A PORTABLE DEVICE FOR THE SIMULATION OF AIR FROSTS AT REMOTE FIELD LOCATIONS

1. Natural late frosts can have important ecological and economic effe cts. A device is described which can simulate night-time air frosts at remote, field locations. It is composed of an insulated cloche, vorte x tubes and a compressed air generator. Vortex tubes are commercially available devices that split a single compressed air stream into two, one hot and one cold. 2. In a pilot study, five replicate 2 x 2 m area s of grassland on a limestone slope in Derbyshire were subjected to a -2.8-degrees-C (range +/- 1.1-degrees-C) air frost for 3 h in early Ju ne 1992. 3. Initial subjective observations on the vegetation suggeste d that the effects were similar to those of natural late frosts observ ed in previous years. The device is currently being used in long-term, climate change studies at the Unit of Comparative Plant Ecology (UCPE ).