COS 37-8
Latitudinal effects of species interactions and genetic diversity on climate-change resilience of experimental bog plant-communities
The persistence of species under changed climatic conditions depends on adaptations, plastic responses and on biotic interactions at the local scale. Particularly, populations at species’ range-margins may be crucial in containing a gene pool comprising adaptations to extreme climatic conditions. Many species of northern European bog ecosystems reach their southern lowland range-limit in Central Europe. In a common-garden experiment, we assessed the impact of projected climatic changes on five bog-plant species (including the peat moss Sphagnum magellanicum and the sedge Carex limosa) sampled along a latitudinal gradient of 1400 km from Scandinavia to the marginal lowland populations in Germany. Populations were cultivated in monocultures and experimental communities composed of all five species from their local community and exposed to three climate treatments (increased temperature, increased variability in soil-water table, increased fertilization) in a southern common garden. Genetic diversity within and among populations of S. magellanicum and C. limosa was assessed using microsatellite analyses to infer effects of genetic diversity on responses to increased biodiversity and climate treatments.
Results/Conclusions
Whereas most monocultures showed decreasing biomass production from southern to northern origins under southern environmental conditions, an increasing biomass was observed towards northern origins within the experimental communities concomittant with a shift in interspecific interactions along the latitudinal gradient: While negative dominance effects prevailed in southern communities, higher net biodiversity effects were observed in northern subarctic communities. Particularly, northern populations of S. magellanicum benefited from biodiversity effects. Our microsatellite analyses discovered two new cryptic species within S. magellanicum with occurrences in both Central and Northern Europe. However, responses to increased biodiversity were neither affected by genetic identity nor genetic diversity. Microsatellite analysis of C. limosa did not reveal clear genetic clusters and no contrast in genetic diversity between northern core and southern edge populations. The combined effects of climate treatments increased biomass production in monocultures, but not in the experimental communities, where, overall, the climate treatments did not result in significant effects. In southern communities, however, specific climate treatments such as water-table fluctuations significantly decreased biomass production.
Differences in interspecific interactions instead of differences in genetic diversity caused pronounced responses to changed climatic conditions in wetland communities and should be considered an important factor influencing community responses to climate change.