摘要:

AbstractIn the last few years there has been a marked growth of interest in the recent history of climate. The evidence of secular variations in climatic parameters during the last few centuries has implications for ecologists studying forests containing long‐lived species. Such species record aspects of past climate in their annual growth‐rings and in their population structures. The study of annual growth rings in Australian trees is still in its infancy. The concepts and techniques of dendrochronology and its sub‐fields dendroecology and dendroclimatology are outlined. A species by species account of dendrochronological studies employing Australian trees is presented. As most of the results are unpublished, the treatment is selective and intended to illustrate the potential of, or progress with, a particular tree species.The greatest potential for dendrochronology in Australia lies with the endemic Tasmanian conifers in the generaAthrotaxis, DacrydiumandPhyllocladus. Not only do these contain very long lived individuals (e.g.>2000yr, Dacrydium franklinii)but also they have the most suitable ring characteristics. Chronologies of about 1000 yr and 780 yr are being prepared forA. cupressoidesandPhyllocladus aspleniifoliusrespectively. There is good regional cross‐dating within species, and to a lesser extent between species, giving promise of a detailed reconstruction of past climate for Tasmania.Relatively short chronologies may be developed on the mainland usingCallitris.This species may provide a proxy rainfall record for semi‐arid areas which would be invaluable to their future management. The possibilities for developing chronologies using long‐lived tropical rain‐forest species in Queensland are discussed. The most abundant tree species of the continent as a whole, in the generaEucalyptusandAcacia,appear to be generally unsuitable for standard dendrochronological methods aimed at climatic reconstruction although there are some exceptions. For many dendroecological studiesEucalyptuswill be the only species available, and it should certainly not b

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1978.tb01184.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractAbove‐ground nutrient return to the soil was estimated by studying forest floor leachates for up to 2 years in two eucalypt forests(Eucalyptus obliquaandE. regnans)and two nearby conifer plantations(Pinus radiataandPseudotsuga menziesii)near Narbethong in southern central Victoria. Forest floor leachate volumes were recorded approximately once a month and samples were analysed for pH and potassium, sodium, magnesium, and calcium concentrations.The volume of forest floor leachate was greater in the eucalypts than in the conifers. This was attributed to greater interception losses of water by the conifers.Forest floor leachate chemistry underwent regular seasonal fluctuations which were similar for each of the four forest types. Acidity was highest in spring and autumn and lowest in summer. Cation concentrations were highest in autumn and lowest in spring. This behaviour was attributed to changes in climate and in rates of litter decomposition.In contrast to cation concentrations, cation quantities entering the soil in forest floor leachate showed no pronounced seasonal variations although they tended to be high in winter. The quantities of cations added to the soil in forest floor leachate varied with forest type, and were significantly higher inE. obliquathan in the comparableP. radiatastand. Greater quantities of acid were added to the soil underP. radiata.TheP. radiatasoil contained lower quantities of exchangeable cations than theE. obliquasoil. This was consistent with the observed differences in forest floor leachate chemistry. Unlike theP. radiatasoil, theP. menziesiisoil did not appear to be depleted in exchangeable cations.It was concluded thatP. radiatahad depleted the exchangeable cation reserves in the soil studied but that the full significance of this is still unknow

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1978.tb01185.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe flora of Mawson Rock is fairly depauperate; the two commonest lichens areBuellia frigidaandCaloplaca elegansand the only two mosses areBryum algensandGrimmia lawiana.The lichens form open colonies on exposed rock, and closed patches on sheltered aspects. The mossfields are small and confined chiefly to gravels on northerly aspects receiving snow‐bank melt waters. The moss colonies form cushions, turfs or hummocks and may be contorted by cryoturbic processes. Larger colonies thus contain greater cores of sand and gravel. Mature cushions ofBryum algensare up to 25 years old, but the deepest peats are certainly much older. The small biomass of green moss in the most sheltered sites at Mawson is similar to comparable mossfields on the exposed plateau of subantarctic Macquarie Islan

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1978.tb01186.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractA study of soil and vegetation characteristics within a small area of coastal heath near The Gap, Albany, Western Australia, showed that significant differences exist in plant species composition between podzol and non‐podzol (calcareous) soil environments. Leaf extracts of common plant species from podzol, non‐podzol and transitional soil sites were tested for their ability to complex with iron. Only those species on the podzol and transitional soils proved to have this ability.Soil column experiments tested the rates of iron mobilization and results indicate that the podzol vegetation elutant solution, which was found to contain the iron‐complexing agent gallic acid, was superior to the non‐podzol vegetation elutant solution in the rate at which it mobilized iron.It is suggested that initiation of podzolization is due to the presence of gallic acid in the leaves of certain of the species in the coastal heath association, and that the pattern of podzol distribution can be linked to both plant succession and inherent differences in soil parent m

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1978.tb01187.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractFour homograms are presented which enable the field worker to identify 168 genera of rainforest trees in Papua New Guinea. These keys are based on simple field characters such as sap colour and leaf features. To assist identification, illustrations are given of the most important field characters. With modifications similar keys could be developed for most rainforest situations. This method of key construction could be widely applied in both botanical and zoological fields.

