摘要:

AbstractThe nutrient loads contained in the grassy fuel before fires, and of ash subsequently, were compared to determine the fluxes of macronutrients, copper and zinc during fires at Kapalga in Kakadu National Park. The fluxes were estimated in three vegetation types: forest, woodland and open woodland. The magnitudes of the fluxes were greatest in the forest community where grassy fuel loads were highest at about 6.3 t ha−1. In these sites, 54–94% of all measured nutrients in the fuel were transferred to the atmosphere during the fires. For each nutrient, the proportion transferred to the atmosphere as entrained ash was calculated by assuming that calcium was not volatilized during the fires. If the transfer of entrained ash represents local redistribution only, then rainfall accession and the deposition of these particu‐lates should replace most of the losses of all nutrients except nitrogen (N). Estimated rates of biological fixation of N appear to be insufficient to replace the annual losses of N. It is therefore concluded that a regime of annual fires that completely burn the available grassy fuel would deplete N reserves in these savannas, unless there are other sources of biologically fixed N, which are unknown at pr

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1994.tb00501.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractThis study investigates the importance of climate as a factor influencing the southern distributional limit of the common blossom bat (Syconycteris australis). Using the climatic predictive model BIOCLIM and 73 locality records, 5. australis was predicted to have a coastal distribution in eastern Australia, where winter temperatures are relatively warm and moist conditions prevail throughout the year. The actual southern limit ofS. australis, determined by mist‐netting suitable habitats, was found to be at Booti‐Booti (32°19'S 152°3l'E) on the mid‐north coast of New South Wales. BIOCLIM predicted the southerly limit of 5. australis to be 150–200km further south of their actual limit. Booti‐Booti was occupied at relatively low levels of abundance year round, while the abundance ofS. australisat a site 50 km to the north was much greater, fluctuating with changes inBanksiaflower numbers. Seasonal range extensions beyond Booti‐Booti were not detected, despite the availability of apparently suitable habitat at Myall Lakes only 20–35 km further south. Metabolic costs ofS. australisat Booti‐Booti were estimated to exceed basal metabolic rate (BMR) by 4.5 times, well above the physiologically predicted limit of 2.5 times BMR. These results, together with the lack of range extensions and the close correspondence of BIOCLIM'S predicted southern limit ofS. australiswith their actual limit, suggest that the bat's southern distribution is limited by cold, wet winter

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1994.tb00502.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractWe reviewed the literature on the practice of reservation in Australia over the past few decades. We found that reserves have generally been dedicated for expedient or opportunistic reasons and that they tend to protect the environments with least potential for commercial land uses.Ad hocreservation has two main disadvantages: the environments most in need of strict reservation are not effectively protected; and natural diversity is represented inefficiently in terms of features per unit reserve area. We demonstrate the second disadvantage with quantitative comparisons of alternative reservation scenarios in the Western Division of New South Wales. These show that a continuation ofad hocacquisition of reserves will continue to increase the land area needed to represent all natural environments and so reduce the likelihood of achieving a representative reserve system.

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1994.tb00503.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractAtypichthys strigatus(Günther) were abundant on temperate reefs in New South Wales, Australia. Dietary analyses indicated that they feed primarily on plankton, but also consume benthic organisms. Initial observations suggested thaiA. strigatusrespond to disturbances of the substratum for the purpose of feeding. The substratum in barrens and kelp habitats was experimentally disturbed to examine the response byA. strigatus. Significantly moreA. strigatuswere found in disturbed areas than in undisturbed areas and their feeding rate was greater in disturbed areas. The response byA. strigatusto disturbance was the same in barrens and kelp habitats, although there was a more marked response in the barrens habitat.Atypichthys strigatusalso responded to natural disturbance by large reef fishes (e.g.Achoerodus viridis: Labridae). Furthermore,A. strigatusof a broad range of sizes (25–90 mm standard length) were observed cleaning other reef fishes. The behavioural flexibility ofA. strigatusprobably leads to increased feeding opportunities, and hence increased foraging success, for the fish. Moreover, it raises questions about the accuracy of partitioning fish species according to one trophic gro

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1994.tb00504.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractThe ecologies of seven desert species of monitor lizards (Varanus), which are very variable in size, are described and compared. Data are reported on abundance, anatomy, behaviour, body temperature relationships, daily activity patterns, diet, growth, habitat and microhabitat, prey size, reproduction, seasonal patterns of activity, sexual dimorphisms, and tracks. As many as six of the seven species occur together in sympatry at one study site. New results reported here are merged with extensive data collected over the past quarter of a century to provide a comprehensive and detailed overview of numerous aspects of the natural history and ecology of the seven species in the Great Victoria Desert. One species of pygmy monitor has evolved large clutch size for unknown reasons. A food web for 40 species of desert lizards is presented. Hutchinsonian ratios of head lengths (larger/smaller) are significantly greater in two observed assemblages of sympatric varanids than in a null model consisting of all possible pairs of species of all Australian varanids. Evolution of body size and the two adaptive radiations ofVaranusin Australia are discussed.

