Research Reports

Small-scale Patterns of Occurrence of Snow Pratia Pratia gelida
at Hospice Plain, Mount Buffalo National Park

John Morgan, Susanna Venn, Lynise Wearne, Max Bartley and Sharne McMillan

Abstract
The broad habitat and small-scale microsite requirements of the rare perennial subalpine herb Snow Pratia Pratia gelida (Lobeliaceae) were investigated at Hospice Plain, Mount Buffalo National Park. Permanent transects were established in two populations occurring in a Poa costiniana wet tussock grassland community and a Carex gaudichaudiana fen and the local patch type, soil depth, soil pH and topography determined at small spatial scales. The occurrence of P. gelida at both sites was strongly and positively associated with the presence of bare ground on organic soils maintained by (a) frost heave or (b) creek-bed scouring. Whenever intense competition from adjacent herbs, grasses or shrubs occurred, P. gelida declined in abundance, suggesting that it is a poor competitor for space and/or resources such as light. Hence, the maintenance of bare ground patches by natural processes appears critical to the on-going persistence of the species. Additionally, P. gelida distribution was strongly favoured by local-scale topographic depressions, suggesting that water availability is also important. Invasion of bare ground patches by non-native species such as Brown-top Bent Grass Agrostis capillaris and Yarrow Achillea millefolium was observed and hence, potentially constitutes a threatening process. Pratia gelida is amongst the rarest of subalpine plants given its (a) restricted distribution, (b) restricted habitat and (c) small-population size and it warrants on-going monitoring to ensure that the dynamic population processes we predict are maintained.
(The Victorian Naturalist 120 (1), 2003, 4-9)

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Reproductive Characteristics of Road-verge and Reserve-interior Populations
of Exocarpos cupressiformis Labill. (Santalaceae)

Brad R Murray

Abstract
Fragmentation of native vegetation by roads exposes species to the conditions of a different surrounding ecosystem where the road verges onto the original habitat. An important issue for conservation biology is how native species respond to these human-made ecosystems. In this study I compared reproductive characteristics, including seed output, seed mass, predispersal seed predation and dispersal appendage mass, between road-verge populations of the woody perennial, Exocarpos cupressiformis Labill., and nearby populations within undisturbed vegetation, in the Black Mountain Reserve in Canberra (Australian Capital Territory). Road-verge populations produced significantly more seeds per area of canopy cover and tended to have larger dispersal appendages than non-verge populations in the reserve interior. There were no significant differences in seed mass or levels of predispersal seed predation between road-verge and reserve-interior populations. However, seed mass and predispersal seed predation varied significantly among populations within the two locations. These findings demonstrate that populations of E. cupressiformis in disturbed habitats on road verges had an increased capacity for colonisation and a higher potential rate of increase through greater seed output and a tendency for larger investment in dispersal.
(The Victorian Naturalist 120 (1), 2003, 10-14)

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The Potential Impact of Climate Change on Plant Communities in the Kosciuszko Alpine Zone

Catherine Marina Pickering and Tristan Armstrong

Abstract
The potential impacts of increased temperatures, decreased precipitation and decreased duration of snow cover over the next seventy years are evaluated for twelve plant communities in the Kosciuszko alpine region of Australia. The approach taken is speculative and provides a series of hypotheses about potential patterns of change. The short alpine herbfield and snowbank feldmark communities are likely to be negatively affected by the predicted declining snow cover, as snowbanks become fewer and smaller. Windswept feldmark, however, may become more widespread if snow cover declines, exposing new areas to freezing temperatures, high winds and resultant loss of soil cover. Climate change initially may have a beneficial or neutral effect on the tall alpine herbfield. If snow cover continues to decline below 3-4 months per year, as is predicted, then the tall alpine herbfield could eventually decline in area. Bogs, fens, raised bog and valley bog communities are likely to vary in area as changes in precipitation, runoff and evaporation alter the competitive ability of plant species belonging to these communities. Heath communities are likely to increase in area as increasing temperature and declining snow cover favour shrub species over grasses and herbs. Increasing diversity and abundance of alien plant species within the alpine zone are likely to continue and may be amplified by climate change.
(The Victorian Naturalist 120 (1), 2003, 15-24)

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