bluuebunny/crossref_metadata_2025_split huggingface dataset:
An improved numerical method for the analysis of a floristic pasture survey
Authors: WILLIAMS W. T. , GILLARD P. , EDYE L.A. 
Published: July 2006

AbstractA classical ecologist is usually equally interested in groups of sites and groups of species, so that symmetrical numerical models are appropriate for the elucidation of floristic pattern. It is suggested that an agronomist is primarily interested in the pattern of site‐ (usually paddock‐) groups, and is only interested in those species‐groups whose members are present in sufficient abundance to be quickly recognizable, and which serve to discriminate clearly between the site‐groups. An‘asymmetric inverse’model is defined for the purpose of extracting species‐groups of this type, which can be combined with a site classification into a two‐way table. The method is applied to a floristic survey carried out at the end of a grazing experiment, and is shown to produce meaningful and profitable results.
Self‐thinning in Trifolium subterraneum not affected by cultivar shape
Authors: WESTOBY MARK 
Published: July 2006

AbstractAs it was thought that self‐thinning in crowded plant populations might be influenced by the shape of the plants involved, self‐thinning was examined in five cultivars of Trifolium subterraneum. The height of these cultivars is fixed after early growth, being determined mainly by petiole length which itself varies between cultivars. No detectable differences between cultivars were found, and it is argued that only wore considerable differences in shape than those reported here would have detectable effects.When plants can only grow radially but not in height, it is to be expected that log‐log self‐thinning curves would have a slope of ‐1, but these Trifolium populations had the – 3/2 slope usually found for species which exhibit continuous growth in height. This finding remains unexplained.
Soil water regimes and water extraction patterns under two semi‐arid shrub (Atriplex spp.) communities
Authors: SHARMA M. L. 
Published: July 2006

AbstractSoil water regimes and water extraction patterns estimated over a period of two years are described for two plantation communities of semi‐arid shrubs, Atriplex vesicaria Hew. ex Benth. and A. nummularia Lindl., growing on the same soil type under identical climatological conditions near Deniliquin, New South Wales.In spite of poor water flow properties of the soil, surface run‐off was negligible.About 90% of the extractable water was stored in the top (45 cm) soil layer. Both species withstood exceedingly low water potentials, although A, vesicaria reduced soil water to a much lower water potential than did A. nummularia. Water potentials at depths below 60 cm were always – 15 bars and remained constant. Water extracted beyond –15 bars amounted to 41% more than the water available within conventionally accepted water potential limits (between –0.3 to – 15 bars). During Slimmer, the plant water potential of A. vesicaria fell to much lower values than that of A. nummularia. Relationships between relative leaf water content and plant water potential differed between the two species, and the suggestion is made that at low plant water potential, leaf targidity of A. vesicaria would be higher, and thus this species would have a higher tolerance to desiccation.On a yearly, half‐yearly and even a quarterly basis, evapotranspiration (FT) of the two communities did not differ. Fortnightly FT rates were similar during winter but during early summer, the initial ET rate of A. vesicaria was higher than that of A. nummularia; A, nummularia can therefore conserve water for later use. These differences in water extraction patterns and evapotranspiration were associated with differential rooting characteristics and probably differential stomatal functioning. The relationships between fortnightly ET/FO (ratio of actual evapotranspiration to that from a Class A pan) and profile water content, for both communities, were linear but different.
The effects of temperature on germination and early growth of three plant species indigenous to Central Australia
Authors: ROSS M. A. 
Published: July 2006

AbstractThe temperature responses of the perennial grass Eragrostis eriopoda Benth., an all‐season annual grass (Enneapogon polyphyllus Domin.) and a cool‐season annual forb (Lepidium muelleri‐ferdinandi Thell.) were studied in two experiments, one during germination and the other during the establishment phase.In the first experiment, extreme differences in the response of germination to temperature occurred between species. The optimum was 42°C for Eragrostis and 15 to 21° C for Enneapogon and Lepidium although Enneapogon tolerated higher temperatures than did Lepidium. The effect of temperature on speed of germination is discussed.In the second experiment, seedlings were assigned to six day/night temperature regimes ranging from 24/16 C to 45/31 C for three weeks in a phytotron. Both grasses responded positively to temperatures tip to 30/22°C with little further change up to 45/37° C, while Lepidium died at temperatures greater than 30/22° C.The experimentally determined response to temperature reflected field observations of seasonal establishment patterns for each species. The ecological significance of the results is discussed.
Comparisons of habitat structure and plant, arthropod and bird diversity between mainland and island sites near Perth, Western Australia
Authors: ABBOTT IAN 
Published: July 2006

AbstractDetailed estimations of habitat structure, plant species diversity and diversity of arthropods were made at six 4.0 ha sites, two on mainland Western Australia near Perth and four on adjacent islands. The number of resident passerine bird species was also recorded at each site. Plant species diversity, and horizontal foliage diversity (=patchiness) varied only slightly between sites. There were significant positive correlations between arthropod Order diversity and bird diversity, and between vertical foliage diversity and bird diversity.In both Acacia and dune scrub, the Rottnest Island sites had more individuals of arthropods than the mainland sites but these belonged to fewer Orders. Numerical imbalance between arthropod Orders on Rottnest Island probably results from diminution of predators (passerine birds) there. As the actual number of arthropods is higher on the islands, the absence of so many species of passerine birds may result from other factors (ecological and historical).
The effects of a severe drought on the morphology of the adrenal glands and other indices of health in the red kangaroo Megaleia rufa (Desmarest) in north‐western New South Wales*
Authors: MYERS K. , BAILEY P. J. , DUDZIŃSKI M. L. 
Published: July 2006

AbstractDrought adversely affects health and reproduction in red kangaroos (Megaleia rufa) (Desmarest). There is a significant drop in body weight in adult kangaroos, and growth rates of pouch young are depressed. In adult males both lobes of the pituitary gland decrease in size. All zones in the adrenal glands become smaller and lipid stores increase. In adult females the posterior lobe of the pituitary increases in size and, although all zones in the adrenal glands shrink the evidence suggests continued stimulation of the Zonae fasciculata and glomerulosa. The decrease in size of the adrenal glands is accompanied by cortical folding and nodulation and other structural changes.Growth curves of pouch young are shown to fit the Johnson‐Schumacher curve Y = A * exp [‐b/(x + k)].The data substantiate the findings of earlier workers but suggest that anoestrous female red kangaroos suckling small young may be better adapted to withstand drought than males.
Time resources and population dynamics in insects
Authors: KITCHING R. L. 
Published: July 2006

AbstractAn account is given of the way the temperature‐mediated processes of development and locomotor activity in insects interact with the availability of essential resources to reduce lifetime fecundity below the potential predicted from laboratory performance. Current work on the sheep blowfly, Lucilia cuprina, is used to illustrate the points made wherever possible.Brief reviews of the ecologically important relationships between rate of development and temperature and level of activity and temperature are presented. The ways in which such laboratory‐derived relationships may be applied in the interpretation of field results are described and discussed. The notions of time as a resource and of protein‐food, mates and oviposition sites as limiting resources are presented and these provide the basis of a time/resource/fecundity mechanism limiting reproductive performance during the life‐time of a female insect. Field and laboratory data are used to show the potentiality of such a mechanism for reducing life‐time fecundity in the sheep‐blowfly.
The population dynamics of the bushfly: the elucidation of population events in the field
Authors: HUGHES R.D. 
Published: July 2006

AbstractAt three well differentiated sites and over three seasons bushfly abundance at first increased rapidly, but then stabilized or fell slowly through the apparently favourable periods of summer and early autumn, before a rapid end of season decline. Analysis of the characteristics of flies taken regularly in a sampling programme allowed the sequence of population events involved to be elucidated. Adult flies immigrated in spring. They and their first progeny were comparatively large but in the subsequent locally bred generations a progressive decrease in fly size was associated with a gradual decline in the levels of natality and a gradual increase in the levels of mortality. Between site differences could be traced to variation in the balance of these changes. Climate may have a large role in the population dynamics of the bushfly but its effects are largely indirect. Fuller understanding of the bushfly life system requires some way of synthesizing the effects and interactions between the many factors involved.
The capacity for increase at a low temperature of several Australian populations of Sitophilus oryzae (L.)
Authors: EVANS D.E. 
Published: July 2006

AbstractThe capacity for increase (Ic) of one laboratory and seven field populations of young adult S. oryzae from different sites in Australia was determined over a thirty‐week period at 15°C, a supposedly marginal temperature, in wheat of 14% moisture content.The average value of Ic was 0.0838 ± 0.0017 and the populations comprised three significantly different groups. Variations in the net rate of increase per generation (R0) which averaged 34.7±1.71, had a major effect on the value of rc whereas variation in the cohort generation time (Tc), which averaged 41.6±.23 weeks had only a minor effect. The survivorship of adults of the populations did not differ significantly and 93% of females were alive after thirty weeks. Estimates of rc based on a fifteen‐week period and on an amended value of Tc differed little from those over thirty weeks.The capacity for increase at 15°C of a given population was found to be correlated with its fertility at 27°C and with its body‐weight rather than with its cold‐tolerance, as evidenced by chill‐coma temperature, or with its previous temperature‐history.The temperature experienced by the immature stages of weevils had a profound effect on rc in that weevils reared at 15 and 27°C had respective values of 0.0350 and 0.0707 when subsequently cultured at 15°C.Because all observed values of rc were higher than expected, possible errors in method were considered. An alternative estimate of R0 agreed closely with that observed and indicated that only 17% of the immature stages survived at 15°C. Metabolic heating due to the higher than expected population density shortened the duration of the immature stages by 7% but did not affect their survival.
The capacity for increase at a low temperature of some Australian populations of the granary weevil, Sitophilus granarius (L.)
Authors: EVANS D. E. 
Published: July 2006

AbstractThe capacity for increase (rc) of one laboratory and seven field populations of young adult S. granarius from different sites in Australia was determined over thirty‐two weeks at 15°C in wheat of 14% moisture content.The mean value of rc was 0.0704 ±0.0016 and the populations differed significantly with respect to this parameter. Variation in the net reproductive rate (R0), which averaged 25.4± 1.29, had a greater effect on the value of Ic than did variation in the cohort generation time (Tc), which averaged 45.7±0.37 weeks. The populations did not differ significantly in terms of adult survivorship and 94% of females were still alive at thirty‐two weeks. The maximum rate of oviposition, about ten eggs per female per week, was achieved in the eighteen‐twenty week age‐interval. About 41% of the immature stages survived to adulthood. Estimates of rc over a twenty‐four week period were only slightly lower than those over thirty‐two weeks.The capacity for increase at 15°C of a given population was shown to be correlated with its fertility at 29°C, an optimal temperature, and with its body weight rather than with its cold tolerance, as indicated by its chill‐coma temperature, or its previous temperature‐history.The temperature experienced by the immature stages had a marked influence on rc in that weevils reared at 15°C and 27°C had respective values of 0.0654 and 0.0786 when subsequently held at 15°C.The differences in the survivorship and fertility of S. granarius and S. oryzae (L.) when both species were reared at 15°C are considered.
The effects of temperature and photoperiod on the morphology of the egg‐pod of the Australian plague locust (Chortoicetes terminifera Walker, Orthoptera: Acrididae)
Authors: WARDHAUGH K. G. 
Published: July 2006

AbstractChortoicetes terminifera can detect absolute differences of both temperature and photo‐period, as well as the directional change of these parameters. Insects subjected to long‐day conditions, or to an increase in photo‐period during development lay long straight pods, whereas those subjected to short days or to a decrease in photoperiod during development lay short pods, which are usually curved and/or laid obliquely. Temperature does not affect oviposition behaviour at long photoperiod, but at medium and short photoperiod, high temperature or an increase in temperature promotes the production of long pods, whereas low temperature or a decrease in temperature stimulates the production of short pods. When temperature and photoperiod change in opposite directions, the effects of photoperiod override those of temperature. The significance of these findings is discussed in relation to egg development and survival.
The heath‐savannah problem: the effect of fertilizer on sand‐heath vegetation of North Stradbroke Island, Queensland
Authors: SPECHT R. L. , CONNOR D.J. , CLIFFORD H. T. 
Published: July 2006

AbstractA balanced fertilizer treatment ‐ equivalent to that optimal for pasture development on the infertile sandy soils of the Coastal Lowlands of south‐eastern Queensland ‐ was applied to a heathland stand on North Stradbroke Island in 1968, 3 years after the vegetation had been razed by bushfire. The fertilized and control plots were examined in detail in 1968 (before application of fertilizer), in 1969 and in 1976.Eight years after fertilizer treatment the heath species have declined in density and/or biomass. The native grass, Themeda australis, responded to fertilizer and is expanding into gaps as the heath species die. A few composites and grasses are invading the fertilized plots.
Size‐class analysis of coastal scrub and woodland, Western Port, southem Australia
Authors: HAZARD JACQUE , PARSONS R. F. 
Published: July 2006

AbstractCoastal scrub and woodland of varying fire history and variously dominated by Banksia integrifolia, Leptospermum laevigatum and Leucopogon parviflorus were studied using size‐class analysis of the dominant species. Transects from L. laevigatum scrub to B. integrifolia woodland were recorded in areas burnt (a) 32 years ago and (b) more than about 80–100 years ago. Post‐fire invasion of B. integrifolia by L. laevigatum is described in the younger stands. Only Leucopogon parviflorus shows widespread seedling establishment in the absence of fire. In the old L. laevigatum stands, there is good evidence that this species is dying out and being replaced by L. parviflorus which appears to be the climax dominant in non‐Banksia areas in the absence of fire. Although B. integrifolia seedling establishment is very rare in mature stands, no degenerate Banksia stands were found, so it is not yet clear whether this species is self‐maintained in the absence of fire.
Flowering phenology of some native perennial tropical grasses from north‐eastern Australia
Authors: TOTHILL J. C. 
Published: July 2006

AbstractThe division of north‐eastern Australia into tropical and sub‐tropical zones at approximately the latitude of 20° S, as suggested by the flowering phenology of Heteropogon contortus, is supported by studies on other perennial grasses of the native pastures. A progressive evolution away from an obligate short‐day flowering response which characterizes the tropical forms of Bothriochloa bladhii, perhaps Themeda australis, and the exclusive tropical species Dicanthium tenuiculum, through a quantitative short‐day response, as in the more widely distributed B. decipiens var. cloncurrensis, to the day‐neutral or opportunistic and largely subtropical species of B. decipiens and D. sericeum, is suggested as a sequence of flowering strategies leading to wider adaptation into the sub‐tropics.There is evidence from here and elsewhere that tropical forms or species of perennial grasses are grosser than their subtropical counterparts and this is coupled with their short‐day flowering behaviour. The evidence suggests that B. decipiens and D. sericeum are the evolutionary products of taxa nearer to B. decipiens var. cloncurrensis and D. tenuiculum which exhibit day‐length control of flowering.
Breeding and age structure of the population of Macropus parma on Kawau Island, New Zealand
Authors: MAYNES G. M. 
Published: July 2006

AbstractThe parma wallaby, Macropus parma, is one of four species of wallaby introduced on to Kawau Island, New Zealand, in ahout 1870. A sample of sixty‐four parmas was shot on the island in February 1973 to provide information on breeding activity and age structure of the population. Incidental data were also collected from the tammar wallaby, Macropus eugenii, which is the other common species on the island.Neither the sex ratio of the shot sample of parmas (thirty‐seven males to twenty‐seven females) nor that of the tammars (eleven males to eleven females) differed significantly from parity.Onset of sexual maturity of female parmas on Kawau I. was delayed when compared with that of captive females. One female was estimated to have bred at 19 months old but most females in the sample were not mature until 2 years old and a few not until 3 years old. In contrast, female tammars became sexually mature at about 12 months. There did not appear to be any delay in the onset of sexual maturity of male parma wallabies.In the shot sample, none of sixteen female parmas capable of having a young were carrying a pouch young whereas nine of ten female tammars had a pouch young. The mean date of birth of these latter young was 30 January (range 18 January ‐ 11 February) which is consistent with the breeding season of tammars in Australia. Among the mature female parmas two had recently mated, six were in pro‐oestrus and six were in anoestrus, indicating that the breeding season in 1973 had just commenced. Estimated months of birth for all parmas under 3 years of age suggested that breeding was continuous in 1970–71 but that there had been a defined breeding season in 1972 with births occurring between March and July.There was an excess of 1– and 2–year‐old parmas in the sample. This was the result of continuous breeding in 1970–71, presumably due to the provision of pasture on farmland being developed on the island. A sample of thirty‐three tammar skulls resulting from a shoot in November 1972 did not show a nmilar excess of 1– and 2–year‐old animals as this species has a rigidly defined breeding pattern and the females can produce only one young a year.
Concurrent changes in plant weight and soil water regimes in herbaceous communities in Central Australia
Authors: ROSS M. A. 
Published: July 2006

AbstractTwo studies of arid zone plant communities are described. In the first, the perennial grass Eragrostis eriopoda was sampled over 8 months for dry weight and water stress of tops, and water content and tension of soil to a depth of 150 cm. In the second, lasting 2 years, pure Eragrostis and pure Aristida con‐torta (annual) communities were sampled for dry weight of tops and roots and soil water content. Plots of naturally occurring mixtures of Eragrostis and Aristida were also studied.During periods of prolonged high soil water content, perennial communities greatly out‐yielded annuals (1200 and 260gm‐2 respectively). During prolonged droughts all communities yielded less than 100 gm‐2.Perennial root systems were larger than for annuals. The weight of annual roots varied little with season as distinct from perennials which varied greatly. Maximum weight of annual roots occurred in the top 10 cm of soil; the zone of maximum rooting by perennials was 10–30 cm. Water loss from annual, perennial and bare plots was similar and extended throughout the measured profile. Two gradients of soil water tension of opposite signs developed during prolonged drought. The greater was due to evapo‐transpiration and the lesser developed below the zone of recharge.On average. Eragrostis grew 4.6 times faster than the annuals which enjoyed a marginally more favourable water regime. In a mixture which had received one heavy simulated grazing the presence of annuals reduced the growth of Eragrostis by 68%, suggesting that the invasion of Eragrostis by annuals would seriously reduce productivity.
The ecology of granite outcrops at Wilson's Promontory, Victoria
Authors: ASHTON D. H. , WEBB R.N. 
Published: July 2006

AbstractRock outcrops on spurs and summits on Wilson's Promontory tend to be more prevalent on hot dry slopes than cool moist ones. In this comparatively moist climate, the rock outcrop vegetation can be grouped into high altitude, low altitude and coastal types. The surrounding rock‐heath is characterized below 400–500 m by Kunzea ambigua and above this altitude by Callistemon pallidus. Moss aprons of Campylopus bicolor on rock faces are often held in place by roots of surrounding shrubs on slopes up to 20°. Bryophyte and lichen communities vary with altitude, and annuals and geophytes are common. Fire may result in retrogression if forests and shrub zones are destroyed and humic top soil burnt or eroded away. Fossil root‐grooves occur in granite on the summit of Mt Latrobe and are the legacy of a cloud forest of Nothofagus cunninghamii. The rock‐heath species are more drought resistant than the‘climax’tree species and may develop very low water potentials. The rate of succession may be correlated with the highly variable rate of decay of each individual block of granite.The soils of the early successional stages are veneers of humic sands enriched with hill‐wash, whilst the soils of the forest stages vary from duplex podzols to gradational podzolic soils of much greater moisture storage. Woody plant establishment is mostly initiated along rock joints: the rock surfaces and boulders so by‐passed are colonized by more mesic species. Many zonations appear to be static since advances are cancelled by retreats.The rate of succession on bare granite is controlled by local climate, altitude, slope, fire and macro‐and micro‐jointing patterns. In general, the early stages bear strong similarities over a relatively wide range of climate. The so‐called climaxes which have developed represent a continuum in response to the complex environments found on Wilson's Promontory.