Overwintering ecology of alpine Collembola and oribatid mites from the Austrian Alps

. 1. Collembola and oribatid mites from windswept mountain ridges at about 2700 m a.s.l. in the Austrian Alps were all killed by freezing, and depend on supercooling to survive low winter temperatures. The Collembola Tetracanthella afurcata Handschin, Xenylla acauda Gisin and Isotoma spp. collected in January had average supercooling points between ‐25 and ‐29°C, and the oribatid mites Fuscozetes fuscipes (Koch) and Lepidozetes singularis Berlese of about ‐28 and ‐31°C respectively. The ability to supercool was not increased during storage at ‐5°C, and was generally lower in species collected in March. 2. The oribatid mites Fuscozetes intermedius Caroli and Maffia, F. fuscipes, Damaeus diversipilis (Willmann) and L.singularis contained from 9 to 16 μg glycerol per mg fresh weight after storage at ‐5°C, while no glycerol could be detected in the Collembola Isotoma spp., T.afurcata and Onychiurus vontoernei Gisin. 3. Activity below 0°C was observed in T.afurcata and O.vontoernei , which had chill‐coma temperatures of ‐7.7 and ‐4.9°C respectively. 4. Some specimens of F.intermedius survived more than 90 days of anoxia at 0°C, T.afurcata up to 60 days and O.vontoernei up to 24 days. 5. The overwintering biology of Collembola and oribatid mites from the Austrian Alps appears similar to that of Norwegian species, except that those from Austria have slightly lower supercooling points and higher contents of glycerol.