bluuebunny/crossref_metadata_2025 huggingface dataset:
The influence of intensive sheep grazing on genotypic differentiation in Danthonia linkii, D. richardsonii and D. racemosa on the New England Tablelands
Authors: SCOTT A. W. , WHALLEY R. D. B.
Published: July 2006

Genotypic differentiation studies involving three native pasture grasses Danthonia linkii Kunth, D. richardsonii Cashmore and D. racemosa R.Br. were made, using populations both collected from the field and grown from selfed seed, to investigate the influence of the intensive grazing and high soil fertility associated with sheep camps on a number of morphological and developmental characters. Each species was represented by at least a pair of populations one of which was sampled from a sheep campsite, the other(s) from an adjacent site as close as possible to the camp but outside its influence.

The sheep camp populations were generally more prostrate with shorter tillers, greater tiller numbers, later flowering time, and in one population group, a larger number of seeds set. These differences were more apparent in the parent populations collected from the field but grown under uniform conditions than in the F1 populations produced from selfed seed.

These population differences were interpreted as representing genotypic differentiation produced by intensive selection pressures introduced since the development of the sheep camps. They were certainly more intensive in populations drawn from sheep camps which had been in existence for a longer time. The selection pressures which produced the new populations also appeared to maintain a broad base of genetic variability rather than result in populations more uniform than the original.
Length‐weight relationships for invertebrates from forests in south‐eastern New South Wales
Authors: GOWING G. , RECHER H. F.
Published: July 2006

The relationship between length and weight was calculated for nine taxa of eucalypt forest and woodland invertebrates from south‐eastern New South Wales. Length and weight were highly correlated. For the majority of taxa the relationship was best described by a power model. There were no significant differences between the length‐weight regressions of Australian and North American taxa. This strengthens the value of generalized regressions for estimates of biomass from invertebrate length data in ecological studies.
The influence of insects on nutrient cycling in eucalypt forests: A beneficial role?
Authors: LAMB DAVID
Published: July 2006

Insect herbivory is common in many Australian eucalypt forests and, some have suggested, may be greater than in comparable forests overseas. It has been hypothesized by several authors that herbivores max nutritionally advantage either individual plants or plant communities by hastening the biogeochemical cycling of nutrients. This coevolutionary development, it is argued, would be a particular advantage in poor soils. These suggestions conflict, however, with evidence that eucalypts commonly conserve nutrients by nutrient withdrawal prior to leaf abscission and recycling a considerable proportion of nutrients through an internal biochemical cycle.

The various hypotheses that have been proposed are reviewed. Although there are some situations both at the individual and community level where herbivory may confer nutritional advantages it appears unlikely that high levels of herbivory in eucalypts are generally nutritionally beneficial to the plants being grazed.
Immediate effects of Ore on ants in the semi‐arid mallee region of north‐western Victoria
Authors: ANDERSEN ALAN N. , YEN ALAN L.
Published: July 2006

The immediate effects of a high intensity wildfire on the ant communities of a heath and a mallee site in semi‐arid north‐western Victoria are reported. Following fire the number of species trapped on the ground doubled (to ca. 80 each site), total ant abundance decreased by half (due to the demise of previously dominant species), surface activity of reproductive castes increased, and dramatic changes in species relative abundance (including shifts toward greater equitability) occurred. These changes are interpreted in terms of fire‐induced simplification of the habitat and release from competition with dominant species. The results appear to illustrate the importance of interspecific competition in structuring foraging activity in mallee ant communities. Observations are also reported on seed‐harvesting by ants, including changes in harvester ant abundance, germination from within‐nest seed storage, and the first record of Heteroponera removing seeds.
Further discussion of Phyllocladus and its pollen in Victoria during the Holocene
Authors: HEAD LESLEY
Published: July 2006

Phyllocladus pollen was not identified in mid‐late Holocene sediments in the Otway Ranges but has been found, in western Victoria, in a surface sample and in lake sediments probably younger than 1100 BP. These results refute the view of Churchill and Dodson (1980) that Phyllocladus was present in western Victoria (probably in the Otway Ranges) through the Holocene until dry conditions caused its extinction about 1100 BP. It is concluded that the Phyllocladus pollen in western Victorian Holocene deposits is derived from sources in Tasmania and/or New Zealand.
Fecundity and fertility in Latrodectus hasselti (Araneae: Theridiidae)
Authors: DOWNES MICHAEL F.
Published: July 2006

A total of 216 egg sacs of Latrodectus hasselti Thorell was examined to determine the proportion of infertile or otherwise inviable eggs. This proportion varied greatly between egg sacs but there was no consistent trend towards an increase or decrease in fecundity or fertility in sequences of egg sacs produced by given female spiders. It is suggested that the production of inviable eggs, by providing an early food source, may enable spiderlings to escape from unfavourable areas.
Rainfall in the wet‐dry tropics: Extreme events at Darwin and similarities between years during the period 1870–1983 inclusive
Authors: TAYLOR JOHN A. , TULLOCH DON
Published: July 2006

