Undeveloped areas in the far north
“Many natural processes take place over very long periods of time: the formation of ice sheets and permafrost regions or the shifting of forest boundaries,” says the biologist from the Potsdam Alfred Wegener Institute for Polar and Marine Research (AWI), who also serves as a Professor of Paleoecology and Paleoclimatology at the University of Potsdam. Over the past 200 years, the Arctic has warmed drastically, yet the tree line has barely moved. “Some changes only occur after hundreds of years. But even if they are inconspicuous, they have a significant impact on plants and animals.” As global warming progresses, for example, the tundra is retreating further and further north all over the world. The unique vegetation, composed of mosses, lichens, grasses, and hardy herbs, is being displaced by shrubs and trees, which will have a negative impact on plant diversity and ultimately also on the animals that live there. A look back at the last ice age shows just how far this can go: as the grasslands receded, the forests gained ground – uncomfortable for mammoths, which could no longer find food there and finally became extinct.
When Prof. Herzschuh sets off on research trips, this is usually not an easy endeavor. Her field laboratory may weigh 1.5 tons, which can often be transported only by helicopter. Although this is extremely time-consuming and costly, it is necessary because the scientist is mainly drawn to largely undeveloped areas far north – in Canada, Alaska, Iceland, and Siberia. On the one hand, this is due to the fact that many of the long-term processes in which Herzschuh is interested take place in the Arctic. On the other hand, the permafrost soils of Siberia and Canada are among the regions that are still largely unaffected by human activity. “There we still find near-natural systems that allow us to understand the fundamental relationships between climate and ecology as they would take place without us.”
Underground Climate Archives
A look into the natural climate archives usually leads downwards – into the ground, which consists of the deposits of past ages. A borehole just half a meter deep brings to light material up to a thousand years old. However, such time travel is hardly possible in Central Europe, as the landscapes are too heavily shaped by humans. Prof. Herzschuh and her team therefore regularly endure the hardships of long journeys to take samples at particularly suitable locations. And these are often found at the bottom of former lakes. “Lakes formed by glaciers often exhibit stable conditions over thousands of years. This makes it very easy to understand how the ecosystems in the surrounding area have developed.” In addition, the DNA of the flora and fauna that sinks to the bottom of a lake over time is particularly well preserved.
These sediments are Herzschuh’s specialty. At the AWI in Potsdam, she has set up her own laboratory for the extraction and analysis of ancient DNA. “There are only a few laboratories like this in Germany,” she says. “The difficulty is to extract the DNA cleanly – and to interpret it. Over the years, we have acquired the necessary expertise. We know how different sediments behave and how to interpret them.” Networking with colleagues at the University of Potsdam, such as the plant ecologist Prof. Florian Jeltsch and the evolutionary biologist Prof. Ralph Tiedemann, was also helpful.
Her comment on the fact that she was awarded the Leibniz Prize this year: “A prize like this is, of course, a recognition that feels good,” she says. “But in research, virtually no one is a lone fighter; we work in teams that deserve this award as well.” The award winners may invest the prize money of around 2.5 million euros in their research freely. For Herzschuh, this is a reason to dream of the next milestone: a laboratory that is able to extract old proteins from the drill cores. “While DNA represents a hodgepodge of possibilities, proteins are what has actually been realized of these. They can be used to determine which interactions took place between organisms – and from this, in turn, we can draw conclusions about climate fluctuations.” Research in this area is still in its infancy. But a new laboratory could give it a boost. After all, the future of our planet lies, at least in part, in its past.
By the way, Ulrike Herzschuh is not the only award winner in the family. The Herzschuhs’ passion for natural sciences apparently has a tradition. Her daughter Undine won the regional and state youth science competition “Jugend forscht” for chemistry at the beginning of 2024 and then finished fourth at the national level.
Ulrike Herzschuh is a jointly appointed professor at the Alfred Wegener Institute for Polar and Marine Research (AWI) and at the University of Potsdam.