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1994.tb00505.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractColonially nesting birds have been implicated in the destruction of their nest site vegetation, the most likely mechanism being through an overload or imbalance of soil nutrients. The numbers of egrets in coastal New South Wales colonies have increased rapidly in the second half of this century since cattle egrets (Ardeola ibis) were introduced. This species now nests colonially with three native species: great (Egretta alba), intermediate (Egretta intermedia) and little egrets (Egretta garzetta). Thus there is potential for more rapid degradation of the colony site. We measured the levels of phosphorus in surface sediments, and phosphorus and nitrogen in water at eight colony site wetlands, and compared each to four other wetlands in the same region where there were no egret colonies. We conclude that levels of both nutrients were elevated in colony wetlands. The implications of this result for death of colony site vegetation and the conservation of the three native egret species are briefly discussed.

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1994.tb00506.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractThe decline in interglacial importance ofCasuarinaover the late Quaternary across southeastern Australia is documented. Three previously proposed causes for the decline (change in fire regime, change to a wetter climate and competitive exclusion by eucalypts) are shown to be inadequate for explaining the majority of cases. Re‐examination of the evidence shows the decline at most sites occurred synchronously with a rise in groundwater or soil salinization, or both. From a review of biological literature, it is established thatCasuarina stricta, the main species considered to have been affected by the decline, is likely to be disadvantaged by high water tables and saline soils. A link is demonstrated between groundwater salinity and the nodulation status ofCasuarinain Victoria. It is concluded that the late QuaternaryCasuarinadecline was caused by a combination of rising groundwater levels and soil salinization. Soil salinization and groundwater level must therefore be considered as major factors determining vegetation patterns in southeastern Australia through the Quaternary up to the present da

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1994.tb00507.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractThe relationship between the abundance of the common blossom bat (Syconycteris australis), a nectar/pollen specialist, and the availability of its food sources was investigated across nineBanksia integrifoliaheathland sites in coastal New South Wales, Australia. An index of bat abundance was more highly correlated with direct estimates of food density (productive inflorescences) than indirect estimates of food (Banksiatrees and total inflorescences). Furthermore, standing crops of nectar‐energy per hectare were better predictors of bat abundance than pollen‐nitrogen per hectare. Adult male mass did not differ significantly across sites of differing food availability, suggesting that the corresponding increase in bat abundance with food reduces the amount of fat an individual can deposit. Although males and females responded similarly to food, adult numbers were more strongly correlated with food supply and they were more likely to be recaptured than juveniles. Energy requirements of blossom bats exceeded availability in four out of nine sites. Flying foxes were heard feeding in large numbers at the remaining five sites, where energy was superabundant forS. australis. In contrast to the conclusions of previous studies of megabats, these results provide the basis for a prediction that nectar‐energy, rather than pollen‐nitrogen, is the primary limiting factor for populations of the blos

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1994.tb00508.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractAnodopetalum biglandulosumgrows in a variety of habits in Tasmanian rainforest. Forty‐eight stands were classified to produce a typology of growth forms for the species. The species has a fundamentally deterministic growth form and exhibits a variety of responses to canopy disruption. The responses are related to community floristics, forest structure and the disturbance regime. The roles of canopy proliferation and clonal spread were investigated for their ecological significance. In some forestsA. biglandulosummay dominate the regrowth after tree‐fall, resulting in a late successional shift in the forest struct

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1994.tb00509.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractSurveys of nesting sites of feral honey bees (Apis mellifera) and regent parrots (Polytelis anthopeplus) were made in the red gum/black box woodlands of Wyperfeld National Park, Victoria, Australia. Data on tree species and size, and number of hollows were collected from all trees within seven 500 × 100m plots. Nest site characteristics were quantified for both bees and parrots. We found 27 feral honey bee colonies, suggesting a density of 77.1 colonies per km2. The average occupation rate for bees was 1.3% of trees and 0.7% of available hollows. The height, aspect and entrance characteristics of honey bee nests at Wyperfeld were not qualitatively different to those reported elsewhere. We found 15 pairs of nesting regent parrots. Nest sites chosen by these birds overlapped those chosen by honey bees, but 52% of bee nests were in cavities unsuitable for regent parrots. We suggest that honey bee population growth may be limited in the park by a lack of water

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1994.tb00510.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY