With the effects of climate change, drought is becoming an increasing problem in many parts of the world. Michael Bahn, a researcher at the Institute of Ecology at the University of Innsbruck, has been involved in several studies on the effects of drought on ecosystems. These studies, recently published in leading scientific journals, provide insight into the complexity of the processes underlying ecosystem responses to drought. They emphasize the importance of biodiversity to enable natural systems to withstand drought.
The latest IPCC report makes it clear that as climate change progresses, extreme weather events are becoming more frequent and droughts are becoming more intense. Professor Bahn and his colleagues recently published several studies looking at different aspects of the impact of drought on ecosystems.
Look into the time machine
“To study how ecosystems are affected by drought, we installed rain shelters in meadows and forests. The aim is to understand how an entire ecosystem with its numerous interactions reacts to drought,” explains Bahn. “By heating sections of grassland with heaters and adding CO2 With their atmosphere, we can mimic the effects of a drought on a future world.” While warming increases both drought and heat stress, CO2 helps the plant conserve water by reducing water loss from the leaves. The Bahn’s multifactor experiments suggest that the impacts of drought will be more severe under future climate conditions, but that drought recovery will also be faster. “With this experimental approach, we can already predict future conditions today. It’s like a time machine,” says Bahn.
Such studies are invaluable for testing and improving ecosystem models. These allow scientists to predict changes in the environment of ecosystems and the impact of these changes on the climate. This feedback is mainly mediated by greenhouse gases, which include CO2 and nitrous oxide (N2O). “Our studies show that drought greatly reduces CO uptake2 through ecosystems. At the same time, precipitation after droughts often leads to increased emissions of greenhouse gases. Such “hot moments” are particularly critical for N2O emissions, especially from fertilized soil,” explains Bahn.
A synthesis study of many experimental and observational studies published in earlier this year Natural Ecology & Evolution showed that the productivity loss caused by drought can be up to 50 percent greater than assumed in experiments. Consequently, models and large-scale assessments should also take into account long-term field observations and large-scale analysis of satellite data. In another recent article in the same journal, the scientists suggest that as climate change progresses, the mechanisms at work in global drylands may play an increasing role in many of the currently wetter regions.
Resilience through diversity
Researchers have also begun to study how projected future increases in drought frequency might affect ecosystems. “Our current review article in Biology of Global Changehighlights that drought can have powerful impacts on ecosystems that can change the way ecosystems respond to subsequent droughts,” says Bahn. For example, in a long-term drought experiment conducted by Deutsche Bahn, it was observed that recurring drought changes the composition of the soil microbial community and unexpectedly makes the soil less susceptible to drought. In their paper, the authors conclude nature communication that recurring drought changes the ecological memory of the soil. This could increase the resilience of ecosystems to future droughts. In another recent article in scientific advancesthe researchers showed that drought affects soil bacteria and fungi differently and favors soil pathogens. Scientists showed that this shift in soil communities can alter the way in which biodiversity cushions the impact of drought on ecosystem productivity.
Biodiversity increases the stability of ecosystems because different species have different ways of dealing with environmental stress. For example, Bahn and colleagues observed that fast-growing plant species in mountain meadows tend to be more sensitive to drought but also recover quickly; slow-growing plants are more resilient, but recover more slowly. In the soil, it is the fungi that are more resilient, while bacteria can recover quickly after drought. During rewetting, bacteria release nitrogen, which benefits fast-growing plants. “Plant-soil interactions are important mechanisms underlying ecosystem responses to drought,” explains Bahn. He also emphasizes the importance of promoting biodiversity when managing ecosystems: “In order to strengthen the resilience of ecosystems to climate change, we must move away from the preference for monocultures such as the widespread spruce forests in Austria.”
Climate neutrality is the most important measure
Deutsche Bahn was recently involved in the scientific advisory board of the Austrian Climate Council. 100 citizens, who were selected to be statistically representative of the Austrian population, identified possible measures to achieve climate neutrality by 2040. Deutsche Bahn found that citizens had a great interest in actively and constructively dealing with the issue of climate change and deal with adaptation.
“Politicians should not underestimate the willingness of citizens to support measures to contain the climate crisis,” says Bahn. “While taking action to protect and enhance biodiversity are important steps to increasing climate resilience, there is an urgent need to take swift action to slow climate change. This is the main reason for the recent and upcoming increases in the frequency and intensity of droughts.”