The role of native and range-expanding plant communities in buffering the effects of drought on soil functioning

Climate change is altering the composition of plant communities at high altitudes and latitudes by enhanced extreme events, range shifts and de-coupling of co-evolved trophic interactions. Previous research has shown that invasive plant species and abiotic stressors can change carbon and nutrient cycling at local scales. However, it remains unclear whether novel communities formed by range-expanding plant species also alter soil functions in the new ranges and what roles enhanced incidence of drought stress play in these novel communities. We tested the hypothesis that plant species that shift range from southern to northern Europe have greater resistance and resilience under extreme drought events, especially in the presence of southern soil communities.
Plant communities of range-expanding and related native species were planted in a multi-year mesocosm experiment outside. In 2016, we applied a 6-week summer drought to half of the mesocosms. Soil samples were collected before, during and after drought. We measured the functioning of soil communities (e.g. litter decomposition, carbon mineralization and soil enzymatic activities) to quantify their resistance and resilience to drought stress. Our results assess the interactions of plant range-expansion and drought stress on key ecosystem processes. Results will be presented and we will discuss how effects of climate change may interact with effects of range shifts.