Impact of extreme weather events on soil microbial community composition and emissions of climate-relevant gases

Extreme weather events involve risks that go beyond their immediate threat to ecosystems to possibly even feeding back in to climate change. Sonja Leitner’s research focuses on such a scenario. As drought periods are projected to become longer and heavy rainfall events more frequent, this will undoubtedly affect Earth’s soils. That’s why Leitner is simulating extreme weather conditions in a beech forest in Austria. Using roofs that prevent rain from reaching the soil at times, and sprinklers that simulate heavy rainfall at others, she tests the effects on soil aggregate stability, nutrient cycles, microbe populations and emissions of greenhouse gases like carbon dioxide, methane and nitrous oxide.
After two years of experiments, her data already show that certain microbial groups are much more active after rewetting events. This results in a flush of nutrients that can be lost from the forest soil and cause problems in other ecosystems, like groundwater contamination and eutrophication of rivers. In addition, CO2 emissions decrease significantly during extended drought periods, although they increase during the first 48 hours post-rainfall. These results show that forests are highly susceptible to climate change effects and respond rapidly to changes in precipitation patterns. Leitner’s work brings new knowledge to climate models and decision-making around a number of climate-related topics, like forest management, climate change mitigation, and environmental preservation.