摘要:

AbstractFlowering phenology and seed set characteristics of five species ofBanksiawere studied in relation to the nectarivorous birds which feed at their inflorescences. Within the Banksia woodland at the study site near Perth, the flowering seasons of theBanksiaspecies were sequential and only slightly overlapping, providing a year‐round nectar source. Although honeyeaters visited alt five species, seed set was very low in each case. Caging experiments indicated that, inB. attenuataat least, alternative pollinators may play a more important role in pollination than do nectar‐feeding birds. It is suggested that non‐avian pollinators, predatory insects, and characteristics of the breeding system may also have been important in the evolution of the observed flowering phenology and patterns of see

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1980.tb01225.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

AbstractPost‐fire species changes were documented over a portion of the northern section of the jarrah forest of Western Australia from a series of sites of known age since last fire. Species richness and species diversity were observed to increase following fire for several years, followed by a gradual decline. Dominance‐diversity curves indicated that maximum diversity occurred from 3 to 5 years following fire. The species composition of sites of different regions was more similar than sites of similar time since burn. The significance of the results to the programme of controlled burns is discus

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1980.tb01226.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

AbstractPrevious studies relating to the effects of fire on nutrient cycling in Australian native forests are reviewed. It is apparent that: (a) the action of fire on soil fertility is likely to be important in affecting the functioning of Australian plant communities, (b) work to date only gives a guide as to the nature and magnitude of the effects of fire on some nutrient pools and nutrient cycling processes, but has not established the significance of such effects to the nutrient budget of entire forest systems, or established the links between fire, soil fertility and the functioning of forest communities.The difficulties associated with studying and predicting the long‐term effects of fire on the fertility of forest soils are discussed. A new methodology applicable to study of the interaction between fire and plant nutrition is advocated, and is based on examination of the effects of fire on nutrient stores and flux rates in the soil‐litter compartment of the forest. This approach emphasizes the use of changes in rates of nutrient cycling processes as an index of the‐effects of disturbances such as fire on a forest ecosystem. The application of the methodology in a study of the effects of repeated low‐intensity prescribed burning on soil fertility is discussed

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1980.tb01227.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

AbstractThree sites in a Eucalyptus populnea woodland in central New South Wales were sampled for the number and composition of seed in the surface cm of soil. There was a total of 3200 seeds/m2beneath eucalypt canopy, 13800 seeds/m2in grassy inter‐tree areas and 4000 seeds/m2in bare inter‐tree areas in April, 1975. These numbers were reduced by 23, 73 and 66% respectively during the subsequent 10 months, when there was no addition of seed. This decline was thought to be mainly due to predation, with germination as a secondary factor. Species composition of the seed pool differed between the three sites with seed of some species being only found beneath the eucalypt canopy or in the inter‐tree areas. There were no seeds that were not present as plants in the community. Any attempts to restore this woodland to its former grassy nature should take into account the low seed population of many of the formerly common grass species and the high number of shrub seeds (>200/m2). Species distribution of seed was highly heterogeneous making adequate sampling very difficult. Extracting and identifying the seed took 8 to 12 man‐h per 100 g

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1980.tb01228.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

AbstractTotal phenols and condensed tannins in leaves of seven species of Eucalyptus ranged from 4–40% and 0–27% respectively of the leaf dry weight. The concentrations of these compounds were variable but usually high in young and older leaves throughout the growing season, and typically increased during winter, but no other trends with season or leafage were apparent. This pattern of seasonal variation in concentrations of total phenols and condensed tannins is different to that studied for other plant species. This difference may be related to repeated production of new leaves by Eucalyptus during the growing season, and the probability that these leaves will be attacked by herbivorous inse

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1980.tb01229.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

AbstractThe article describes the first step in the formalization of the theory of animal ecology developed by H.G. Andrewartha, L.C. Birch, T.O. Browning, D.A. Maelzer and their students. The classification of the environment given by H.G. Andrewartha inIntroduction to the Study of Animal Populations(1971) is formalized, with the exclusion of the component ‘weather’. In addition, the notion due to D. A. Maelzer that certain objects ‘only modified the value of some resource or other component of environment’ is also formalized and extended. The class of malentities is enlarged to include the case of an animal eating a poisonous animal. This enlarged class includes some animals formally classified as ‘aggressors’. Symbiosis is als