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1978.tb01188.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe results of a study of the food of emus,Dromaius novaehollandiae, in inland Western Australia show that they feed on a great variety of fruits, seeds, flowers, insects and green herbage of annual and perennial plants. Shrubs provide most of the food in spring and autumn (September to March), annuals in the autumn and winter (April to August) and insects are taken whenever they occur in abundance, usually in autumn and spring.Although shrubs provide a reliable supply of food in summer, annuals often produce little in the autumn and winter so that emus would have to move extensively to keep in contact with a supply of food. Records from other parts of Australia indicate that the type of food eaten by emus is similar throughout the continent, but the precise species eaten varies from time to time and place to place.Some incidental observations on characteristics of the digestive system of emus are reported. Large quantities of mineral material are carried in the gizzard and individual items may be retained for 3 or 4 months. The acidity of the anterior sections of the gut make bacterial action unlikely. The crude form of copography has been observed. Some food passes through the gut in 3h but other material from the same intake may be retained for at least 48 h.The emu's diet is nutrient‐rich, but only a catholic taste and great mobility ensure that it is able to find a continuous supply of foo

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1978.tb01189.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractHabitat selection by seven species of small mammals was investigated in three areas of heathland in Victoria. A total of 12 120 trapnights over 22 months was used to assess preference for different vegetation groups formed by clustering trap sites on (a) floristic and (b) structural criteria.Rattus lutreolusproved to have both floristic and structural requirements. Seasonal changes in distribution in relation to rainfall appeared to be dependent on soil type. Greatest movement occurred on sandy podzol soils.Pseudomys shortridgeiselected the most diverse vegetation types.Rattus fuscipespreferred wet, structurally complex vegetation.Mus musculusappeared to fill the niche ofAntechinus minimusand partially replaceA. stuartiiandA. flavipeswhenAntechinusspp. were absent.M. musculusseems to commonly fill three niches in these heathlands: fossorial insectivore, scansorial insectivore and immediate post‐fire omnivore.A small mammal community structure of five major food niches may be common to both heathland and forest communities of south‐eastern Austra

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1978.tb01190.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe regeneration of coastal heath after disturbance by mineral sand mining was studied on mid‐seral stages from 4 to 11 years old at Hawks Nest, N.S.W. The main purpose was to gain some understanding of factors influencing recolonization by pioneer species of small mammals such asPseudomys novaehollandiae.Changes in floristics and vegetation structure with time were studied as possible contributing factors together with environmental variables. An apparently linear relationship was found between plant species diversity (X1) andP. novaehollandiaebiomass which was also correlated with an index representing the proportion of heath species present (X2). Both plant species diversity andP. novaehollandiaebiomass showed a linear increase with regeneration age.A multiple regression analysis revealed a predictive equation explaining 96% of the variation inP. novaehollandiaebiomass (Y): Y=‐7.92 + 1.21X1+3.92X2‐ 3.09X3The third variable (X3) is a measure of soil hardness. A path diagram using contribution coefficients based on a partial correlation analysis included the effects of vegetation structure below 50 cm and regeneration age.On mid‐seral stages after sand miningP. novaehollandiaeis associated with areas having a variety of heath plants, with vegetation cover below 50 cm and softer substrates; its abundance increases with increasing regeneration age and with the total amount of vegetation present.A minimum of 20 years is seen to be necessary for both total amount of vegetation andP. novaehollandiaebiomass to reach values encountered on control plots of undisturbe

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1978.tb01191.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractWhereas populations ofEpiphyas postvittana(Walker), the light‐brown apple moth (LBAM), normally produced a slight preponderance of male adults in laboratory cultures, males tended consistently to be less abundant than females in samples drawn from Australian field populations. The sex ratio of the species was investigated with a view to explaining this fact.A condition, causing bisexually‐reproducing females of LBAM to form viable progenies comprising mainly female individuals, was found to affect 7% of females in population samples from the south‐eastern mainland of Australia, and 4% from Tasmania. A statistical model describing the distribution of the condition in field populations is given.The origin of the condition is unknown; the causative agent is believed to act by inducing the death of male embryos. The condition was only observed to be transmitted from mothers to daughters, of which some might produce apparently normal progenies, while others produced either all‐female or predominantly‐female progenies. The demographic performance of affected females differed from that of comparable ‘normal’ individuals only in fertility, which was significantly reduced. In a limited number of experiments, laboratory populations formed from field‐collected samples containing affected females, which produced a proportion of males, could only be maintained through subsidies of males from non‐affected stock.The present case was considered in relation to literature reports of similar conditions affecting a dipteron, a coleopteron, and a macrolepidopteron. InE. postvittana,it is surmised that the condition might contribute to optimizing the sex ratio of populations comprising affected individuals, thus increasing their adaptive fitness. A set of verifiable hypotheses are formulated concerning future trends in the condition's natural distribut

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1978.tb01192.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

The impact and management of birds on the Ord River Development in Western Australia R. J. S. BeetonInvestigations of salinity tolerance in variants of a salt marsh species A. R. Smith‐Whi

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1978.tb01193.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY