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“We need a more complex picture of ecological processes.” – Why a paradigm shift towards an individual-based ecology is necessary

Illustration ökologischer Prozesse
Prof. Dr. Damaris Zurell und Prof. Dr. Florian Jeltsch im Interview.
Source : Andreas Töpfer
Photo : Tobias Hopfgarten
Prof. Dr. Damaris Zurell und Prof. Dr. Florian Jeltsch im Interview.

The world is in crisis. But not only climate change is alarming researchers; the biodiversity crisis has also assumed threatening proportions. There are still an estimated ten million species of animals, plants, and fungi in the world. More than two million of them are in danger of extinction – although it is almost impossible to put a precise number on this. The majority of species have not yet been studied at all, and the complex ecological systems in which living creatures coexist are still poorly understood in many places. To change the latter, scholars doing ecology and biodiversity research in Potsdam want to initiate a paradigm shift – toward an individual-based ecology. Matthias Zimmermann spoke to macroecologist Prof. Dr. Damaris Zurell and conservation ecologist Prof. Dr. Florian Jeltsch about growing expertise, important networks, and the question what an eye for detail can contribute to the bigger picture.

In what ways is Potsdam’s ecology and biodiversity research unique?

Jeltsch: There are three main things: First, our specific focus on quantitative, process-oriented ecology. Several research groups at the Institute of Biochemistry and Biology have been working on a better understanding of complex ecological relationships for a long time. The consistent application of quantitative methods to the study of ecological mechanisms and processes especially distinguishes our work.

Zurell: In fact, quantitative research has steadily gained importance in Potsdam. In the process, ecological modeling has built up an excellent reputation over the past 20 years. I was able to observe this from a distance because I took my first steps as a researcher in Potsdam and came back to Potsdam in 2020. Over the past ten years, the quantitative component has also had a special twist – thanks to new and further developed sensor technologies such as GPS transmitters, camera systems and methods for the automated recording of biodiversity. The skillful linking of this experimental and empirical research with mathematical and computer-based process modeling has become a trademark.

Jeltsch: This combination, our second strength, allows us to generalize detailed empirical and experimental results and thus apply them to diverse (environmental) conditions and larger scales. For example, the Ecology and Ecosystem Modeling group is primarily researching the dynamics in aquatic communities and complex food webs. Led by Ursula Gaedke, the team of the DFG Priority Program “DynaTrait” investigates plankton and biofilms as empirical model systems in which numerous predator and prey species can mutually adapt. The combination of laboratory experiments and field data from Lake Constance with mathematical models allows the team to abstract the research results in order to derive general rules of interaction in ecosystems. Anja Linstädter’s group investigates how biodiversity is affected by land-use change, climate change, and other human impacts, especially in agricultural landscapes. Here, too, quantifying, process-based studies – in this case of plant traits – form a focal point.
A research focus of my own group is the movement of organisms – a key mechanism that influences biodiversity through the distribution of genes, resources, individuals, and species in space and time. To do this, we use state-of-the-art sensory technologies such as GPS telemetry with internal accelerometers, which we combine with advanced statistical analyses and spatially explicit, individual-based modeling. This allows us to investigate the causes and consequences of changing movement patterns in dynamic, anthropogenic landscapes for wildlife populations and biodiversity dynamics, e.g. in the context of our graduate program “BioMove”. Quantifying processes also plays a central role in Jana Eccard’s and Damaris Zurell’s groups.

And thirdly, Potsdam has a uniquely dense and diverse research landscape in biodiversity research ...

Zurell: This strong networking of Potsdam’s research is also reflected in the diversity of the investigated systems. For example, we do not only look at diverse ecosystems individually, but link our findings with each other, for example from aquatic and terrestrial studies. Our research deals with cities as economic-social-ecological units as well as with changing agricultural landscapes, drylands, and aquatic communities. Our research subjects include microorganisms, plants, and wildlife populations alike. This networking is strengthened through the cooperation with the many non-university research institutions in the region, which have found their institutional framework in the Berlin-Brandenburg Institute for Advanced Biodiversity Research (BBIB).

What makes Potsdam’s ecology and biodiversity research so successful?

Jeltsch: For a long time, ecological research focused, for the sake of simplicity, on populations consisting of identical individuals, i.e. based on mean values without considering individual differences and their distribution. This is no longer sufficient! Especially in light of challenges posed by global changes, we need a more accurate, partly more complex picture of ecological processes. Therefore, our research approach places individuals and their interactions at the center. We consider individual organisms as the smallest natural unit responding to environmental change. Only on this basis can we understand how changes scale up to the level of populations and species communities.

Zurell: Potsdam started establishing individual-based models as a strong theoretical tool early on. Ultimately, an entire population or community does not respond to environmental changes in the same way, but individuals respond, and the different responses of all individuals then result in the system response. Averaging approaches do not capture this well. By now, we are getting to the point where we can use individual-based approaches to develop predictive models and estimate future biodiversity trends.

To do that, we need to understand many complex processes: How far north will certain species spread as a result of climate change, how will biotic interactions change as a result, and are native species able to respond quickly enough? How does human land use constrain animals and plants, and how do they interact with the changing environment? These questions are met with intense public debate because the consequences of climate change have become visible and tangible to many people. With a view to the future development of biodiversity and appropriate management strategies, our research can make a difference.

Jeltsch: In the Research Training Group “BioMove”, for example, we study movement patterns of different species (e.g. bats, hares, wild boars, and various bird species) - and examine how they change as a result of land use, for example on agricultural land. These changes in movement patterns can in turn affect other species and ultimately have an impact at higher levels, such as the composition of species communities. Other projects, such as “DynaTrait,” focus on the level of evolutionary traits of individuals. We see shifts away from mean-based approaches in many projects. For example, in cooperation with Bayer CropScience, we studied the effects of herbicides on non-target plants and developed individual-based grassland models for this purpose. With their help, we can then scale up the described herbicide effects and interactions between individual plants to entire grassland systems. This methodological approach has made us successful in recent years.

What role do special methodological approaches play?

Zurell: Biodiversity and the processes that influence it are enormously complex. We need to look at species or species communities, how their environment is changing, how individuals of different species interact with each other, and who has what capacities to adapt. To do this, we need to refine our approaches and be able to apply them in different places to understand similarities and distinctive features of different ecosystems. We need to examine details to understand when the variability of single individuals plays a crucial role and needs to be incorporated into the models for the whole system.

Jeltsch: Our approach of an ecological paradigm shift towards an individual-based ecology requires better, individualized data collection. Measuring processes at the level of interacting individuals is enormously costly but possible. For example, there are new methods to record animal movement, behavior, and even physiology with the help of transmitters. These are in use in some of our projects. Other (e.g. acoustic) sensors are also becoming more and more sophisticated and the evaluation methods increasingly precise. Sensors are not only used to study animals, however, but also to observe plants and their interactions. This is a field that is developing rapidly. Newly developed experiments on individual behavior, such as those used in the Eccard working group, are another example.

Zurell: However, to be able to successfully apply the findings of single individuals to large scales and contexts, we need data from a large number of individuals on the one hand and expertise in processing them correctly on the other. Bringing together hundreds of thousands of individuals and abiotic factors requires big data expertise. There is still a lot of work ahead of us, but we are on a good path.

Jeltsch: Researching the evolutionary side of biodiversity is also becoming increasingly important. We have long been moving in parallel on different time scales, looking at both short-term adaptation and longer periods. Therefore, we are glad to have an evolutionary biologist on board with Ralph Tiedemann. This is also true for the current joint appointments of Christian Voigt from the Institute of Zoo and Wildlife Research (IZW) and Lynn Govaert from the Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), who both work at the interface of ecology and evolution. And, of course, we also rely on established, jointly appointed colleagues Hans-Peter Grossart from the IGB and Joerns Fickel from the IZW, who also conduct research at such important interfaces.

