Growth of Subalpine Shrubs and Snowgrass Following a Rare Occurrence of Frost and Drought in Southeastern Australia

Abstract

From March 1982 to March 1983, the subalpine tract of the Bogong High Plains in southeastern Australia was subject to a series of unusual climatic events. Relatively severe frosts occurred during autumn and winter, snow cover during winter was low, and the 1982/83 summer was particularly dry. This combination of frost and drought is the only one recorded over the past 50 yr. The net annual aboveground production of the dominant shrubs from open grassy-heath and closed heath communities ranged from 480 to 830 g m-2 yr-', with greater production by shrubs within more sheltered, closed heath communities. These values were considerably greater than those of snowgrass (Poa sp.) within grassy swards in these two community types, (135 g m-2 yr-'). Such a combination of climatic events may have longlasting effects, and in particular may favor the growth of the shrubs over snowgrass where these two different life forms are competing within the shrub-grass complex.