin has led its mathematical development, building it into models for the analysis of complex ecosystems. Fahrig studies the impacts on biodiversity of habitat fragmentation and loss of connectivity between remnant patches. Pickett is a pioneer of urban ecology, which assumes that cities will harbor a growing percentage of the population, making it vital to consider how urban spaces too can be used to conserve biodiversity.

The new laureates, the citation reads, have independently developed “the theory and mathematics of spatial ecology,” with wide-ranging applications that include “the design of nature reserves, and sustainable road networks and cities.” Their work “explicitly acknowledges the spatial dimensions and scales of organism interactions and the critical importance of habitat connectivity for the movement of organisms, materials and propagules [biological structures that give rise to new organisms] across complex landscapes.”

Understanding how physical space affects ecosystem dynamics and the life of organisms “is vital in ecology,” explains Pedro Jordano, committee secretary and a researcher at Doñana Biological Station (Spain). Landscapes and their management are important for migrations, for instance, and affect both species’ adaptive capacity and the size of the human footprint on ecosystems. Also, researchers need to be able to connect the results they obtain at a small scale, in manageable experimental systems, with what happens across wider regions or even at the global level.

Biodiversity is indispensable for the proper functioning of our planet: it produces oxygen, breaks down waste, and provides food, water and fertile land. Its global preservation is accordingly a challenge of the first order. One whose solution demands the knowledge embedded in contributions like those distinguished in the Conservation Biology category of the Frontiers of Knowledge Awards family.

Simon Levin made his own landmark contribution to the field when he unveiled his vision of spatial ecology in the paper “The Problem of Pattern and Scale in Ecology,” published in 1992, and still today one of the most cited in the ecological sciences. Until that point, Jordano relates, “ecology was lacking a doctrinal corpus that explained how to integrate different spatial scales, from local areas to continents. As researchers, we may start in small spaces, a pond for example, but we need to understand processes on a planetary scale.”

Mathematical tools to identify patterns across different scales

Levin, Professor in Ecology and Evolutionary Biology at Princeton University (United States), has equipped ecology with the mathematical tools to identify patterns recurring across different spatial scales.

“One of the greatest challenges facing our societies is the loss of biological diversity,” said Levin after hearing of the award. “Biological diversity is fundamental to us. In order to understand what is at risk, and to know what we can do about it, we have to understand the mechanisms that maintain biological diversity. That has been an essential theme in ecological theory for a century, but until recently there wasn’t much mathematical theory that incorporated the spatial dimensions of species interactions into models. So I set out in the 1970s to build models that incorporated spatial structure.”

For the secretary of the Frontiers committee, what Levin has done is to provide the missing theoretical framework and models “to understand how physical space influences ecosystem dynamics and the lives of organisms. His insights underpin studies that explain the processes of carbon fixation by forests, how animal and plant life are distributed across the landscape, the migration of animals or the dispersal of plants, how populations are structured and interact with each other, or how degradation processes in nature create impassable barriers and bring about situations of isolation.”

The importance of small areas and ecological corridors

Lenore Fahrig, Professor of Biology at Carleton University (Canada), refers to aerial views to illustrate how spatial ecology works: “We study how the distribution of the landscape, the different patches you can see from a plane, affects the life of organisms,” she said in an interview after hearing of the award. Fahrig is a pioneer in the study of landscape fragmentation and its impact on biodiversity.”

It is a topic that has immediate applications to very concrete problems: Is it better to create a really large protected area, or a lot of smaller ones? Is it useful to create “ecological corridors” between areas? And what impacts may derive from the layout of a given road?

“Habitat gets broken up into smaller patches due to human impact,” remarks the award committee, “and this is one of the most profound threats to biodiversity. Fahrig, it continues, “has developed theory-driven and data-proven ways for effectively reducing the effects of habitat loss by means of connectivity conservation. (…) Her work recognizes the critical role that road networks and small conservation areas play in altering the distribution and abundance of species.”

One of the conclusions of Fahrig’s work is that small patches have their value. As Jordano explains, “the developmentalist approach limited conservation to large areas, ignoring smaller ones.” What Fahrig has shown, he continues, is that “it is also important to conserve small areas, because if they are well interconnected, they can help preserve biodiversity. She has championed the idea of ensuring connectivity between reserves. For unless they are properly connected by natural corridors, the result can be a decline in species richness.”

“When I started my career,” Fahrig recalls, “the importance of ecological corridors was very far from clear.” Her research enabled her to document the huge biodiversity impact of roads, with animal roadkill at the top of the list, and has prompted a search for new strategies to mitigate the problem.

“The knowledge that we have about the harm we are causing is also the knowledge we need to stop the loss of species,” she insists. “It is entirely unjustifiable to be endangering a species for short-term economic gain. We know how to reduce our impact, and how we bring ourselves to do that is a matter of being aware of the value of nature and of other species.”

Designing cities for the coexistence of nature and people

Pickett, a researcher at the Cary Institute of Ecosystem Studies (United States), is described by the committee as a leading figure in the development of urban ecology: “He has been a pioneer in the important work of integrating humans as components of ecosystems into ecological theory,” the citation affirms, “linking ecology and urban design, and bringing ethical and philosophical perspectives into the study of human-dominated ecosystems.”

His work has been carried out in close collaboration with specialists in “architecture, urbanism, art, sociology, economics, and so forth,” Pedro Jordano points out. “The question is how we as people can get closer to nature, even in an urban habitat. And this is especially important in areas where the urban environment is close to nature in a wild state, as we have seen, for instance, in the case of pandemics caused by pathogens that have spilled over from natural reservoirs to human populations.”

As Pickett himself said after hearing of the award, “I think about cities as ‘patchworks’ composed of layers of many kinds. So there are the ‘built’ environments, the buildings, there are the roads, there is the infrastructure… But there is also a ‘landscape’ or patchwork of policy and regulations and norms. And then of course there’s a layer that deals with peoples’ social difference – differences in class and ethnicity and so on. And finally there is the green layer, the ecological parts of cities; what’s going on in terms of nutrient cycling and regulation of climate and flows of water. I try to deal with urban planning from all those perspectives, pulling them together.”

Among the first steps, he says, is to get our planning priorities right: “If you look at cities around the world you see that they are really designed for cars, and I think we need to flip that around and think about cities as being not only places that have to move materials and people around efficiently, but also places in which biology has to function, biodiversity has to prosper and perform functions that are useful for climate control, water control and even for people’s physical and mental health. We should design cities first for people and nature together, and bump physical efficiency and dimensions like transport further down the list.”

The importance of relaying science’s message to society

With the global biodiversity crisis looming every larger, Professor Levin believes that “it is not too late for us to take the necessary steps, but we don’t have a lot of time to lose.” The key, he is convinced, is “to get the message across to the business sector and political leaders, and the only way to do that is to relay the message to every citizen so they make their wishes known through decision makers.”

“We scientists,” he adds, “have a special responsibility, not only to do the work but to take the message to the public, and I’m hoping that initiatives like the BBVA Foundation Awards will begin to make people realize that we cannot just sit back and hope others will solve the problem for us. We have to address these problems ourselves, and we have to understand that in order to do that, we are going to need to find ways to cooperate across political and international boundaries.”