摘要:

AbstractAcacia victoriae, Cassia nemophilaandC. phyllodineaare shrubs which occur throughout large areas of arid and semi‐arid Australia. This paper examines aspects of the dynamics of the seed‐banks and seedling populations of these plants to determine their influence upon recruitment frequency. Seed‐banks in the soil are large, ranging from 50 to 3900 seeds m‐2forA. victoriaeand from 5 to 400 seeds m‐2for Cassia spp. A large proportion (ca. 80%) of these seeds are viable. Seedling densities soon after emergence range up to 25.7 m‐2forA. victoriaeand up to 21.7 m‐2forCassiaspp. Any individual cohort of seedlings represents only a small proportion (<6%) of the total seed‐bank. Most viable seeds fail to germinate even when adequate moisture is available. Seedling mortality rates are high (ca. 100%) during the first 12 months after germination. If recruitment of these shrubs is intermittent, it is most likely a result of low seedling survival rather than infrequ

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1987.tb00944.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractThe 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 possi

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1987.tb00945.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractA 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 al

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1987.tb00946.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractThe numbers of alien plant species naturalized on Kangaroo Is., South Australia, at different times were examined and compared with those from an adjacent part of the mainland, the Encounter Bay area. The establishment of new species appears to have been accelerating and the rate of acquisition is around 50% faster on the mainland than on the island. Flinders’ Chase, a National Park at the western end of Kangaroo Is., has been acquiring alien species more slowly than the rest of the island. Land use patterns are a more effective barrier to the invasion of alien plants than a 15 km stretch of se

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1987.tb00947.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractPrevious studies have shown that the quokka(Setonix brachyurus:Marsupialia) experiences a very extensive proliferation ofSalmonellainfections 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 interactionof Salmonellawith 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 ofSalmonellain 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 ofSalmonellain natural and disturbed areas in Western Australia, and of management of the problems created by proliferation ofSalmonellain the Rottnest Is. quokk

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1987.tb00948.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractIncreased 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 ofMelaleucaandCasuarina obesadominated the seasonally inundated regions of the lake bed. Aeolian deposits of higher elevation were dominated byEucalyptus loxophleba, Allocasuarina huegelianaor species ofBanksia.Woodland ofE. oleosavar.longicornisandE. salmonophloiaoccurred 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 inMelaleucasp. andC. obesawere due to increased levels of salinity. Deaths and low vigours inE. rudiswere 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.

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1987.tb00949.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractDaily routine 3 p.m. meteorological data for Melbourne, Victoria, were processed to provide estimates of maximum forest fire danger index (including soil‐water deficit), potential number of days for failure of fire suppression for given quantities of fuel, and potential number of days for optimal prescribed fuel reduction burning in eucalypt forests given the same quantities of fuel. Although two models for estimating soil dryness gave widely different results, the effect of these differences on the value of the McArthur forest fire danger index (FFDI) was relatively small overall. However, over the 28 years of record, the number of ‘extreme’ days given using the Mount dryness index was 50% greater than that given by the Keetch‐Byram index.The number of forest fires in Victoria (as a whole) was found to be related to 3 p.m. FFDI (for Melbourne) and to the incidence of weekends or public holidays. Potentially, bushfires near Melbourne would be ‘uncontrollable’; that is, with an intensity greater than 4000 kW m‐1on level ground, on an average of about 100 days per year (at 3 p.m.) if ignition were to occur where litter fuel weights were about 301 ha‐1. However, if fuel weights were less than 81 ha‐1, the potential number of ‘uncontrollable’ fires would be near zero. Using equations to predict conditions ideally suited to safe fuel reduction burning at 3 p.m. the average number of appropriate days per year increased from zero at a fuel weight of near 71 ha‐1to a maximum of 14 at 15 t ha‐1. The extent to which the models used in this study are accurate is arguable

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1987.tb00950.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractThe relationship between vegetational type and a number of soil chemical factors was examined in secondary successions from fire‐maintained eucalypt/grass to climax rainforest communities growing on uniform granitic soil parent material. Canonical variates analysis, which utilized the following variables: pH; loss on ignition; total N, P, K, Ca, and Mg; cation exchange capacity and exchangeable Ca, K, and Mg; and potentially mineralizable N, revealed close overall similarity between surface soils of adjacent types, and significant differences among those of types distant from each other in the successional sequences. Exchangeable Ca, mineralizable N, total N. P, and Mg, and pH all differed significantly among soils of the vegetational types. However, the only identifiable gradients in soil properties that were detected within a successional sequence were in total and mineralizable N, which tended to increase, and pH, which generally tended to decrease with progression towards the climax vegetation. Nitrification was promoted by the presence ofAcacia dealbataand apparently inhibited by the presence ofLeptospermum lanigerum;it was more rapid in soils beneath late successional vegetation than in those from climax vegetation or early stages of succession, and was inhibited in soil from old (>200 years) grassland. It was concluded that differences among soils in chemical composition and rates of mineralization of N were due to differences in species composition of the vegetational types that they carried for the time bein

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1987.tb00951.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

The community structure of micronekton from an oceanic eddy Victoria WadleyThe distributions of fish and decapods in seagrass beds Johann D. BellA demographic analysis of reproduction inAcacia suaveolens(Smith) Willd. (Mimosaceae) David A. Morrison

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1987.tb00952.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Book review in this articleEcological Communities. Conceptual Issues and the EvidenceEdited by D. R. Strong Jr, D. Simberloff, L. G. Abele and A. B. Thistle M. P. AUSTINThe Evolutionary Ecology of Ant‐Plant MutualismsAndrew BeattieEnvironmental ChemistryPeter O'Neill J. S. BURGESSBiology of Chrysopidae. Series Entomologica, Volume 27Edited by M. Canard, Y. Semeria and T. R. New, Dr W. Junk K. LAMBKINThe Dynamic Partnership: Birds and Plants in Southern AustraliaEdited by H. A. Ford and D. C. Paton, D. J. Woolman G. H. PYKEHot Deserts and Arid Shrublands, A. Ecosystems of the World 12AEdited by M. Evenari, I. Noy‐Meir and D. W. GoodallHot Deserts and Arid Shrublands, B. Ecosystems of the World 12BEdited by M. Evenari, I. Noy‐Meir and D. W. Goodall B. H. WALKERTropical Zooplankton. Developments in Hydrobiology 23Edited by H. J. Dumont and Tundisi IAN A. E. BAYLYLandscape Ecology. Theory and ApplicationZev Naveh and Arthur S. Lieberman R. A.

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1987.tb00953.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY