bluuebunny/crossref_metadata_2025 huggingface dataset:
Photosynthetic and growth responses to different light regimes of the major canopy species of Tasmanian cool temperate rainforest
Authors: READ J.
Published: July 2006

Seedlings of the cool temperate rainforest tree species, Nothofagus cunninghamii, Atherosperma moschatum, Eucryphia lucida, Phyllocladus aspleniifolius, Lagarostrobos franklinii and Athrotaxis selaginoides, were grown in various light regimes and their instantaneous lightdependence curves and relative growth rates were measured. A. moschatum had the highest relative growth rate of all species in heavy shade, and its light‐dependence curves were also characteristic of a relatively shade‐tolerant species. A. selaginoides and L. franklinii seedlings raised in heavy shade had low instantaneous light compensation points but their growth rates were not distinct from that of N. cunninghamii. The maximum relative growth rate of the gymnosperms was low due to a low specific leaf area and leaf area ratio, although the maximum rates of photosynthesis on a leaf area basis were similar to N. cunninghamii and E. lucida. The low leaf area ratio and specific leaf area affected both the relative growth rate and the growth light compensation point. Although in the heaviest shade treatment there was no difference in growth rate between N. cunninghamii, E. lucida, L. franklinii and A. selaginoides, in moderate shade treatments N. cunninghamii had a higher relative growth rate than the gymnosperms and a higher maximum rate of photosynthesis on a leaf dry weight basis than all species when raised in semi‐shaded natural light conditions. These species commonly occur in mixture in Tasmanian cool temperate rainforest and these results are discussed in terms of forest dynamics.
Rates of seed removal by ants at heath and woodland sites in southeastern Australia
Authors: ANDERSEN ALAN N. , ASHTON DAVID H.
Published: July 2006

Ants often appear to be important post‐dispersal seed predators, particularly in Australia where they are exceptionally abundant and apparently can remove large quantities of seeds from the ground. Rates of seed removal by ants usually are measured by recording removal from artificial seed baits, but the reliability of this approach has not been tested, nor have there been many attempts to integrate the results with the activity of seed‐eating ants. This paper describes the rates of seed removal, estimated using a baiting technique that is tested for its reliability, by the seed‐eating ants in adjacent heath and woodland sites at Wilson's Promontory, Victoria. Ants removed up to 100% of seeds, but rates varied according to seed species, size of seed clumps, season, time of exposure, and other aspects of the baiting technique. Methodological guidelines are provided to make baiting conditions approximately those likely to occur in nature.

Seed‐eating ants, particularly species ofRhytidoponera, Chelaner and Pheidole, were by far the most important post‐dispersal seed predators, and patterns of seed removal were directly related to their composition, abundance and foraging behaviour. Lygaeid bugs were also observed eating seeds, but there was no evidence of seed predation by rodents or birds.

The results suggest that seed predation by ants can substantially deplete seed reserves: however, its actual effect on seedling recruitment is likely to depend on many factors including seed size, crop size, weather, timing and location of seed fall, availability of alternative food sources, patterns of seedling mortality, and fire, none of which have been adequately investigated.
Foraging patterns of breeding birds in eucalypt forest and woodland of southeastern Australia
Authors: RECHER H. F. , HOLMES R. T. , SCHULZ M. , SHIELDS J. , KAVANAGH R.
Published: July 2006

The foraging ecology of eucalypt forest and woodland birds was studied on three 10 ha plots in southeastern Australia. Quantitative data were obtained for 41 species of which 31 were insectivorous, eight were nectar‐feeders, and two were parrots that fed primarily on eucalypt seeds. Birds‐of‐prey, large omnivores and frugivores were uncommon. Insectivorous birds differed in foraging behaviour, the substrates on which they found prey, and foraging height. Nectar‐ feeders exploited a variety of carbohydrates including nectar, honeydew, lerp, manna and sap. Nectarivorous birds were separated by foraging behaviour, substrate, height and by the extent to which they used the different types of carbohydrates. Carbohydrates were also an important food resource for some insectivores. By understanding how birds exploit food resources within forest and woodland environments, the features of the environment which need to be conserved or manipulated to manage forest avifaunas can be identified. For example, in addition to the substrates such as foliage and bark, usually associated with the foraging of forest birds, carbohydrates and loose bark were identified as important resources for birds in eucalypt forests and woodlands. The broad importance of these two resources to the avifauna had not been previously appreciated, yet both may be sensitive to environmental changes associated with logging and other forest management practices which alter the composition or age‐class structure of forests.
Collembolan associations in natural versus improved pastures of the New England Tableland, NSW: Distribution of native and introduced species
Authors: KING KATHLEEN L. , GREENSLADE PENELOPE , HUTCHINSON K. J.
Published: July 2006