This paper supplements the existing climatic analyses for Darwin and the surrounding region, by providing a classification of years in terms of amount and distribution of rainfall, and highlighting the extreme, episodic rainfall events that have occurred in the period 1870 to 1983 inclusive. Approximately 77% of years have had significant departures from the two most frequent rainfall patterns and these are described. Much of the variation between years or groups of years lies in the dry and dry‐wet transition periods. While the reliability of rainfall in the wet‐dry tropics has been emphasized, rainfall variability over both the dry and wet seasons would seem to be an equally important characteristic, at least for the biota. In an environment such as the wet‐dry tropics, where moisture is the primary limiting factor, rainfall variability has important implications for the design and interpretation of faunal and floristic surveys, monitoring programs and field experiments.
Variation in serotiny of three Banksia species along a climatic gradient
Authors: COWLING RICHARD M. , LAMONT BYRON B.
Published: July 2006

The degree of serotiny (i.e. the proportion of follicles remaining closed in each year's crop of cones since the last fire) was measured in Bank‐sia attenuata, B. menziesii and B. prionotes at five sites along a climatic gradient extending 500 km north of Perth, Western Australia. The decrease in annual rainfall and increase in average temperature along the gradient paralleled a decrease in plant height and an increase in the degree of serotiny of all species. Extreme serotiny was recorded in the scrub‐heath at the xeric end of the gradient whereas two species were essentially non‐serotinous in the low woodland at the most mesic site.

It is concluded that degree of serotiny is related to the fire characteristics of the site which depend on plant height. In xeric scrub‐heath, the entire canopies of the Banksia spp. are consumed by fire which promotes massive release of seed. This facilitates recruitment in an otherwise unpredictable and unreliable seedbed. In mesic woodland, where cones rarely come into contact With flames, seeds are released spontaneously and site conditions are more conducive to recruitment in the inter‐fire period.
Age, reproduction and biomass allocation in Rhopalostylis sapida(Nikau Palm)
Authors: ENRIGHT N. J.
Published: July 2006

Estimates of age, seed production and the pattern of biomass allocation are presented for New Zealand's only native palm species Rhopalostylis sapida. The age at which palms show above‐ground stem development is uncertain, but appears to be in the vicinity of 40–50 years. Palms showing above‐ground stems shed two fronds per year, on average. By counting the number of frond scars an approximate age can be determined.

Seed production increases continuously with size (and age) for palms which exceed a maturity threshold determined by stem height. Although the percentage of total plant biomass represented by reproductive structures is low, seeds may account for over 50% of nikau palm net production in a year.
Relationship between nectar production and seasonal patterns of density and nesting of resident honeyeaters in heathland near Sydney
Authors: PYKE GRAHAM H. , RECHER HARRY F.
Published: July 2006

Some individual honeyeaters were repeatedly seen near the same location over at least a 2 day period and were considered resident in the present study. Such resident honeyeaters (mostly New Holland and White‐cheeked Honeyeaters) were present on the heathland study areas from about February until about October. Production of nectar energy is negligible prior to April and low after October. It is hypothesized that the density of residents is determined by their ability to obtain energy in nearby habitats while establishing nesting sites in the heathland in February and March. Nesting tended to occur between April and July when there was sufficient production of nectar‐energy.
Population dynamics of the shrub Acacia suaveolens (Sm.) Willd.: Dispersal and the dynamics of the soil seed‐bank
Authors: AULD TONY D.
Published: July 2006

Genet survival in seeds of Acacia suaveolens was examined through both dispersal and dormancy in the soil in populations near Sydney.

Following initial passive seed‐fall, the majority of seeds lie within a 1 m radius of the stem of the parent. Further dispersal is predominately mediated by ants. A. suaveolens seeds possess an elaiosome which attracts ants. When elaiosomes are removed, the potential for further dispersal of seeds is greatly reduced. Three species of ant disperse seeds of A. suaveolens and the fate of seeds following ant dispersal was observed to depend on the particular species of ant involved. Ants of both Iridomyrmex sp. and Pheidole sp. B are too small to drag seeds and, instead, ants of these species usually remove the elaiosome in situ, with little dispersal of the‐seed resulting. Ants of Pheidole sp. A are larger and disperse seeds further, frequently taking them into their nests where the elaisosome is removed. Seeds are retained inside the nests and incorporated into the floors and walls of passageways and chambers. Several supposed ‘advantages’ of myrmecochory were examined but none were verified. Instead, two distinct ‘disadvantages’ were identified. These were: burial of seeds by ants of Pheidole sp. A into ‘unsafe sites’; and too deep a burial of seeds in nests for seeds to receive a stimulus to germinate during fires, and for seedlings to emerge successfully. Outside nests of Pheidole sp. A. seeds are concentrated in the top 5 cm of the soil, whilst within nests of these ants, seeds are found up to 15 cm deep.

The dynamics of various components of the soil seed‐bank were examined using seeds buried in nylon mesh containers. The seed‐bank is persistent without annual recruitment to seedlings, enabling a population to persist as seeds after all above‐ground plants have perished.
Movement of the Southern Australian abalone Haliotis laevigata in relation to crevice abundance
Authors: SHEPHERD S. A.
Published: July 2006

The long‐term movement of the abalone Haliotis laevigata was measured at three sites in Waterloo Bay, South Australia, characterized by differing amounts of available crevice space. Movement was negligible at a site where crevices were abundant, but extensive at a site without crevice space. At a site of limited available crevice space, the amount of movement increased as available crevice space decreased. In addition, the extent of movement was size dependent and movement was oriented in the direction of the approaching swell.

Current experimental designs for measuring natural mortality of abalone depend heavily on assumptions about their movement. An understanding of this behaviour is thus a prerequisite for designing experiments to measure the mortality rates of abalone or other sedentary animals.

The natural mortality rate at one site was estimated to be 0.59 (s.e.m. = 0.02, i.e. survival = 56% per year) and the disappearance rate (natural mortality and emigration) was independent of sex.
Influence of grazing management on vegetation, soil structure and nutrient distribution and the infiltration of applied rainfall in a semi‐arid chenopod shrubland
Authors: GRAETZ R. D. , TONGWAY D. J.
Published: July 2006

The experiment utilized a fenceline contrast in vegetation and soil condition that was clearly visible on Landsat imagery. Measurements of vegetation cover, soil structure and chemistry, and infiltration were made. The greatest vegetation change was at the soil surface where the loss of litter and lichen crust cover under heavy grazing accompanied the loss of perennial shrubs. Although grazing caused changes in soil structure and chemistry to less than 10 cm in depth, these changes are quite significant for plant growth. Consistent differences in the infiltration of applied rainfall at two intensities were measured between the grazed and ungrazed sites. At both intensities of application the absence of a lichen crust increased infiltration three‐fold on the heavily grazed site compared with the ungrazed site. The implications of these observations on the long‐term functioning of this landscape are discussed.
The fate of rainfall in a mallee and heath vegetated catchment in southern Western Australia
Authors: NULSEN R.A. , BLIGH K.J. , BAXTER I.N. , SOLIN E.J. , IMRIE D.H.
Published: July 2006

Mallee, a shrub‐eucalypt association, once covered large areas of the cereal growing land in Western Australia. The hydrologic consequences of land development have been more than a doubling of water yield and increased deep drainage beyond the plant‐root zone. The latter has led to large areas of soil salinization.

The uncleared catchment studied was covered with mallee vegetation (65%) and a heath association (35%). Over 12 years of measurement, runoff from the catchment has averaged 0.025 mm per annum with a mean annual rainfall of 376 mm. Half of the runoff resulted from two major events totalling 0.15 mm. Since there was no evidence of groundwater accession in the catchment, the rainfall was balanced by evapotranspiration. Despite virtually no runoff from the whole catchment, considerable internal redistribution of surface water occurred, with localized overland flow in some areas as high as 7.7 mm from 30.9 mm of rainfall in one day.

Rainfall penetrated rapidly under the mallee vegetation and the rate of penetration observed could not be achieved solely through the soil even if there was saturated flow.

A typical stand of native mallee trees (Eucalyptus pileata and E. eremophila) in the catchment effectively redistributed 8% of the annual rain falling on the stand with 3% lost as interception and 5% going to stemflow. However, on an individual tree basis some 15% of the rain falling on the canopy was lost as intercepted water and 25% ran down the stem. The stemflow caused saturated conditions around the bole of the mallee and dye tracing showed that the water penetrated the soil via the annular pathways of the soil‐root interface.

Roots of mallee trees were found at 28 m depth and it is postulated that the mallees are adapted to the semi‐arid environment by virtue of their ability to store water deep in the soil profile for use during the dry summer months.
Development of a new piosphere in arid chenopod shrubland grazed by sheep. 2. Changes to the vegetation
Authors: ANDREW MARTIN H. , LANGE ROBERT T.
Published: July 2006

The initial development of a piosphere created by stocking a new watering trough with ca. 200 sheep at a near‐pristine site in arid chenopod shrubland near Whyalla, South Australia, was studied. The following variables were monitored for up to 8 years using fenced plots as controls:shrub mortality; forage biomass and defoliation of the dominant shrubs and short‐lived grasses; linear dimensions of Rhagodia ulicina; the density of short‐lived species; and the invasion of exotics. Patterns in these variables were looked for which reflected the attenuation of stocking pressure with distance from water; that is, ‘piosphere patterns’.

Piosphere patterns were detected for many variables. Those with values increasing towards the trough were mortality of the main forage shrub Atriplex vesicaria. the density of three short‐lived taxa, viz. the bassias (Sclerolaena obliquicuspis, S. patenticuspis. Maireana sclerolaenoides), Tetragonia tetragonoides, and annual Zygophyllum spp. (Z. crenatum. Z. ovatum), and growth of short‐lived grass species when sheep stocking pressure was low. Variables with values decreasing towards the trough were grass biomass, percentage of A. vesicaria individuals in flower, the percentage foliation of A. vesicaria and of the forage shrub Maireana sedifolia, and shrub forage biomass of A. vesicaria and M. sedifolia.