Zurell: One important question for ecological research is: On what scale do you conduct experiments? Because in addition to the temporal dimension, the spatial one also plays a central role for us. For example, plant species in landscapes sometimes influence each other on a small scale, sometimes over long distances. To measure these connections, we have developed and established the ScapeLabs under the umbrella of the Berlin-Brandenburg Institute for Advanced Biodiversity Research (BBIB). These are experimental platforms in which we can extend biodiversity research to the ecosystem and landscape level, that is, from the single individual to the regional level. With the AgroScapeLabs, the CityScapeLabs, and the LakeScapeLabs, we have such multi-purpose landscape laboratories for agricultural areas, urban spaces, and freshwater systems. This is unique in ecological research. In my macroecology working group, we go beyond that and use observational data from around the world to understand universal relationships and special features.

What role does networking with other disciplines at the university or other non-university institutions play?

Zurell: The importance of networking for biodiversity research is illustrated, for example, by one remarkable fact: In 2022, the Intergovernmental Panel on Climate Change (IPCC) issued its sixth Assessment Report, while the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) just issued its first report in 2019. Biodiversity is extremely complex, and we are still in the early stages of becoming a discipline that can make predictions. There are some ten million species and 200 or more ecosystems in the world that have already suffered significant damage from global change. To protect them from further damage or to improve their condition, we need multidisciplinary knowledge and methodologies. This includes various fields of ecology, evolutionary research and microbiology, as well as data science. Artificial intelligence, for example, can not only help with data acquisition and analysis, but can also be used in decision-making tools, e.g. to optimize management strategies.

Jeltsch: With the aforementioned Berlin-Brandenburg Institute for Advanced Biodiversity Research (BBIB), there has long been a platform of institutions conducting research on biodiversity in the region. The BBIB is our umbrella institution, a consortium of four universities and five non-university research institutions that helps us to bundle existing competencies in the fields of ecological, evolutionary, social, and political sciences in the greater Berlin area. Major projects such as “DynaTrait”, “BioMove” or “BIBS - Bridging in Biodiversity Science” show that this is successful. The latter, as the name suggests, has already successfully built bridges between different disciplines to improve our understanding of biodiversity. I think it is one of the particular strengths of our region that professional networking in various constellations has been established and is working well. The numerous institutions with their different focus areas are helpful in this respect. There are joint appointments with many of them. These include the Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research (AWI) with its focus on the Arctic and Antarctic, the Helmholtz Centre for Environmental Research (UFZ), where Volker Grimm conducts intensive research on ecological modeling, the Leibniz Institute of Agricultural Engineering and Bioeconomics (ATB) in Bornstedt and the Leibniz Centre for Agricultural Landscape Research (ZALF) in Müncheberg with their expertise on agricultural landscapes, the Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), the German Entomological Institute Senckenberg in Müncheberg and the Leibniz Institute for Zoo and Wildlife Research (IZW). Together with the Berlin universities and the University of Potsdam, the network is extremely well positioned.

Zurell: Modeling has become increasingly important in recent years for the synthesizing the bigger picture and bringing together the large amounts of experimental data. This is also reflected in our networks. As far as the integration of data science is concerned, we are fortunate to have very good colleagues at the University of Potsdam, such as Ralf Metzler from theoretical physics, whose methodological expertise helps us a lot.

Potsdam’s biodiversity research wants to submit an application for an excellence cluster in the next round of the excellence initiative. Why is Potsdam the right place for such an excellence cluster? And why now?

Jeltsch: With our many years of experience in individual-based ecology and in linking quantitative data with cross-scale modeling we are very well positioned for research into this field. In addition, our extensive network with its high density of research institutions guarantees a wide range of competencies and a broad spectrum of interdisciplinary topics. So, there is an enormous amount of experience and capacity here in terms of biodiversity research.