Native Australian species of Collembola dominated natural pasture in numbers of species present and in abundance, while introduced Collembola dominated fertilized pasture sown to exotic species. Those collembolan species which were restricted to one pasture type only were mainly epigeal and hemiedaphic species of the herbage and litter. Increased grazing by sheep decreased species richness and increased uniformity of Collembola in both pasture types. The abundance of introduced Collembola was positively associated with phosphorus content of litter.
Recovery of some surface soil properties of ecological interest after sheep grazing in a semi‐arid woodland
Authors: BRAUNACK M. V. , WALKER J.
Published: July 2006

Solodic soils within a semi‐arid poplar box (Eucalyptus populnea) woodland at Wycanna, in southern Queensland, have been subjected to impacts from sheep and cattle grazing for at least 100 years. The micromorphology of the surface of two soils, a gradational texture profile (Gn 3.13, Paleustalf) and a duplex profile (Db 1.23, Paleustalf) showed that compaction had occurred. Recovery of the soil surfaces following removal of animal grazing was measured in terms of porosity, presence of illuvial layers, surface soil strength, some chemical properties and water infiltration rates. The grazing impact was greatest on the Gn 3.13 soil and visual signs of the grazing impact were still evident 16 years following sheep removal. Reduced soil organic matter and increased surface soil hardness as a result of grazing, rather than surface crusting or changes in water infiltration rates are suggested as the mechanisms controlling the observed increases in woody plant populations in these semi‐arid woodlands.
Niche compression: Two tests of an hypothesis using narrowly sympatric predator species
Authors: DICKMAN C. R.
Published: July 2006

The compression hypothesis predicts that when two species occur together in narrow sympatry, individuals in the overlap zone will use a smaller range of habitats and a larger or unchanged range of prey than individuals in allopatry. This report attempts to validate the assumptions underlying this hypothesis, and describes two tests of the predicted resource shifts using narrowly sympatric species of predatory marsupials (Antechinus spp.). In the first test, using A. stuartii and A. flavipes, there was little correspondence between observed and predicted changes in diet and habitat use (as measured by indices of niche breadth) for populations of either species. One index of niche breadth (Levins' B) revealed no trends in resource use, but a proportional similarity index relating resource use to resource abundance consistently indicated that the niche breadths of each species were greater in allopatry than in narrow sympatry. In the second test, using A. stuartii where it occurred alone and in narrow sympatry with A. swainsonii, there was again little correspondence between observed and predicted changes in resource use for seasonal or overall data. Differences in magnitudes of niche breadths between allopatric and narrowly sympatric A. stuartii were smaller in this test than in the first.

While these findings provided no support for the compression hypothesis, they suggested three situations in which the predictions of the hypothesis may generally not apply. These are:

when the predators are active, dietary generalists (diet cannot expand in sympatry);

when one species is a markedly superior competitor to the other (the dominant species suffers little or no niche compression in sympatry); and

when the species compete by interference rather than exploitation (one species is evicted from sympatry or both show compression in habitat use and diet).
Herbage response to tree thinning in a Eucalyptus crebra woodland
Authors: WALKER J. , ROBERTSON J. A. , PENRIDGE L. K. , SHARPE P. J. H.
Published: July 2006

The effects of a range of tree densities on native herbage (mainly Aristida ramosa, Bothriochloa decipiens and Themeda australis biomass in a Eucalyptus crebra woodland near Kingaroy, Queensland, were investigated between March 1977 and July 1981. Rainfall in this area averages 750 mm year−1. Initial tree density was 640 trees ha−1 and this was manipulated using arboricide chemicals to leave plots containing 640, 320, 160, 80 and nil live trees ha−1. Fires were excluded from the whole area, and half the plots were grazed by cattle. The largest increase in herbage biomass was recorded in the ‘all trees killed’ treatment (nil trees ha−1), closely followed by the ‘scattered tree’ treatment (80 trees ha−1). The relationship between tree density and herbage biomass was linear. Recruitment of grass and forb plants, as reflected by changes in density, varied according to treatment. Increased grass recruitment was correlated with cattle grazing, whilst forb recruitment was influenced mainly by tree density.
Surface soil chemical and physical patterns in a brigalow–Dawson gum forest, central Queensland
Authors: DOWLING A.J. , WEBB A. A. , SCANLAN J. C.
Published: July 2006

Brigalow (Acacia harpophylla)–Dawson gum (Eucalyptus cambageana) open forests are predominantly supported by solodic soils in central Queensland. This report describes relations between some physical, chemical and morphological properties of surface soils (0–0.10 m) within a virgin brigalow–Dawson gum forest. Soil property gradients were found to radiate horizontally from tree‐dominated to non‐vegetated areas, indicative of a vegetation‐induction process. These reflect the importance of litterfall organic matter in determining soil fertility and soil physical conditions at this site.

The decomposition of litterfall is probably responsible for significant increases in soil organic carbon (C), total nitrogen (N) and total sulphur (S) concentrations with increasing vegetation canopy cover. The composition of soil organic matter appears constant across the study area, as similar soil C:N:S ratios were recorded across all vegetation canopy classes. Soil salinity, total phosphorus, mineral nitrogen, cation exchange capacity, exchangeable calcium and exchangeable potassium levels also increased with increasing vegetation canopy cover.

Surface soil physical properties were also related to vegetation canopy cover. Bulk density and the < 20 μm dispersion ratio decreased while soil micro‐relief and A hor̀izon depth increased with increasing vegetation canopy cover. Organic C, through inverse relations with bulk density and the < 20 μm dispersion ratio, appears to enhance soil porosity and aggregate stability, indicating the role of organic matter in the stabilization of larger virgin soil aggregates.

The close association between virgin forest and surface soil fertility is seen to have implications for changes in land‐use, with a decline in nutrient availability, soil aggregate stability and productivity following forest clearing.
Impact of flower and seed predators on seed‐set in two Banksia shrubs
Authors: ZAMMIT CHARLES , HOOD CHRISTOPHER W.
Published: July 2006

A non‐systemic Insecticide was used to exclude flower and seed predators from Banksia ericifolia and B. oblongifolia Inflorescenses. In B. ericifolia this treatment doubled the number of inflorescences that set seeds, and increased by 40% the number of seeds produced per Inflorescence. Insecticide treatment did not alter either of these components of seed‐set in B. oblongifolia partly because the experiment began too late to exclude flower predators In this species. The results obtained for B. ericifolia support the hypothesis that flower and seed predators explain, in part, the low incidence of seed‐bearing cones and the low seed:flower ratios reported for many Banksia species.

Each Banksia species supports two guilds of Inflorescence predators. Two Lepidopteran species feed on young flowers; one of these causes tunnel damage to the rachis. Each Banksia species also supports five Lepidopteran and two Curcullonid seed‐predators. About 40% of these herbivorous Insects are common to both shrubs.
Intersexual niche segregation among three bark‐foraging birds of eucalypt forests
Authors: NOSKE R. A.
Published: July 2006

All three species of specialized bark‐climbing birds in eucalypt forests of north‐eastern New South Wales exhibited sexual differences in their foraging behaviour. The degree of these differences was weakest in the least social species and strongest in the most social species, suggesting that intersexual niche segregation is an adaptation to reduce intraspecific competition for food. In the least social White‐throated Treecreeper, the slightly longer‐billed males foraged on dead branches more than females only during the breeding season when pair members were forced to share the same area. In the group‐living Red‐browed Treecreeper and Varied Sittella, males foraged lower and used rough‐barked trunks and limbs more than females throughout the year. Sexual differences in the foraging substrates of Sittellas may have been related to sexual dimorphism of the bill, but in the monomorphic Red‐browed Tree‐creeper, male dominance was probably important. Some evidence suggests that further subdivision of the niche may occur in the highly social Sittella along the vertical dimension according to age and/or reproductive status. This report argues that intersexual niche segregation is just as likely to develop under conditions of increased interspecific competition as under reduced competition.
Distribution of the immature stages of Aedes vigilax on a coastal salt‐marsh in south‐east Queensland
Authors: DALE P. E. R. , HULSMAN K. , HARRISON D. , CONGDON B.
Published: July 2006

The distribution of eggs and larvae of Aedes vigilax was studied on part of a coastal salt‐marsh in south‐east Queensland. At the macro‐scale (8 ha area), the largest numbers of larvae hatched were from samples taken in areas with relatively low open vegetation adjacent to drainage channels. Such areas are likely to be suitable for egg conditioning and hatching and are also accessible to adult mosquitoes. At the micro‐scale (the environs of two small pools), most hatching occurred in narrow bands at specific elevations from the pool bottom but the relationship with vegetation was variable. Failure to hatch larvae from samples taken at the start of, or during, the cooler months was thought to be associated with egg diapause. At the macro‐scale whilst the marsh was flooded, most larvae were found in two habitat types: the tall dense Sporobolus virginicus in relatively elevated locations and in depressions dominated by Sarcocornia quinqueflora. At the meso‐scale (on a 1.4 ha grid) the distribution of larvae was found to be further related to water movement. Most larvae were in areas of slower water movement and appeared also to be redistributed by tides.
Seasonal changes in the abundance and body condition of honeyeaters (Meliphagidae) in response to inflorescence and nectar availability in the New England National Park, New South Wales
Authors: McFARLAND DAVID C.
Published: July 2006

Seasonal changes in numbers and body condition of honeyeaters were examined over 2 years in the New England National Park, New South Wales, Australia. Nectar availability measured as inflorescence density and nectar production were also recorded. In the main study site, the abundance of six of the seven most common species of honeyeater was significantly correlated with inflorescence density. However, honeyeater numbers were not significantly correlated with daily energy productivity. Unlike most honeyeater communities, the New England community was dominated numerically by the Eastern Spinebill, the smallest of the most common species present. Among the most common species, the duration of time a species was recorded in the area was negatively, but not significantly, correlated with its size. All species examined showed similar seasonal changes in body condition, with the highest bodyweights and fat deposits recorded in winter.
Population dynamics of the shrub Acacia suaveolens (Sm.) Willd.: Fire and the transition to seedlings
Authors: AULD TONY D.
Published: July 2006

Fire, through soil heating effects, causes flushes of seed germination in Acacia suaveolens. Optimal temperatures for germination are between 60 and 80°C for any duration, or up to 100°C for durations less than 1 h. Exposure to temperatures less than 60°C leaves seeds dormant and viable, whilst seed death occurs in increasing proportions with increasing exposure to temperatures greater than 80°C.

A field study of temperatures in the soil under simulated burns showed that the innate seed dormancy in A. suaveolens would only be broken for seeds up to a depth of 1 cm in ‘cool’ or 4 cm in ‘hot’ burns. In the hot burns some of the seeds in the top 1 cm of the soil were killed by excessive heating. These simulated burns most resemble cool and moderate/high intensity wildfires, respectively. Seeds can emerge from depths up to 8 cm and, for any seeds buried deeper than this, the probability of emergence is progressively reduced down to nil at 14 cm. Seeds buried between 5 and 10 cm will be heated sufficiently to break their dormancy only in a very high intensity wildfire. Seeds buried between 5 and 10 cm deep mostly occur in nests of an ant, Pheidole sp.

Field observations of emergent seedlings confirm that post‐fire emergence is concentrated over a small range of soil depths directly related to the intensity and duration of heating that occurs, whilst occasional seedlings may appear from greater or lesser depths largely dependent upon the spatial heterogeneity of soil heating in natural fires.
Stemflow as a nutrient source for nikau palm (Rhopalostylis sapida) in a New Zealand forest
Authors: ENRIGHT N. J.
Published: July 2006

The hypothesis that stemflow is important in contributing to the nutrient requirements of nikau palm Rhopalostylis sapida individuals is examined. Stemflow directs many times more sodium, potassium, calcium and magnesium to the base of the palm than is required for annual net production. There are three sources for nutrients found in stemflow: (1) atmospheric inputs (wet and dry deposition); (2) foliar leaching; and (3) alien litter leaching and decomposition. Sources I and 3 together, representing nutrient input, contribute substantially more nutrients than are required for net annual production in mature individuals.
Densities of Collembola and Acarina in the soil and litter of three indigenous South Australian forests related to layer, site and seasonal differences
Authors: HUTSON BARRY R. , VEITCH L. G.
Published: July 2006

A quantitative study was made of the micro‐arthropod fauna in the litter and two soil layers at three South Australian forest sites (designated ‘dry’ medium’ and ‘wet’) using data taken at monthly intervals over 2 years. This study examined variations in density estimates of the major taxonomic groups of Acarina and Collembola that were associated with sample depth, site and season.

There were substantial differences in the proportions of variation attributed to layer, site and seasonal effects. Most variation was associated with layer differences, being greatest in the acarine Prostigmata and in the collembolan Onychiuridae. Only the acarine Astigmata had slightly more variation between sites than between layers.

Seasonal variation exceeded site variation in all collembolan groups except the Entomobryidae. In the acarine groups estimated ratios of seasonal to site variation were 6.1, 1.6, 1.0 and 0.4 for the Mesostigmata, Prostigmata, Cryptostigmata and Astigmata, respectively.

Some variations due to inconsistencies in the above patterns were significant statistically but were small compared with variations associated with the seasonal, layer and site effects.

Densities of all animals had marked seasonal variation which was broadly similar to that of rainfall in the warm temperate, mediterranean type climate of the region. Minimum density and activity occurred in about the last week in January, a period of maximum temperature and low soil moisture content; maxima were usually about 7 months later. This contrasts with warm and cool temperate areas of Australia with summer rainfall, where peak densities have been recorded in summer.

The Mesostigmata, Astigmata, Podundae and Onychiuridae patterns of seasonal variation did not differ significantly with layer or site differences. The remaining groups had significant differences with layers and sites, the former being larger. Density minima and maxima were generally later going from litter to lower soil, about 2.5–8 weeks for density maxima and 0–4 weeks for minima. Groups with significant lags showed reduced amplitude in their seasonal variation with increased depth.

There was little seasonal variation in the relative proportions of all animal groups.
Effects of an epiphytic alga on abundances of fish and decapods associated with the seagrass Zostera capricorni
Authors: BELL JOHANN D. , WESTOBY MARK
Published: July 2006

During a field experiment to test effects of changes to leaf height and density of Zostera capricorni on associated fish and decapods, more than one‐third of the substratum at some sites was covered by the epiphytic brown alga Giffordia mitchelliae. This paper reports apparent effects of the alga on the 13 most abundant species of fish and decapods, and interactions between effects of the alga and those due to height and density of the seagrass leaves. Abundances of three species were significantly lower, and those of two species were significantly greater where the alga occurred. There were interactions between effects of the alga and those of leaf height and/or density for another four species. In all four cases, when the alga had an effect, it was to decrease abundance. The effects of Giffordia were generally opposite to those reported for drift algae in seagrass habitats elsewhere. The lower abundances of seven species where algal cover was great are best explained by an existing model for seagrass habitats that predicts reductions in abundance of individuals when the ratio of plant material to substratum is very high.
The biomass of New England peppermint (Eucalyptus nova‐anglica) in relation to insect damage associated with rural dieback
Authors: LOWMAN M. D. , BURGESS A. D. , HIGGINS W. D.
Published: July 2006

Two adjacent mature trees of New England peppermint (Eucalyptus nova‐anglica) were harvested with the aid of a cherry picker to determine their biomass distribution and insect damage. One suffered from obvious symptoms of rural dieback and the other was healthy. Weights of foliage and wood were measured, and insect damage for all leaves and branches was quantified. For each tree 25% of the roots were extracted from the soil using a bulldozer and manual methods; they were then weighed and damage by insects estimated. The healthy tree lost more leaf surface area to insects (11% or 1.1 kg vs 9.2% or 0.3 kg); but the dieback tree had four times more wood affected by boring insects (19% cf. 5%); and only 20% root biomass remaining (92 kg cf. 488 kg). The accuracy of sampling techniques needed to measure defoliation and the consequences of insect damage to dieback of rural eucalypts are discussed.
Analysis of the development of major plagues of the Australian plague locust Chortoicetes terminifera (Walker) using a simulation model
Authors: WRIGHT D. E.
Published: July 2006

The development and decline of all the past major plagues of Chortoicetes terminifera in Australia has been analysed using all available locust data and a simulation model to estimate the course of events for periods when few locusts were reported. The model is based on the developmental biology of the locust and includes methods of estimating the duration of egg, nymphal and adult development and uses a pasture growth index and potential night displacement index to assess likely survival and migration.

The analysis shows that five of the six plagues originated in the arid interior, where good spring and summer rain allowed two or three consecutive generations of successful breeding, before emigration to the agricultural country occurred in the late summer or early autumn. This is contrary to the idea held previously that most plagues developed from local breeding in established outbreak areas in the agricultural belt. The applications of these results, to improve population monitoring and control strategy by suggesting the best timing for surveys and when control would have most effect, are discussed.
Effect of disturbance and nutrient addition on native and introduced annuals in plant communities in the Western Australian wheatbelt
Authors: HOBBS R. J. , ATKINS L.
Published: July 2006

To investigate factors affecting the ability of introduced species to invade natural communities in the Western Australian wheatbelt, five communities were examined within a nature reserve near Kellerberrin. Transect studies indicated that introduced annuals were more abundant in woodland than in shrub communities, despite an input of introduced seed into all communities. The response of native and introduced annuals to soil disturbance and fertilizer addition was examined. Small areas were disturbed and/or provided with fertilizer prior to addition of seed of introduced annuals. In most communities, the introduced species used (Avena fatua and Ursinia anthemoides) established well only where the soil had been disturbed, but their growth was increased greatly when fertilizer was also added. Establishment and growth of other introduced species also increased where nutrient addition and soil disturbance were combined. Growth of several native annuals increased greatly with fertilizer addition, but showed little response to disturbance. Fertilizer addition also significantly increased the number of native species present in most communities. This indicates that growth of both native and introduced species is limited by nutrient availability in these communities, but also that introduced species respond more to a combination of nutrient addition and soil disturbance.
Predation creates haloes of bare space among prey on rocky seashores in New South Wales
Authors: FAIRWEATHER PETER G.
Published: July 2006

Field observations on rocky shores in New South Wales suggested a link between pools or wet crevices, predatory whelks foraging from them, and areas around the crevices that were mostly bare of prey (‘haloes’). Whelks were most common in and around crevices but ventured out to feed. Previous work had shown that foraging excursions were cyclical over time. The community of prey also changed with distance from crevices, most types of prey being more abundant further away. A field experiment showed this pattern to be at least partly due to the crevice‐bound foraging of the whelks. Experimental removal of whelks over 2 years at several sites caused the gradients in the abundance of prey with distance from crevices to disappear, whilst these patterns persisted and even grew more intense in adjacent control areas. This combination of biotic and physical processes (predation, desiccation, foraging behaviour) is discussed as an important influence on spatial patterning in this and other communities.
The effects of rabbit grazing on regeneration of sheoaks, Allocasuarina verticilliata and saltwater ti‐trees, Melaleuca halmaturorum, in the Coorong National Park, South Australia
Authors: COOKE B. D.
Published: July 2006

Sheoaks and saltwater ti‐trees regenerate poorly within the Coorong National Park unless they are protected from grazing mammals. The age structure of these tree populations suggests that both species regenerated vigorously in the 1950s when myxomatosis kept rabbit numbers low. Experiments demonstrated that unprotected seedlings are quickly found and eaten by rabbits, particularly if alternative foods are scarce.

Sufficient numbers of ti‐trees are presently recruited to ensure the persistence of that species, but a programme of rabbit control would be necessary to enable natural regeneration to perpetuate the sheoak population in the Coorong National Park.
Pollination ecology of Christmas Bells (Blandfordia nobilis): Effects of pollen quantity and source on seed set
Authors: ZIMMERMAN MICHAEL , PYKE GRAHAM H.
Published: July 2006

The effect of a number of experimental handpollination regimens on the numbers of seeds set by Blandfordia nobilis flowers was assessed. Individuals were found to be self‐incompatible and to require pollinator visits to set fruit. Pollen limited the female component of reproduction in the two populations studied while pollen source did not have a significant effect on the numbers of seeds set. Experiments using a stuffed honeyeater indicated that maximal seed set could be achieved after just one probe by the pollinator. Appreciable heterogeneity in flowering phenology, the number of seeds naturally setting and the number of seeds setting as a result of hand‐pollinations existed within a small area across a single flowering season.
The crown‐gap ratio (C) and crown cover: The field study
Authors: WALKER J. , CRAPPER P. F. , PENRIDGE L. K.
Published: July 2006

Crown cover can be used to describe or classify woody vegetation. However, current methods for the estimation of crown cover are difficult to apply and are time‐consuming. The objective of this work was to present a much easier method of field estimation and to define the limitations of the method.

The method uses the crown‐gap ratio (C), which is defined as the mean gap between crowns divided by the mean crown diameter. The relationship between values for the crown‐gap ratio and crown cover is of the form crown cover = k/(1 + C)2, where k is a constant.

The overall tasks are first, to develop a methodology to obtain estimates of C and crown openness in the field, and second, to estimate k.

In Part 1 we demonstrate that crown cover can be related to C when applied to woody vegetation. In Part 2 we consider a derivation of C, determine a value for k given a set of constraints, and outline some of the sampling implications of applying the method of crown cover estimation using C and k to field situations.

The field study provided data from which to plot crown cover against the crown‐gap ratio (C). The shape of the curve approximated a rectangular hyperbola. The regression of crown cover against 1/(1 + C)2 showed a strong linear relationship (R2= 0.995) and gave an estimate for k of 0.79 for the range of plant communities sampled.

The field study suggests that to investigate the effect of different spatial distributions of crowns and mixtures of crown sizes on C, a rigorous derivation of the relationship between crown cover and C is required.
Species‐richness and soil phosphorus in plant communities in coastal New South Wales
Authors: ADAM P. , STRICKER P. , ANDERSON D. J.
Published: July 2006

Species‐richness (recorded as number of species in 16 m2 quadrats), in more than 60 coastal sites developed over various substrata, exhibited a significant non‐linear relationship with soil total phosphorus extracted from associated soil samples. Although the general form of this relationship is not incompatible with a resource competition model, the significant proportion of the total variance accounted for by the species‐richness/phosphorus relationship suggests that a more detailed examination of phosphorus use at a community level will be profitable.
Mulga log mounds: Fertile patches in the semi‐arid woodlands of eastern Australia
Authors: TONGWAY D. J. , LUDWIG J. A. , WHITFORD W. G.
Published: July 2006

In the semi‐arid woodland of eastern Australia, soil mounds are often associated with fallen mulga (Acacia aneura) trees. Measurements of the physical and chemical properties of the soils in these mounds compared with surrounding soils, together with differences in herbage growth responses, indicate that these mounds are fertile patches, with possible importance as habitats for soil fauna and as refugia for a range of organisms during drought. The mound soil material may accumulate by fluvial, aeolian or rain‐splash deposition about the fallen log, however, some of the mound material was derived from termite feeding gallery structures. The surface feeding gallery material may be comprised of soil particles from within the mound or from tunnels and storage galleries below the mound, and probably depends on the termite species.
Co‐existence of three species of amphibious plants in relation to spatial and temporal variation: Field evidence
Authors: YEN S. , MYERSCOUGH P. J.
Published: July 2006

Changes in vegetation of Bushells Lagoon, a freshwater body fed intermittently by the Hawkesbury River in the Sydney basin, were studied over three scales of time: broad fluctuations in areas occupied by emergent plants over 28 years; fluctuations in their percentage cover over 21 months; and, over 6 months, seasonal variation in biomass of emergent plants of two native species Ludwigia peploides (Kunth) Raven ssp. montevidensis (Spreng.) Raven and Marsilea mutica Mett., and the introduced Myriophyllum aquaticum (Vellozo) Verde. Differences in distribution and abundance of plants observed between the three species were related to environmental variation in time and space. Wind and wave action varied along the shoreline, and emergent shoots of Myriophyllum were most abundant in sheltered conditions, floating leaves of Marsilea most abundant in relatively exposed conditions and emergent shoots of Ludwigia most abundant in somewhat intermediate conditions in the shallows. Chemical characteristics of the water varied in time but, unlike water temperature, had no obvious seasonal pattern. Seasonal change occurred in the biomass of Marsilea, and to a lesser extent in that of Myriophyllum, with smaller proportions of leaf material present in winter than in summer. Though water levels were apparently stable over a period of some years (1965–74), at other times they varied greatly through flooding and drought with related major change in cover of the three species. Co‐existence of the three species in the lagoon may be related to differences between their plants in establishment and growth following disturbance (regeneration niche), tolerance of wind and wave action (habitat niche), or seasonal growth (phenological niche).
Colonization, growth, and survival strategies of lichens on leaves in a subtropical rainforest
Authors: ROGERS R. W.
Published: July 2006

Rainforest leaves are a relatively short‐lived habitat which is well defined in both time and space, and which is occupied by a range of specialized lichens which might be expected to show survival strategies contrasting with those of other lichens. Changes in the lichen populations of individual leaves in subtropical rainforest at Ml Glorious, Queensland, Australia were observed for 1662 days. Over 1100 days elapsed before 50% of surviving leaves showed visible lichen thalli and the probability of colonization estimated from life tables did not exceed 0.42 ± 0.20 at any time. Porina epiphylla had a relative growth rate of 3.01 × 10−2 mm2 mm−2 week−1, a high value for a lichen. The relative growth rate of Strigula subtilissima, however, was 6.86 × 10−2 mm2 mm−2 week−1, the highest rate known for any lichen. Small size and high relative growth rates indicate that lichens on leaves have the most extreme ruderal strategy yet demonstrated amongst the lichens.
Habitat of the white‐footed dunnart Sminthopsis leucopus (Gray) (Dasyuridae: Marsupialia) in a logged, burnt forest near Bega, New South Wales
Authors: LUNNEY DANIEL , O'CONNELL MICHAEL , SANDERS JONATHAN , FORBES STEPHEN
Published: July 2006

In the winter of 1981, 9 months after an intense fire in November 1980 in the recently logged Mumbulla State Forest, the numbers of a small population of Sminthopsis leucopus had slightly increased, while the common species of small mammals had declined sharply from the previous winter. The study reported in this paper aimed to identify the habitat of S. leucopus. Ninety study plots were divided equally among three classes of forest (unlogged forest, and forest logged in 1979 and 1980), between two aspects (north‐ and south‐facing slopes), and among three topographic positions (ridge, midslope and gully). Plots were assessed on the basis of both floristic data and the structural components of ground, shrub and tree cover. The primary finding was that the habitat of S. leucopus was the treeless ridges and mid‐slopes with less than 51% ground cover in the logged areas of burnt forest. The floristic analysis showed that the vegetation subcommunities restricted to gullies, or carrying a ferny ground layer of vegetation, were not selected by S. leucopus. An analysis of movements of male S. leucopus identified two classes. ‘Resident’ males occurred on logged ridges and midslopes characterized by a floristic subcommunity of open forest with a grassy understorey.‘Explorer’ males moved through a variety of ridge habitats, including unlogged forest, and were spread more widely through the floristic communities. The pattern of habitat selection identified in this study shows S. leucopus to be ecologically distinct from the other species of small mammals in the forest and thus in need of special consideration in management programmes if it is to be conserved. Under the current regime, the uniform treatment of the forest leads to widespread stands of dense regrowth to the exclusion of the species and is inimical to its survival.
Demographic responses of Antechinus stuartii (Marsupialia) to supplementary food
Authors: DICKMAN C. R.
Published: July 2006

This study investigates the effects of supplementary feeding on populations of Antechinus stuartii, an insectivorous, semi‐arboreal species of dasyurid marsupial. Animals were live‐trapped, marked and released in three study areas in forest near Canberra, from September 1980 to November 1981. Supplementary food was supplied above ground in trees in one study area from January to November 1981, and in the second study area from January to May 1981, while the third study area was left unmanipulated as a control. The supplemented populations increased in numbers, mean body weights and survival, and showed decreased movements between traps and smaller overlaps in home ranges. Discontinuation of food in the second study area in May 1981 produced reciprocal shifts in these parameters. Reproduction, home‐range area, mean head‐body length, use of the terrestrial and arboreal parts of the habitat were largely unaffected by provision of supplementary food. In contrast to rodents, where fed populations usually increase rapidly due to immigration or increased reproduction, the supplemented populations of A. stuartii responded relatively slowly via increased survival of young. Population responses were probably retarded at the beginning of the experiments in summer due to the abundance of natural invertebrate prey, but became more obvious in winter when natural food was scarce. The added food probably contributed directly to increased numbers, survival and body weights, but may also have enhanced these parameters indirectly by allowing foraging animals to space out and avoid intraspecific intolerant contacts. These responses in A. stuartii suggest strongly that populations are limited by the food supply.
Community phenological patterns of a lowland tropical rainforest in north‐eastern Australia
Authors: HOPKINS M. S. , GRAHAM A. W.
Published: July 2006

Leaf‐fall, leaf‐flush (newly expanded leaves), flowering and fruiting were recorded monthly between April 1982 and May 1985 in 703 individuals of 99 species of trees, shrubs and herbs in a logged lowland, complex rainforest. Weekly water availability and demand were modelled using pan evaporation, rainfall, and a range of estimated maximum soil water storage. The water balance model indicated that rainfall distribution was an inadequate measure of the seasonal availability of water for growth and reproduction. Intermittent shortages in available water were predicted between October and February, well into what is the wettest season of the year in terms of long‐term rainfall averages. Adequate water was available in soil water stores through most of the August–October ‘dry season’.

