FLORA AND VEGETATION OF THE KUSNACHTERTOB EL - CHANGES IN THE LAST 50YEARS

The flora and vegetation of a small ravine near Kusnacht (eastern Swis s lowlands) as reported for the year 1937 is compared with the actual situation in the year 1993. In the course of the last fifty years 37 s pecies have disappeared within the studied area. Most of these species usually grow in nutrient poor grassland communities (Mesobromion), in chalk wetlands dominated by small sedges (Caricion davallianae), and in sparse forests. The limits of an adequate interpretation of the und ertaken floristic comparison are discussed. The decline of species abu ndance is connected with intensive agricultural management, draining o f wetlands, and the lack of disturbance (absent erosion) as a result o f river breaks and other protective measurements. The importance of si te dynamics for the conservation of endangered species, especially pio neer species and glacial relicts, is stressed.