ADAPTATIONS OF 3 SPRINGTAIL SPECIES TO GRANITE BOULDER HABITATS (COLLEMBOLA)

1) Small spots of low vegetation on granite boulders in northern Austr ia are inhabited by a characteristic collembolan coenosis. Ecophysiolo gical properties of three frequent boulder-dwelling springtail species (representing two different life forms) were tested in field and labo ratory experiments and related to the specific life habits. (2) The eu edaphic Onychiurus armatus lives exclusively in climatically stable pl ant cushions typically connected to the surrounding soil by moss strip s. This habitat preference reveals the strict requirement of this spec ies for moisture, its modest supercooling ability, and an aversion to crossing bare rock. (3) Pseudisotoma sensibilis and Xenylla boerneri a re corticophilous springtails of hemiedaphic life form. Ps. sensibilis prefers cushions not far above the ground and frequently migrates bet ween rock and soil. X. boerneri, the dominant species in the climatica lly unstable cushions on top of boulders, is also able to cross dry ro ck surfaces; it can, however, survive harsh periods in these cushions due to its pronounced drought resistance and the cold hardiness of the majority of the population during winter.