摘要:

AbstractEstimates of seasonal abundance of larvae, nymphs and females of the paralysis tick, Ixodes holocyclus, were obtained by collecting ticks that engorged on small mammals and birds trapped in two localities in southeastern Queensland: Brisbane (wet sclerophyll forest) and Tamborine Mountain (cleared rain forest). The long‐tailed short‐nosed bandicoot, Isoodon macrourus, was the most common mammal trapped but small numbers of other marsupials, rodents and ground frequenting birds were also captured. Small numbers of five other tick species were also collected.In both habitats there was clearly one dominant generation of I. holocyclus;7er year, although the presence of all stages at most times of the year indicated overlapping of smaller cohorts. Females were most abundant in spring and early summer, larvae in summer‐autumn, and nymphs in autumn‐winter. I. holocyclus was abundant on I. macrourus and rare on most other mammals and birds captured. At the peak of abundance of each instar, each bandicoot dropped from 500 to 2000 engorged larvae, 100 to 200 engorged nymphs, and four to six engorged females.Life tables were compiled for the tick in both habitats and these indicate that there was relatively high survival from engorged larva to engorged nymph and thence to engorged female and that most mortality occurred between detaching of the engorged female and the detaching of the engorged larva.The tick was more abundant on bandicoots from cleared rain forest and rain forest edge, than on those from sclerophyll woodland. The survival of engorged larvae and nymphs of I. holocyclus and the larval productivity of engorged females were examined in a warm moist climate where the tick was abundant (Tamborine Mountain) and in a hotter dryer climate where the tick was rare or absent (Amberley). In both localities engorged larvae and nymphs survived to the next instar in all seasons of the year. On most occasions engorged females produced eggs which hatched.Mature bandicoots from tick infested areas showed little or no resistance to infestation with larvae or nymphs of I. holocyclus, whereas other small mammals from the same area showed an appreciable degree of resistance to the immature stages of the tick. Feeding larvae and nymphs exposed to normal light‐dark cycles in the laboratory detached during the afternoon and early evening. This behaviour and host resistance are discussed in relation to the daily activity cycles of host species, their habitat preferences, and their role as hosts for I. h

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1979.tb01564.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractThe distribution offish within the Seven Creeks River system, a tributary of the Goulburn River in the Murray–Darling basin, was determined primarily by a survey carried out during the summer of 1975–76. Information on the past occurrence of fish in the system was obtained from historical records. Seventeen species offish, eleven native and six exotic, have been recorded from the system. Habitat characteristics, cohabiting species and food habits are presented for each species recorded during the survey, and factors affecting present distributions are discussed. Siltation appears to have had adverse effects on native Murray cod,Maccullochella peeli, and Macquarie perch,Macquaria australasica, both of which were once common in the lower reaches of the system. The presence of Macquarie perch and the rare native trout cod,Maccullochellamacquariensis, in the upper reaches of the system is traced to fish released in 1921 and 1922. A nother native species, the western carp gudgeon, Hypseleotris klunzingeri, was first observed in the system only after it had been introduced into farm dams in the area in the mid 1960s. Relationships between native and introduced fish are complex. Although the food requirements of some native and introduced species overlap and some native fish have been found in the stomachs of introduced species, the only evidence of a substantial effect of an introduced species on a native species is the apparent fragmentation of the range of common mountain galaxiids,Galaxias olidus, by brown trout,Salmo trutta, whose numbers in the system were, until recently, augmented by continual releases of hatchery‐reared

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1979.tb01565.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractThis study investigates the impact of insect grazing on the establishment of plant populations from seed after bushfires in coastal plain woodland near Perth, Western Australia. Seedling germination was measured and individual seedlings were observed frequently to estimate survivorship and causes of mortality. Invasion rates of acridid grasshoppers into both small and large burnt areas were measured and palatabilities of seedlings to the most abundant grasshopper species were estimated. Escape of seedlings from insect grazing was influenced by both seedling palatability and area of burning. Grasshoppers were absent from large burnt areas for one to two years. In small burnt patches of vegetation, the patterns of grazing on seedlings were related to seedling palatabilities. These results are discussed in the light of current models of plant succession and the main conclusion is that fire is not a succession‐initiating disturbance in this ecosystem because the long association with fire has allowed the evolution of specific survival and recruitment strategie

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1979.tb01566.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractA test of random noise and an objective stopping rule are derived for use in association with hierarchical classification techniques. The apparatus required is replicated sampling and combinatorial analysis. The test and rule are based on the conditional probabilities of the number of sites all of whose replicates belong to the same group at each stage of the classification.These devices were tested on presence/absence data simulated from dependent multinomial trials. Where the number of groups became large the classification techniques proved somewhat unreliable because the groups were too similar. Usually clearer distinctions between groups will occur in nature. However, the test for random noise proved entirely successful and the stopping rule was quite successful, although, as one might expect, it was less successful when the classification itself was less successful.

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1979.tb01567.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractA new graphical method for displaying interrelationships within data on botanical composition of communities is described. It employs plotting roses of vectors where direction indicates species and length, proportional representation. The use and advantages of the method are discussed.

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1979.tb01568.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractPaperbark low closed forest, dominated by Melaleuca cuticularis, produced 430 g (dry weight), m−2of litter over a year, containing some 3.4 g.m−2of nitrogen and 77 mg.m−2of phosphorus. Twigs and bark made up more than 50% of the total annual litter fall. The twigs and bark contribute most of the nitrogen (54 %) and phosphorus (56%), compared with leaf fall (37% and 35%) and flower and fruit fall (8% and 9%). The fall of leaves, twigs and bark was primarily related to wind, and flower and fruit fall was greatest after flowering. The litter must make a significant contribution to the accretion of peat. Since the forest covers some 200 ha of the lower Blackwood River estuary, it may contribute some 8001 of litter to the ecosystem each year, containing some 6600 kg of nitrogen and 154 kg of phosp

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1979.tb01569.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractThe stratigraphy and pollen analysis of the basal 5.73 m of an 11.73 m core from the centre of Victoria's deepest lake is described. The hypothesis is advanced that at 16 100 B.P. a cool semi‐arid environment supporting a sparse or scatteredEucalyptus–Callitriswoodland with an understorey of grasses, Asteraceae and Chenopodiaceae dominated the region. From this time the lake level fell and was at its lowest between 15 000 B.P. and 10 000 B.P. At about the same timeCasuarinamigrated into the region asCallitris,Asteraceae and Chenopodiaceae declined. There was a period from 9600 B.P. to 9200 B.P. whenAcaciaandDodonaeawere common around Lake Bullenmerri, but these declined and were replaced by theEucalyptus‐Casuarinawoodland with a herbaceous understorey which persisted through the Holocene period in western Victoria until it was cleared by European set

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1979.tb01570.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractDifferences in niche utilization between two cohabiting eucalypt species (Eucalyptus signataandE. umbrassp.umbra) on North Stradbroke Island, Qld., are documented, including differences in morphology, growth patterns, seasonality, insect attack and a three month difference in peak seasonal uptake of most essential elements. The significance of these niche differences in aiding the coexistence of competing eucalypt species is supported by results using recent theoretical models from niche theory. It is noted that the presence of significant niche complementarity amongst cohabiting pairs of eucalypts will place hybrid offspring at a disadvantage relative to homozygous strains. This phenomenon helps explain the scarcity or absence of hybrids in a number of communities where potentially interbreeding species of Eucalyptus coexist. Co‐occurrence of species pairs which are capable of interbreeding will not be favored by environmental selection both because of the reduced production of homozygous offspring, and because of the reduced niche separation exhibited by taxonomically closely‐related species. Such differences help explain the scarcity of co‐occurrence of interbreeding pairs of species ofEucalyptusin relatively unperturbed natural commun

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1979.tb01571.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

An Introduction to Systems Analysis: with ecological applicationsJ.N.R. Jeffers, Edward ArnoldBehavioural Ecology: an Evolutionary ApproachJ. R. Krebs and N. B. Davies, eds.

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1979.tb01572.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY