Open Access

John W. Morgan

• Subalpine shrubs on rocky slopes on the Bogong High Plains, Victoria (36° 53’ S, 147° 19’ E), were observed to be severely desiccated over the summer of 2002/03 after a 50 day period when only 1.2 mm of rainfall was recorded. Moderate to severe canopy dieback was noted in shrubs growing on rocky north- and west-facing slopes. Four shrubs were assessed for their drought tolerance on west-facing slopes at Basalt Hill. Soils were rocky and uniformly shallow across the site (mean depth = 11.32 ± 0.69 cm). Prostanthera cuneata was the most drought tolerant species (as evidenced by the least amount of canopy dieback observed) followed by Hovea montana, Pimelea axiflora var. alpina and Epacris glacialis. All Epacris glacialis plants (n = 16) had died at the study location whereas no Prostanthera cuneata plants (n = 45) had canopy dieback that exceeded 60%. The amount of dieback observed was not significantly associated with either local soil depth or shrub canopy area. Hence, very small plants were not more susceptible to drought nor were shrubs found on the shallowest of the soils at the site. This suggests that drought effects are possibly dependent on local influences such as topography, drainage and competition intensity. Drought has only rarely been considered a major factor affecting the abundance and distribution of subalpine shrub species in Australia but this study suggests that it should be added to the list of abiotic factors governing the local dynamics of subalpine vegetation. In particular, the high mortality of Epacris glacialis observed in the study area suggests that non-equilibrium dynamics are likely to be the "norm" for some shrubs in subalpine areas.