Effects of Global Change on Peatland Ecosystems

The aim of this thesis is to evaluate the effect of global change on peatlands. Peatlands are ecosystems in which the rate of decomposition of organic matter is slower than the rate of accumulation. This feature has important implications for carbon cycling. In effect, peatlands store one third of terrestrial carbon. The thesis consists of five studies. The first study is focused on the use of Plant Functional Types (PFTs) in order to investigate the foliar nutrient concentrations in mire ecosystems. The PFT approach can help us understand how environmental changes associated with climate warming will affect terrestrial ecosystems either through direct effects on ecosystem functioning or through indirect effects mediated by compositional changes in vegetation. The aim of the second was to determine the aboveground net primary production (ANPP) of different mire types in the Southern Alps of Italy in order to detect whether ANPP patterns along the poor-rich gradient could be related to the limiting effects of one or several nutrients for biomass production. The third study investigated relationships among peatland hydrology, vegetation and ecological patterns in this region. As the ecological features and, eventually, the very existence of peatlands closely depend on amount and quality of water input, it is important to understand how hydrology controls vegetation composition and ecosystem functioning in these habitats. The latter point is, in turn, a fundamental basis for any policy of peatland conservation and/or restoration. The fourth study is an experiment on the effects of snow cover on peatlands. Snow cover is an important environmental factor that influences ecosystem functioning. The fifth work has been carried out in Canadian peatlands in collaboration with the Prof. Waddington from the School of Geography and Earth Science of McMaster University (Ontario) and it has been inserted in a wider project named Peatfire. I investigated the effect of trees on evapotranspiration in feathermoss and Sphagnum sp. Each study reported in this thesis is important in order to understand the different facies of the global change.