Zurell: Why now? Because it is urgent! The biodiversity crisis is here, and we need to invest as much as we can, as quickly as possible, to better understand biodiversity change, enable predictions, and initiate a better management of human impacts on ecosystems. The methods exist, but they must be brought together. That’s where we start – preferably with an excellence cluster.

How will you integrate and promote young researchers in the cluster?

Jeltsch: The “BioMove” Research Training Group, which has been working very successfully since 2016 and was extended in 2019, can serve as an excellent blueprint for us. It shows the innovative strength that young researchers bring with them. In this respect, I would say that such a group not only serves to teach young researchers, but that it brings an exchange with added value for both sides. And honestly, that starts at the bachelor’s and master’s level, where the engagement of the students is a tremendous asset to our research. They bring a creativity that you have to promote in every possible way. In that sense, it is up to us to create the necessary freedom and security so that young researchers are able to discover and create something. This is the basis for innovative research approaches, projects, and ideas.

Zurell: Such creativity is particularly important for us because biodiversity research is becoming more and more digital at an immense speed. Our individual-based agenda in particular is being enriched by new digital possibilities. Of course, it helps enormously that the younger generation of researchers and students are “digital natives” and can contribute impulses from a wide variety of fields. In this respect, there is once again the particular advantage of our location because we benefit from the quantitatively oriented training in our master’s degree in Ecology, Evolution and Conservation with the statistical methods of movement ecology and a focus on modeling.

Jeltsch: The Potsdam Graduate School (PoGS), which has been supporting doctoral students from all disciplines for many years and has played a major role in the success of “BioMove”, is also an important asset in the promotion of young researchers. We can build on this.

Zurell: The PoGS offers important individual programs related to research and teaching, but also beyond, such as mentoring or career counseling. And this doesn’t just start with the PhD phase. In fact, quite a number of our master’s students are already benefiting a lot from these programs.

How will the research results be communicated to the general public?

Jeltsch: Changes in biodiversity interest many people, even those who are not active in science. So our research will certainly be met with great interest! Fortunately, there are established showcases for this in Berlin and Brandenburg, such as the natural history museums in Berlin and Potsdam or the botanical gardens, with which we want to strengthen our cooperation. In addition, we are considering working with the Biosphere Potsdam to raise awareness for our topics among the public.

Zurell: Together with colleagues from digital education research, like Katharina Scheiter and Ulrike Lucke, we are also working on making not only our results but also the research itself tangible - for example with multimedia applications, apps, or games. In this way, we can, for example, bring ecological models that test what-if scenarios to life and visualize them. Digitization offers completely new opportunities not only for our research, but also for communicating it. We can show people how our environment is changing in the course of climate change. And we can bring concrete questions to life: What happens if we implement this or that measure? How can we support species? What does effective nature conservation look like? We have already gained initial experience with this at events such as the Potsdam Science Day - and we want to expand on this. In addition, our master’s degree program integrates the results of our research into the training of young academics in the most direct way possible, which means a very effective transfer of knowledge.

Jeltsch: Last but not least, our findings ideally also find their way into political decision-making processes. Policy advice based on scientific expertise is an increasingly important field, as the Corona pandemic has shown. Formats such as the UN Conference on Biological Diversity COP 15, held in Montreal in December 2022, are important platforms for this. An excellence cluster would offer the ideal starting position for this.

More information:

The Researchers

Prof. Dr. Florian Jeltsch studied physics and theoretical ecology in Marburg. Since 2000, he has been Professor for Plant Ecology and Conservation Biology at the University of Potsdam.
Email: florian.jeltschuni-potsdamde

Prof. Dr. Damaris Zurell studied geoecology at the University of Potsdam. After working in Zurich and Berlin, she became Professor of Ecology/Macroecology at the University of Potsdam in 2020.
Email: damaris.zurelluni-potsdamde


This text appears in the university magazine Portal Wissen - Zwei 2023 „Exzellenz (PDF).