The rate at which these patterns were registered varied. After only 3 months, a piosphere pattern was evident for grass biomass. Marrubium vulgare, an introduced weed, invaded the trough site within the first 6 months. Almost no A. vesicaria shrubs had died after 2 years, but after 8 years there was a marked piosphere pattern in their mortality. The piosphere patterns in forage biomass and defoliation of A. vesicaria and M. sedifolia became more pronounced with time.

Some variables did not exhibit a piosphere pattern, such as the dimensions of the shrub R. ulicina and the densities of successive cohorts of the forb Erodium spp., even though there was an overall effect of grazing in reducing their values. There was no mortality of two dominant shrubs, M. sedifolia and R. ulicina, during the first 8 years.
Causes of nesting losses in the cattle egret Ardeola ibis in eastern Australia with special reference to the pathogenicity of the tick Argas (Persicargas) robertsi to nestlings
Authors: McKILLIGAN NEIL
Published: July 2006

In a 3 year study of the cattle egret at a heronry of 3500 nests in south‐east Queensland, 34% of eggs in 711 nests observed failed to survive to become fledglings (11 day old chicks). Fledgling mortality seemed much lower. The main sources of mortality were crow predation on eggs, failure of the incubated egg to develop fully, starvation of nestlings and tick infestation of nestlings. These were of about equal importance overall but their individual magnitudes varied considerably among the three seasons. The pattern of infestation of the cattle egret chick with the tick Argas (Persicargas) robertsi and the effect of this on chick health are described. An account is given of the other sources of morbidity also. The heronry appeared to be producing a net surplus of young despite these losses.
Gregarious flowering in a lowland tropical rainforest: A possible response to disturbance by Cyclone Winifred
Authors: HOPKINS MIKE S. , GRAHAM ANDREW W.
Published: July 2006

Observations in tropical lowland rainforests damaged by Cyclone Winifred on 1 February 1986 suggest that the disturbance has been followed by an unusual burst of flowering. Fifty‐four species of concurrently flowering shrubs and trees were recorded in early March along a 4 km road transect in a cyclone‐damaged forest. Approximately 80% of the smaller tree and shrub species observed were flowering. Twelve species which had flowered and fruited prior to the cyclone flowered again. Some species which normally flower following periods of partial or complete deciduousness in the drier months of the year flowered after being defoliated by the cyclone. Widespread defoliation of the rainforests, together with the hot, dry weather which followed the cyclone, exposed the understorey layers to abrupt increases in temperature, insolation, and water stress. It is postulated that these environmental changes may have effected the synchronization of flowering of a larger number of species than would normally occur. It is suggested that longterm changes in the species composition of the damaged forests as a result of coincidences of seed availability and regenerative space may occur.
Litter decomposition, soil respiration and soil chemical and biochemical properties at three contrasting sites in karri (Eucalyptus diversicolorF. Muell.) forests of south‐western Australia
Authors: O'CONNELL A. M.
Published: July 2006

Litter decomposition, soil respiration and soil chemical and biochemical properties were examined at three contrasting sites in karri(Eucalyptus diversicolorF. Muell.) forest of south‐western Australia. The study sites were: a recently clearfelled area (site CF2) which had been subjected to a slash regeneration burn following clearing; a pole‐stand regrowth forest about 40 years old which had been regularly burnt by cool, prescribed fires (site RB40); and a pole‐stand regrowth forest about 40 years old which had remained unburnt for many years (site UB40).

Leaf litter of uniform composition lost 40–54% of its original dry weight after decomposing for 82 weeks on the forest floor. A composite exponential model, with separate decay functions for labile and more resistant litter components, described rate of weight loss better than a simple exponential decay model. Labile components of litter were released at similar rates at the three sites. Decomposition of resistant litter components was slower (half‐life = 271 weeks) at the recently clearfelled site than at the two pole‐stand sites (half‐lives = 119 and 149 weeks). The order in which nutrients were released from decomposing litter, Na > Cl > K > Mg > S > Ca > N > P, was similar at each site. The rate of release of the more mobile elements Na, Cl, K, Mg and S, was also similar at each site. Changes in the amounts of Ca, N and P in decomposing litter differed between the three sites and the differences were related to the amounts of these nutrients in surface soil at each site.

Annual soil respiration decreased in the order site CF2 = site UB40 > site RB40. Seasonal variation in respired CO2was partly explained by variation in soil moisture and temperature. Soil carbohydrase activity at the recently clearfelled site was significantly lower than at the two well vegetated pole‐stand sites. The differences between sites in enzyme activities were related to differences in the amounts of organic C in surface soils of the three sites.

The amount of organic C in surface soil (0–15 cm) was 25–36% lower at the recently clearfelled site than at the two well vegetated pole‐Stand sites. Site disturbance during clearing, and combustion of soil organic matter by the subsequent slash regeneration burn, probably account for part of this difference. However, reduced inputs of organic matter in litterfall, slower rates of surface litter breakdown and increased rates of microbial mineralization of soil organic matter on recently clearfelled areas may also contribute substantially to depletion of soil organic C.
Subtidal macroalgal communities in the D'Entrecasteaux Channel, Tasmania
Authors: SANDERSON J.C. , THOMAS D. P.
Published: July 2006

Community descriptions and distributions of the dominant subtidal macroalgae were recorded for the D'Entrecasteaux Channel, Tasmania. These were related to the major environmental parameters of light, water movement, substrate and depth.

Six communities were recognized subjectively: (1) Durvillaea, (2) Phyllospora, (3) Macrocystis, (4) Ecklonia, (5) Fucoid and (6) Seagrass‐Cauterpa. These divisions were supported by cluster analysis of data from Tinderbox, a site at the northern end of the Channel.

Detrended correspondence analysis of community data suggested that light was the principal factor (Axis 1), followed by water movement, in determining species distributions at Tinderbox.

The algal communities determined are consistent with the generalized scheme proposed by Edgar (1984) for this area and are indicative of cold temperate waters and the Maugean subprovince.
Tasmanian high altitude grassy vegetation: its distribution, community composition and conservation status
Authors: KIRKPATRICK J. B. , DUNCAN F.
Published: July 2006

Grassy woodland, grassy shrubland, grassy sedgeland, tussock grassland and grassland are extensive on basalt, limestone and fine‐textured Quaternary deposits, are occasional on dolerite, granite and fine‐grained sedimentary rocks, but are absent from the siliceous mountains of Tasmania. With the exception of limestone lithosols, the grassy communities are confined to relatively deep soils with a low surface rock cover. Much of the area of the grassy communities below the climatic treeline has clearly been forest in the recent past, although some of the higher subalpine plains seem likely to have been grassy at least since the peak of the Last Glacial. The first axis of an ordination of floristic data from 190 quadrats had at one extreme the grassy communities which most resembled in their species composition the sedgelands and sclerophyll shrub woodlands of the west of Tasmania, and at the other extreme the grassy woodlands on relatively fertile, well drained sites in the centre and east of Tasmania. The second axis was correlated with altitude, probably inversely reflecting the growing season. The third axis was related most closely to a soil drainage index. Many of the 15 communities recognized from a polythetic divisive classification of the quadrats have highly local distributions. Six of the communities are totally unreserved and four are poorly reserved. An iterative method is used to develop a minimum reservation strategy involving seven areas.
The occurrence and diet of fishes in a tidal inlet to a saltmarsh in southern Moreton Bay, Queensland
Authors: MORTON R. M. , POLLOCK B. R. , BEUMER J. P.
Published: July 2006

The fishes occurring in the main tidal inlet to a typical saltmarsh situated in southern Moreton Bay were studied from January to December 1984. The aim of the study was to determine the type of fishes and their feeding habits within the inlet, particularly for species of economic importance. Sampling was conducted at night on the full and new moon phases, and during the day on the full moon phase. A total of 19 species were recorded from the inlet, of which 11 are of economic importance. Six species were considered common. Most fish which entered the inlet were juveniles. The diversity of the fish assemblage from the inlet was low when compared with findings of other studies conducted in Australian subtidal mangrove areas. Diel differences in the sire offish entering the inlet were recorded for several species. Two mark‐recapture programmes were conducted to investigate short‐term utilization of the saltmarsh by fishes. Recapture rates indicated that individuals of some species regularly utilized the saltmarsh. The most abundant species from the inlet were predominantly benthic feeders although one species fed on plankton. Terrestrial foods formed an important part of the diet of some fishes. The inlet serves as a feeding area for certain species although it is unlikely that these species rely exclusively upon the area. Future management of saltmarsh areas should include protection and maintenance of tidal inlets wherever possible.
The ecology of Salmonella serotypes in a wild marsupial (the quokka Setonix brachyurus) in a disturbed environment
Authors: HART R. P. , IVESON J. B. , BRADSHAW S. D.
Published: July 2006

Previous studies have shown that the quokka (Setonix brachyurus: Marsupialia) experiences a very extensive proliferation of Salmonella infections on Rottnest Is. (Western Australia) in association with seasonal starvation in a disturbed environment. The study reported here examined the distribution of the serotypes involved, the interaction of Salmonella with other hosts, and the resulting environmental contamination. In the quokka, the serotypes were found to be significantly non‐random in their distribution between areas (regardless of a seasonal cycle of infection rate in some areas) and between seasons. No one serotype showed a particular affinity for the quokka in the most adverse season. Study of the largest deviations showed that they could have been due to local amplification of particular serotypes in other hosts. It was not generally possible to distinguish the native and exotic serotypes as groups, and each serotype needed to be studied in terms of its own ecology. Environmental contamination is extensive due to proliferation of Salmonella in quokkas, but the interactions with other hosts were found to be important in determining the local distribution of serotypes. The results of this study are discussed in terms of the significance of the distribution of Salmonella in natural and disturbed areas in Western Australia, and of management of the problems created by proliferation of Salmonella in the Rottnest Is. quokka.
Effects of salinity and waterlogging on the vegetation of Lake Toolibin, Western Australia
Authors: FROEND RAYMOND H. , HEDDLE ELIZABETH M. , BELL DAVID T. , McCOMB ARTHUR J.
Published: July 2006

Increased rates of tree senescence and mortality in and adjacent to an ephemeral lake in the Western Australian wheatbelt have been attributed to increased levels of soil salinity and inundation following agricultural clearing. Winter lake salinities approximate freshwater lake values, but during periods when the lake is dry, capillary rise of groundwater is thought to increase surface soil salinity.

