Effects of extreme weather events on Apennines grasslands productivity.

Extreme weather events are expected to increase in frequency and magnitude due to climate change especially on Mediterranean chains, but their effect on ecosystem services and vegetation processes are widely unknown. Prediction of future impacts has become critical to conservation planning and management, particularly in protected areas. Our research has been carried out in the Torricchio Nature Reserve (Central Apennines, Italy), 317 ha under strict protection since 1970, owned and managed by the University of Camerino. Two contrasting grassland ecosystems under different environmental conditions (North and South facing slopes) were selected to simulate extreme events. The magnitude of a given recurrence interval (1000 year) were estimated by the application of extreme value distributions on climate data series covering 50 years. In both slopes, the weather manipulations consisted of extreme drought (D), additional rainfall (R) and ambient conditions for control (C). The experiment covered 2 years (2011 and 2012). Once a year, at the end of the treatment period, the above-ground biomass was collected. No significant differences between treatments were found in the productivity of the stony terrain of the S facing slope, while significant results were detected between the climatic extremes (D vs R) in the N facing slope with dense plant cover. In any case, the experimental treatments of the S facing slope, show a high level of biomass variability, demonstrating the importance of the fine-scale environmental heterogeneity. The effects of climatic alteration on productivity of montane grasslands, underlines the crucial importance of future research on the outcome of climate change in these systems.