VULCAN: a European field scale manipulation project to assess the vulnerability of shrubland ecosystems under climatic changes

European shrubland ecosystems are vulnerable to various environmental stress factors. Climate change will lead to higher night time temperature, more vigorous rain storms and extended droughts which will likely have impacts on ecosystem functioning in European shrublands. VULCAN investigates these impacts by experimental manipulations of 6 shrubland ecosystems in Europe (Denmark, the Netherlands, united Kingdom, Spain, Italy and Hungary) and studies of the effects of warming and drought on plant, soil, fauna and soil water processes. Temperature manipulations are done by a newly developed approach - night-time warming, where a aluminium curtain is drawn over the vegetation at night to reduce the loss of long wave radiation to the atmosphere. In average the plants and soils are heated by 1-2 oC. Drought is created for 2 months in the start of the growing season by a corresponding retractable plastic curtain. The drought covers are controlled to cover the vegetation only during rain events. Both of these manipulation techniques have very low levels of influence on other important growth factors such as light, wind and moisture, and therefor artefacts are small compared to most other approaches to create warming and drought at the field scale.