Swiss environment ministry researchers have begun a detailed tri-annual survey of forest health in the confederation. To be reported next spring, the new figures will reveal whether an established worsening trend has continued. Between 1985 and 1994, the proportion of trees that had lost over a quarter of their leaves doubled to over 18%, a trend described by the ministry as "alarming". Coordinated by the Swiss Federal Institute for Forest, Snow and Landscape Research, the investigation will look at more than 4,000 trees in 8x8 kilometre grids. This is twice the density of annual surveys carried out in all European countries under the convention on long-range transboundary air pollution, and provides a better indication of real trends, according to Dr John Innes of the institute. Dr Innes told ENDS Daily that the observed leaf loss is caused by stress, but that the reasons remain unclear, and could include soil acidification, air pollution or drought. The institute has launched a special study to determine the causes of tree sickness in specific areas and for specific species.
Swiss Federal Institute for Forest, Snow and Landscape Research, tel: +41 1 739 2215.
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