Effects of Rabbit Grazing and Fire on a Subalpine Environment. II. Tree Vegetation

Abstract

The effects of two low-intensity fires andlor grazing by rabbits and wombats upon trees of Eucalyptus pauciflora and E. stellulata. in a subalpine environment were studied between 1977 and 1984. The experimental plot design permitted comparisons to be made between unburnt and burnt areas, each of which was subjected to four grazing regimes. Tall shrubs, mainly Bossiaea foliosa, which were present under the trees during the first fire but not the second increased fire intensity and flame height and hence damage to trees. The first fire in March 1978 did not completely kill any trees, but killed all the stems 2 m or more in height on 34% of trees and stimulated basal regrowth on a further 17% without killing all the stems. The first fire also reduced the basal area of live stems by about 17%. Small saplings less than 2 m high and seedlings were generally top-killed but resprouted from the base. In the second fire only lignotub- erous regrowth and seedlings were affected as they were in the first fire; the older trees showed no sign of damage. Rabbits killed a significant number of trees by first ring-barking the stems and then grazing the regrowth. Both the fires facilitated the establishment of tree seedlings in the frost-hollow by exposing bare soil, but few of these seedlings survived to the end of the 7-year study period. Frost was probably the main cause of tree death, but drought and competition from other species may also have contributed to losses.

Lignotuber reserves support regrowth following clipping of two Mediterranean shrubs

“…Multiple‐disturbance scenarios bring an important ecological consideration to understanding the evolutionary origin of the lignotuber whose acquisition is thought to be mediated by disturbances as a selective pressure. Multiple disturbances are particularly significant in fire‐prone ecosystems (Zedler, Gautier & McMaster 1983; Christensen 1985) and in environments where fire events are followed by herbivory on the highly palatable new resprouts (Davis 1967; Wimbush & Forrester 1988; Thomas & Davis 1989; Moreno & Oechel 1991). In our study, all lignotuber resources (starch and nutrients) were heavily depleted after multiple clippings.…”

Does alpine grazing reduce blazing? A landscape test of a widely‐held hypothesis

“…Fire is rare in Australian alpine and subalpine environments, with major conflagrations occurring in any one place only once or twice per century (Kirkpatrick & Dickinson 1984; Leigh et al . 1987; Wimbush & Forrester 1988; Banks 1989; Wahren et al . 2001; Williams et al .…”

Early post‐fire regeneration in subalpine heathland and grassland in the Victorian Alpine National Park, south‐eastern Australia

“…The natural fire regimes of the treeless high mountain vegetation of Australia are difficult to quantify, and the role of fire in the dynamics of alpine and subalpine vegetation in Australia is largely unknown. At the landscape scale (that of square kilometres or more), fire appears to be relatively rare in these environments (Kirkpatrick & Dickinson 1984; Leigh et al 1987; Wimbush & Forrester 1988; Williams & Costin 1994). Given that few fires have occurred in alpine and subalpine vegetation, knowledge of post‐fire ecology, especially initial impacts and early responses, in alpine and treeless subalpine vegetation is also scant.…”