Detailed rules concerning the protection of the Community's forests against atmospheric pollution are set out in Commission Regulation (EC) No 836/94 of 13 April 1994. The Regulation amends an earlier Regulation to include new sampling and survey measures. The condition of the Community's forests continues to give cause for concern. Steps should therefore be taken to extend the surveys on the established network of observation plots in a coordinated and harmonized way. The amendment introduces an optional survey on the chemical content of needles and leaves, to provide basic additional information on the health of forest ecosystems. Such sampling is essential in the demonstration of possible limited mineral nutrition. Member States participating in this survey, shall forward to the Commission by 30 June 1996 in a standardized form the data collected and analysed for each observation plot.