Leaf‐fall, flowering, and fruiting all followed distinct seasonal patterns although appreciable levels of activity occurred in all months. Community leaf‐fall increased rapidly following an annual low in the very wet, February–May period, to a peak in August. The rapid increase in leaf‐fall activity was accompanied by pronounced depressions in flowering and leaf‐flushing and coincided with the period of minimum temperatures and insolation. There was no evidence to suggest that this leaf‐fall peak was accompanied or induced by drought. This ‘winter’ was followed by rising temperatures and insolation at a time when adequate soil water was usually available, and flowering activity (number of species, number of individuals, and total abundance) increased rapidly in August and peaked from September to October. The flowering peak was accompanied by a major leaf‐flush. Leaf‐flushing continued intermittently from October to February, a period characterized by maximum temperature, maximum insolation, and periods of predicted water stress when soil water stores were depleted during short, rainless periods. A second peak in leaf‐flushing coincided with the wet in March‐April. This was accompanied by a relatively small increase in leaf‐fall activity. Fruiting showed a bimodal peak from October to April each year. Prediction of functional relationships between climate and species and individual behaviour from community phenological patterns was considered to be inappropriate.
Effects of flower removal on abundance and behaviour of honeyeaters in heathland near Sydney
Authors: PYKE GRAHAM H.
Published: July 2006

Removal of almost all honeyeater nectar sources from a 5.6 ha area during February to July had no apparent effect on honeyeater nesting or total abundance. Behaviour in the experimental area was also generally unaffected except for the extent of nectar‐feeding which was significantly reduced for the most commonly observed species. The honeyeaters must have compensated for the nectar removal by flying to nearby productive areas to feed on nectar.

Nectar‐removal had no significant effect on the species composition of resident honeyeaters but did affect the species composition of all observed honeyeaters. Nectar removal resulted in a decrease in the abundance of the large and dominant Little Wattlebirds (Anthochaera chrysoptera) and an increase in the abundance of the other, smaller species.
Determinants of bird populations in an urban area
Authors: MUNYENYEMBE F. , HARRIS J. , HONE J. , NIX H.
Published: July 2006

The effects of suburb age and distance from remnant native vegetation on the species richness and density of bird populations in Canberra were studied from June 1982 to May 1983. Mean total number of bird species increased with age of the suburbs < 12 years old. The density of birds also increased with suburb age. The number of open forest and woodland species increased with the age of the suburbs but the number of grassland and exotic species remained largely unchanged. These increases in bird species richness and density represented a response to changes in habitat conditions over time and were not a direct response to the suburb age per se. Such habitat changes reflected the growth of trees and, to a lesser extent, the increased cover of shrubs. The numbers of open forest, woodland and grassland species decreased with distance of suburban sites from native vegetation areas. The number of exotic species, however, remained unaffected. The density of individual birds of grassland and exotic species increased with distance of sites from remnant native vegetation.
Vegetation and soil patterning in semi‐arid mulga lands of Eastern Australia
Authors: TONGWAY D. J. , LUDWIG J. A.
Published: July 2006

Vegetation and soil patterns across a 200 ha semi‐arid site 40 km north‐west of Louth, NSW, are described using plant cover data from line transects and soils data from points, sampled systematically (50 m intervals) across the site. A patterned sequence of alternating groves and intergroves with three vegetation types was identified: an Eragrostis eriopoda savanna occurring on runoff slopes (<0.5%) from low ridges, with a Monachather paradoxa savanna occurring at the toe of these runoff slopes (intergroves), followed by an Acacia anuera woodland occurring on runon areas (groves, either as discrete islands or more continuous along drainage lines). Data on landform, micro‐topography, and hydrological features indicate that the grove‐intergrove pattern is maintained by differential erosion–deposition processes similar to the dynamic erosion–transfer–sink geomorphic systems described for Central Australia.

This vegetation grove–intergrove patterning in Eastern Australia is similar to, but differs in detail from, such patterns reported for arid and semi‐arid Western and Central Australia. Groves or ‘bands’ of A. anuera in the Centre and the West tend to occur on the downslope side of ‘risers’ or on ‘convex slope‐breaks’ where in the East such groves occur in distinct 'steps’ or ‘flats’ in the landscape; there is a drop into the grove and a sharp ‘erosion‐scarp’ below the grove. A prominent ‘grass band’, identified by cluster analysis as the M. paradoxa community type, occurs immediately upslope of A. anuera groves in the East. The A. anuera groves in the East are also fertile’ patches as soils data demonstrate that groves have much higher levels of organic and exchangeable nutrients (and plant cover) than soils in the intergroves. This paper demonstrates that patterning in mulga lands is more extensive geographically, and has a wider climatic range, than previously reported.