In the mire of la Vraconnaz, located at a mean altitude of 1090 m there was a bog burst in September 1987 after an extraordinary spell of heavy rainfall. The vegetation that was affected by the slide includes various groups of bog plants as well as groups of acidic and alkaline fen plants. Over 6 years the development of this vegetation was monitored on 100 permanent plots. Floristic composition and indicator values were analysed and compared in 1988 and again between 1991 and 1993. Indications of a change in the vegetation pattern are only discernible in the groups of acidic fen vegetation. It may be due to drier conditions, eutrophication and the closing of the herb cover. The stability of the other groups can partly be explained by historical factors. The recolonisation of the bare peat surface progresses slowly and with random settlements at first. Although the slide had been a great disturbance, the observation period was too short to allow the definition of any plant succession patterns.