The effects of the opening of a construction site on high- mountain tree vegetation

upper Valtellina since the 1920s. The "New Viola Canal", which was inaugurated in the summer of 2004, is one of several works being created as part of AEM's modernization plans. The canal is situated in a high altitude area of great environmental importance, partially located inside Stelvio National Park. The works leading up to the opening of the construction site being examined here concern the creation of a new water diversion canal to substitute the previous one, and aimed at increasing electrical power production. The “New Viola Canal” is about 15.8 km long and it has been built at an altitude ranging from 1900 to 2000 m a.s.l. The structure is entirely enclosed in a tunnel beginning in Val Verva at an altitude of 1993 m and ending at the outlet in Cancano lake (Val Fraele) at an altitude of 1900 m. The Cancano lake outlet works consist of a tunnel access portal and a structure for channeling the water flow towards the lake. The outlet works are open-air works and will eventually be covered as far as the end of the inlet chute into the reservoir (fig. 1). The construction site occupies a surface area of about 2800 m 2 . The work being carried out in this area is mainly related to the drilling equipment as its progresses and the unloading, stocking and handling of the debris material from excavation of the tunnel. Lastly, there is a concrete-mixing plant that is directly connected to the railway line, as well as structures serving to reduce environmental impacts. That is a screen in the materials unloading zone to minimize dust emission in the area and a treatment system for waste water and sludge, which are released into the lake.