Sixteen 1-ha study plots covering five regeneration stages were simultaneously trapped five times over a 20-month period to provide data on small mammal response to vegetation changes following fire. Areas regenerating a fier fires from 9 years to 1 month before the investigation were sampled in a uniform open forest on a coastal sand plain. Two types ofunderstorey were recognized: one dominated by true forest shrubs with which Rattus fuscipes, Antechinus stuartii and Sminthopsis murina were associated, and another dominated by heath elements where the addition of Pseudomys novaehollandiae and Mus musculus produced a significantly more diverse small mammal community. The two communities exhibited different responses to post-fire vegetation changes.Rattus fuscipes was the most abundant species and showed a logistic growth in biomass. No resident populations were established in the first 3 years, but a rapid increase in biomass occurred from 3 to 5 years to plateau a fier 8 years. Regeneration age had the greatest effect on R. fuscipes biomass mediated through the amount of accumulated leaf litter with additional variation being attributed to several vegetation structure variables and plant species diversity.A replacement sequence in time was observed for species reaching their maximum abundance (P. novaehollandiae and/or M. musculus -* S. murina -» A. stuartii -» R. fuscipes) and was interpreted as species occupying stages in the suc-•Present address: cession when their optimal habitat requirements were fulfilled. These results have important implications for the design of management policies using fire or fire regimes as tools for habitat maintenance or alteration. A mosaic of forest patches of adequate size covering the entire range of serai stages is necessary to meet the optimum requirements of all the above species.
The rate of accumulation and the composition of the forest floor litter were studied in an open eucalypt forest at Seal Rocks, New South Wales. The forest is subject to frequent fires and its recent fire history is well documented. The height of the understorey vegetation was shown to be a good indication of the time since fire. Litter accumulation in eucalypt forests can be adequately described by a modified exponential equation with two parameters, steady-state accumulation (Χss) and rate of accumulation (k). Both parameters are functions of the annual litter fall, which is assumed to be continuous in this model. The steady-state accumulation of litter in the Seal Rocks forest was found to be 1.67 kg m-2, reached after c. 10 years. The model should be recognized as a gross simplification of the many factors which affect litter accumulation, in particular the assumption of a constant value for k. The components of the litter on the forest floor change in relative importance with time owing to differing rates of accumulation and decomposition.
The taxonomic status of distinctive populations of the widespread and morphologically variable possum Trichosurus vulpecula was examined. For the analysis, morphological characters (body size, fur colour and skull dimensions), karyotypes, electrophoretic allozyme, and ecological data were compared for as many Trichosurus populations as possible. There are insufficient differences between populations of T. vulpecula to reject a null hypothesis that they comprise a single species. Tasmanian, northern and south-western Australian populations could be retained as subspecies, but insufficient data exist to resolve the specific status of Atheton Tabeland and north-eastern Australian populations. One enigmatic result is that the skull morphometrics and allozymes of T. caninus were not distinguishable from those of sympatric T. vulpecula. However, other morphological characteristics and ecological data provide adequate evidence the T. caninus is a distinct species.
Comparison among eight pseudocheirid species and two outgroup petaurids were made by means of the hydroxyapatite chromatography method of DNA hybridisation. Matrices of DELTAT(m) and DELTAT(m)H-C values were analysed with the FITCH algorithm in Felsenstein's PHYLIP (Version 3.3). Jackknifing and bootstrapping were applied to determine the stability of resulting topologies. All the phylogenetic analyses produced trees that support (1) the monophyly of the Pseudocheirus herbertensis complex, (2) the monophyly of Pseudocheirus, (3) a close relationship between Hemibelideus and Petauroides, and (4) a close relationship between Pseudochirops archeri and Pseudochirops cupreus. Rates of single-copy DNA evolution are slightly faster in Pseudocheirus, Hemibelideus, and Petauroides than in Pseudochirops. Hybridisation evidence also provides a framework for understanding the timing of the pseudocheirid radiation and suggests that the divergence between extant genera dates back to about 36 million years ago.
Microcomplement fixation of albumin was used to examine the phylogenetic relationships among the ringtail possums, family Pseudocheiridae. Phylogenetic analysis of the data supports the hypothesis of at least three distinct clades within the family: one containing Petauroides and Hemibelideus; a second consisting of Pseudocheirus herbertensis, Ps. forbesi, Ps. mayeri, and Ps. canescens; and a third containing Ps. archeri, Ps. corinnae, Ps. cupreus and Ps. dahli. The data have not resolved the phylogenetic position of Ps. peregrinus, which may either form a separate clade or lie close to the Ps. archeri clade.
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