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Climate is changing, so will ecosystems & the landscape: Experimental evidence

Monday, September 29, 2014, 12:00PM - 1:00PM


Alexandre Buttler

Laboratoire des Systèmes Ecologiques, Lausanne, Switzerland

Global warming and associated environmental changes are predicted to have a strong impact on mountain ecosystems this century. Silvopastoral systems of the Swiss Jura Mountains serve as a traditional source of forage and timber in the subalpine vegetation belt, but their sensitivity to historic land­‐use and climate change puts their future sustainability at stake. The observed trend in Swiss mountains during the 20th century for a 1.5°C rise in mean annual air temperature is paralleled by increased instances of extreme summer temperature maxima and prolonged droughts. Throughout the current century, these tendencies are predicted to become more pronounced, and Northern Hemisphere temperate mountains will experience the most intensive temperature rise, with a rate of warming typically two to three times higher (range +2.8°C to +5.3°C) than that recorded over the 20th century. This will bring about changes that would ultimately have repercussions on ecosystem distribution and function.

The presentation will give an overview of some experimental work done along an altitudinal gradient. Turf mesocosms from three habitats in wooded pastures were transplanted downslope, from 1350 m a.s.l. (control site), down to 1010 m a.s.l. and 570 m a.s.l. respectively, testing for their resistance to three intensities of climate change. Plant biomass, species diversity, vegetation phenology, litter decomposition, but also soil properties such as soil respiration, net ecosystem exchange, microbial biomass and carbon loss in drainage water were measured. A special attention was given to processes in winter under snow. Finally, some data were used to calibrate a spatially explicit vegetation dynamic model of forest-­grassland mosaics.