An undescribed species of Melaleuca and Casuarina obesa dominated the seasonally inundated regions of the lake bed. Aeolian deposits of higher elevation were dominated by Eucalyptus loxophleba, Allocasuarina huegeliana or species of Banksia. Woodland of E. oleosa var. longicornis and E. salmonophloia occurred predominantly on upland fluviatile deposits of sand and sandy clays.

Measurements of soil salinity and the calculation of percentage inundation from tree elevations and observations of tree vigour and xylem pressure potential response indicated that tree deaths in Melaleuca sp. and C. obesa were due to increased levels of salinity. Deaths and low vigours in E. rudis were attributed to both increasing salinities and prolonged inundation. We believe control of ground water levels should be a major consideration in the preservation of this ephemeral lake and the water fowl populations it supports.
Spatial heterogeneity of post‐dispersal survivorship of Queensland rainforest seeds
Authors: WILLSON MARY F.
Published: July 2006

Short‐term seed survivorship for several species of the Queensland rainforest was compared in forests and early successional fields, treefall gaps and forest interior, and an array of microhabitats (tree buttresses, logs, forest floor with and without leaf litter cover). Seed survivorship was lower in forest than in field at one site, but equal at another. No differences were found in and out of treefall gaps, in contrast to several other studies. Microsites had little consistent influence on short‐term seed survivorship. A survey of the literature showed no consistent habitat or microhabitat patterns in seed survivorship.
Survivorship, growth and self‐thinning in Banksia ericifolia
Authors: MORRIS E. C. , MYERSCOUGH P. J.
Published: July 2006

High‐density (dense) and low‐density (sparse) plots were set up in naturally sown monospecific stands of Banksia ericifolia in coastal heath, 3 years after fire. This was done both in high‐growth and low‐growth areas. Plant mortality was recorded quarterly, and two harvests were made at 6 and 9 years to sample growth. Density‐independent mortality at an exponential rate was observed in the low‐growth treatments at both densities, and in the high‐growth sparse treatment. Growth level affected mortality, with the half‐life of populations in the high‐growth sparse plots being double that of populations in the low‐growth plots. Density‐dependent mortality (self‐thinning) was seen only in the high‐growth dense plots. Seasonal effects on mortality were slight; maximum mortality was observed in the spring‐summer period in plots subject to density‐independent mortality, and in the winter‐spring quarter in plots that had self‐thinned. Yields in the high‐growth plots and the low‐growth dense plots were high for heath vegetation. The self‐thinning populations did not exceed White's (1985) upper boundary for thinning lines of log intercept (K) = 5 on standardized axes. The data suggested a log intercept value in the range 4.8–4.9 in the high‐growth stands assuming a thinning‐line slope of – 1.5. Banksia ericifolia (a large shrub/small tree) has a high mean plant weight per given thinning density compared with trees, where an upper limit of log K= .4 has been suggested by White (1985). The volume of canopy space per plant in B. ericifolia is not unusual compared with other species. The amount of biomass packed into a given volume of canopy space was high in this Banksia, achieved by having leaves with a low ratio of area to weight (specific leaf area, SLA). For given values of density, leaf area index and proportion of shoot as leaf, plants with a low SLA will be several times heavier than plants with a high SLA. This achieves a high biomass to volume ratio without an erectophile canopy and may explain the high intercept seen for thinning lines of conifers.
Factors determining seed persistence of Chondrilla juncea L. (skeleton weed) in southern Western Australia
Authors: PANETTA F. D.
Published: July 2006

Except when sown into non‐wetting soils, buried seeds (achenes) of Chondrilla juncea germinated readily following summer rainfall events of less than 10 mm. Seeds lying on the surface were much less likely to germinate in response to small rainfall events, but were prone to predation by seed‐harvesting ants. Although seedlings were capable of resuming growth following temporary dehydration at the earliest stages of emergence from the pericarp, very few of these were able to establish. Establishment from summer germination was virtually nil.

The capacity to germinate at higher temperatures was increased following storage for seeds which had been produced in February and March. However, this was considered to be only a weak expression of a release from relative dormancy, compared to the marked changes in temperature response which occur during the after‐ripening of many winter annuals. Differences in the germination behaviour and persistence of seeds of the narrow‐leafed and broad‐leafed forms of C. juncea, when evident, were usually slight.

On the basis of an analysis of climatic records for 13 wheatbelt sites, obtained over the period for which C. juncea has been known to occur in Western Australia, it is argued that more than two germinating events could be expected to occur, on average, during the summer months. The relative absence of mechanisms which might confer protection from the effects of unseasonal rainfall, in conjunction with evidence for high levels of seed predation, point to considerable seed losses. Thus the abundance of the species elsewhere in Australia appears to have resulted from its capacity for vegetative regeneration.
Early Holocene population expansion of some rainforest trees at Lake Barrine basin, Queensland
Authors: CHEN YINSHUO
Published: July 2006

Pollen influx data derived from a sediment core from a small crater lake were related to two population growth models. Doubling times for some tropical rainforest tree taxa, estimated from the models, are 63–165 years for angiosperms and 199–355 years for conifers. These values are generally higher than those for temperate forest trees in the Northern Hemisphere. The results show that fossil pollen data can provide useful information on tree population ecology in tropical areas.
The impact of predation by the powerful owl, Ninox strenua, on a population of the greater glider, Petauroides volans
Authors: KAVANAGH RODNEY P.
Published: July 2006

Powerful owls were frequently observed during a study of the ecology of a community of arboreal marsupials in south‐eastern New South Wales. For about 17 months the population of greater gliders in the 100 ha study area appeared to remain ‘stable’ at more than 80 individuals. In the following 46 months, the population declined to about one‐tenth of its previous level. The forest in the study area was unlogged and remained undisturbed during this period. The frequency of sightings of powerful owls holding captured greater gliders, and of observations on the ground of tails and bodies belonging to greater gliders, and the unaccountable disappearance of 9 out of 11 individually marked greater gliders in the study area, suggest that the observed decline in the population of greater gliders was due to predation by the powerful owl. Powerful owls were not detected in the study area during the first 12 months or the last 21 months of the study. It is suggested that powerful owls forage by concentrating their activities in pockets of their large home range until they reduce the populations of their preferred prey below limits where it becomes difficult to catch the remaining animals. If preferred prey are available elsewhere, powerful owls probably move their centres of foraging activity to these pockets and harvest them before moving on to the next pocket of their range.
Behavioural mechanisms of microhabitat selection and competition among three species of arid zone dasyurid marsupial
Authors: MOSS G. L. , CROFT D. B.
Published: July 2006

Behavioural mechanisms that may facilitate ground surface microhabitat separation of the Australian arid zone dasyurids, Sminthopsis crassicaudata, Planigale gilesi and P. tenuirostris, were investigated in a terrarium under conditions identical to summer and winter conditions. Controlled introduction and removal experiments showed that in the presence of S. crassicaudata on the ground surface, both P. gilesi and P. tenuirostris exhibit changes in their general behaviour along with an absence of surface activity and a significant decrease in the percentage of total time spent active. This is accompanied by an increase in the frequency of active bouts less than 30 s in duration and a decrease in the frequency of bouts of greater than 30 s duration. These results suggested avoidance of S. crassicaudata at the surface by the planigales, and that behavioural interference could be a mechanism maintaining the spatial and temporal use of microhabitat of these carnivorous species. This study supports much of the indirect evidence suggesting that interspecific competition is an important factor influencing the structure of dasyurid communities.
Yearly variation in seasonal patterns of honeyeater abundance, flower density and nectar production in heathland near Sydney
Authors: PYKE GRAHAM H.
Published: July 2006

Despite a consistent seasonal pattern of daily production of nectar‐energy per unit area with peak production around the end of May, the seasonal pattern of honeyeater abundance is not consistent between years and does not correspond to the pattern of nectar‐energy production.
The impact on native mammals of land‐use changes and exotic species in the Bega district, New South Wales, since settlement
Authors: LUNNEY DANIEL , LEARY TANYA
Published: July 2006

Historical records for the Bega district were examined to chart the environmental changes wrought by Europeans through habitat alteration and the introduction of exotic species, and to interpret the impact of these on native mammals. Early recorded increases in native mammal populations, particularly koalas, may have been attributable to a decline in Aboriginal hunting pressure. After settlement in 1830, the valley forest was cleared progressively, ecosystems were altered by grazing and improved pastures, and many introduced plants became weeds in the disturbed environment. The timber industry exploited the forests of the valley and then the slopes of the surrounding mountains. Three exotic mammal species had a major impact on the district — hares, rabbits and foxes. Of the native fauna, the large and medium sized mammal species were those recorded most frequently. Dramatic fluctuations in numbers occurred in most of these species, and many reached plague proportions between 1880 and 1910, after which their numbers fell sharply. The peaks of exotic mammals and the decline of native mammals coincided with the clearing of the remaining forests in the Bega Valley. Many native mammal species are now rare, four are in danger of extinction, and at least six species have become locally extinct since settlement. As most of the native mammal populations in the district now occur in the State Forests surrounding the Bega Valley, the importance of preserving or managing these forests for wildlife must be weighed against proposals to manage the forests for pulpwood (woodchip) production.
Spatial patterning of sweet briar(Rosa rubiginosa)by two vertebrate species
Authors: HATTON THOMAS J.
Published: July 2006

The dispersal and spatial patterning of sweet briar(Rosa rubiginosa)by pied currawongs(Strepera graculina)and horses(Equus caballus)on the southern tablelands of New South Wales was investigated. These two vertebrate species eat the sweet briar fruits and disperse them in a viable condition. The spatial patterns of horse faeces and pied currawong pellets were shown to correspond to the patterns of sweet briar in paddocks which had one of these vertebrate species present. Paddocks with a history of horse grazing but with no large roosting trees had sweet briar populations which were distributed almost randomly; in paddocks never grazed by horses but with roosting trees there was a strong aggregation of sweet briar under trees. These spatial patterns were additive in paddocks with a history of both horse grazing and large trees. Such structuring of vegetation by vertebrates is discussed as an alternative hypothesis to be considered when interpreting ecological processes from spatial patterns.
Colonization of experimentally disturbed patches by stream macroinvertebrates in the Acheron River, Victoria
Authors: DOEG T. J. , LAKE P. S. , MARCHANT R.
Published: July 2006

Twenty‐five patches (1 m2) of natural stream substratum in the Acheron River, Victoria, were physically disturbed by kicking and raking during winter 1986 and summer 1987. The macroinvertebrate composition of these disturbed patches was examined at various times over the following 71 days, and compared with adjacent undisturbed control patches sampled concurrently.

The disturbance did not alter the particle‐size distribution (> 150 μm) of the disturbed patches. Organic material was reduced in the disturbed patches by about 70% in each season, but returned to control levels within 21 days in winter and 8 days in summer.

The total number of species, and the density of species and individuals were all significantly reduced by the disturbance. Recovery of species density was complete after 21 days during winter and 8 days during summer, and the density of individuals recovered after 71 days during winter and 8 days during summer. The differences were due to the slower colonization rate of Chironomidae in winter, either because of a lower drift rate, or a slower recovery of detritus in winter.

Individual species showed variations in colonization patterns, most increasing steadily at various rates, with some declining after an initial rapid increase (e.g. Baetis pp.). In the latter case, the density changes were mirrored in the control patches, emphasizing the need to take control samples concurrently with experimental samples.

In each season, the species remaining immediately following the disturbance, and those subsequently colonizing the disturbed patches were in the same rank order (Spearman Rank correlation) as their occurrence in the control patches, suggesting that no taxa were differentially affected by the treatment.

No evidence was found to allow the application of the Intermediate Disturbance Hypothesis to explain species diversity at the scale of this study. It appears that current hypotheses developed to explain the relationship between diversity and disturbance in sessile communities do not apply to highly mobile communities in streams.
Post‐dispersal seed predation of an exotic weed, Mimosa pigra L., in the Northern Territory
Authors: WILSON C. G.
Published: July 2006

The removal of seeds of the exotic shrub Mimosa pigra from the ground beneath a thicket of the plant and from the open floodplain surrounding the thicket was studied experimentally. Seeds placed beneath the canopy of the M. pigra thicket were taken predominantly by vertebrates (probably omnivorous rodents) while those on the open floodplain were taken predominantly by ants. After 14 days exposure with no barriers to seed removal, less than half of the seeds placed in either habitat had disappeared. Of the seeds that were removed, over 75% had disappeared from both habitats within 5 days. It is unlikely that post‐dispersal seed predation appreciably inhibits the spread or maintenance of stands of this weed in tropical Australia.
Predation by Australian magpies (Gymnorhina tibicen) on pasture invertebrates: Are non‐territorial birds less successful?
Authors: VELTMAN CLARE J. , HICKSON ROBERT E.
Published: July 2006

Diet composition and prey intake rates of Australian magpies in a New Zealand population were investigated to determine whether flocking, non‐territorial birds were less successful predators of pasture invertebrates than territorial birds. Time‐activity budgets showed that flock magpies foraged throughout the day during February and March, indicative of a prey shortage at that time. Prey abundance was therefore measured in the autumn months but there was no evidence of a large quantitative difference in the food supply of flock and territorial magpies. Significantly fewer invertebrates were collected from pitfall traps in the flock foraging area, but these were counterbalanced by significantly more scarab beetle larvae and more flying insects, obtained by sweep‐netting. When compared with territorial magpies, flock birds exhibited similar peck rates, prey intake rates, and earthworm intake rates. While there were qualitative differences in the diets of flock and territorial magpies, determined by faecal analysis, five of seven prey items analysed were captured in the same relative proportions by the flock and territorial birds. Earthworms exceeded their relative availability in the diets of flock birds, and more scarab larvae were found in the diets of territorial magpies. Non‐territorial magpies were therefore no less successful than territorial birds during the autumn, and it is suggested that the function of flocking behaviour may eventually be discovered through consideration of why non‐territorial birds never occur as solitary individuals, rather than emphasizing comparisons with territorial magpies.