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1980.tb01230.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

AbstractBudgerigars range and breed over most of the interior of Australia. During a year, budgerigars may experience a maximal change in day length of about 5 h, and temperatures range from well below to above their zone of thermo‐neutrality. In the north of the budgerigar's range there is growth of pastures in summer and autumn and in the south there is growth in spring and early summer. In the arid interior, growth is irregular from year‐to‐year and varies from site‐to‐site. However, in northern arid regions growth tends to occur in summer and autumn; in southern arid regions in spring and early summer; and over most of the arid regions in most years there is some growth in run‐on areas.In inland mid‐eastern Australia budgerigars ate only seeds of ground vegetation. These seeds were from about 0.5 to 2.5 mm in length, weighed between about 0.3 and 1.3 mg and had an energy content of about 18.9 kJ g‐1. Ata site on Mitchell grass plains Astrebla spp. were the main seeds eaten. At a site further inland the diet was more diverse: in the hot months of 1973–74 they ate mainlyBoerhavia diffusa, Atriplexspp. andAstrebla pectinata, during the cold months of 1974 mainlyIseilemaand an unidentified seed, and in spring 1974 mainlyAtriplexspp. There was no evidence of special dietary requirements for breeding; in particular no requirements of soft, unripened seed or insect food to feed young. Males and females, adults and juveniles, and individuals in the same flock had similar diets.Information from the literature and my data suggest there is considerable stability and seasonal regularity in the budgeri

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1980.tb01231.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

AbstractA population study of the light‐brown apple moth (LBAM),Epiphyas postvittana(Walker), was pursued from 1963–64 to 1966–67 in a naturally‐infested, unsprayed apple plantation near Canberra. The investigation covered the period of tree development leading up to and including, the production of the first substantial crop.The life history of LBAM and the occurrence of natural enemies were examined. The species did not produce seasonal series of identifiable generations, but individuals in all development stages tended to co‐exist as cohorts of uncertain generation status.Whereas numbers of LBAM decreased gradually from 1963–64 to 1965–66, they rose again markedly in 1966–67, following the release in the study area of about 3,000 laboratory‐reared moths. From periodic field surveys and complementary experiments, it was inferred that the population dynamics of LBAM in the study area consisted essentially in the production of excessive numbers of immature stages, which were reduced by natural enemies to much smaller cohorts of mature stages, determined by the ability of fruit trees to supply the LBAM's requisite food and shelter. It is argued that this ability, i.e. the carrying capacity for LBAM, decreased as the trees matured, and that the damage of LBAM in the crops of fully‐bearing trees would have been negligible under the conditions prevailing in the study area.The probability of damage to fruits was directly proportional to the numbers of larvae and of fruits present, indicating that, unlike codling moth for instance, LBAM did not seek out fruits for attack, but struck them by chance encounter.The results of this life‐system analysis are discussed in the light of Southwood&Comins’(1976) and Southwood's (1977a, b) generalizations on population dynamics, ecological strategies, and the status of pests. LBAM is believed to display all the characteristic features of an ‘intermediate strategist’

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1980.tb01232.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

AbstractSeveral different intertime dissimilarity measures, used with a variety of standardisations of data, were applied to transformed data of macrobenthic species at six sites. These data were obtained over twenty‐two times at 8‐week intervals. Results were evaluated by stepwise regressions (linear, annual cyclical, longer term cycles). Manhattan metric flux between consecutive times was preferred for most subsequent purposes. This flux divided into positive and negative components which measure, summated over all species, rates of recruitment and depletion. Use of algebraic and absolute sums permits evaluation of an index of homeostasis which measures the counterbalancing of recruitment by some species and depletion by others; this index had a value of ca 0.7.Use of the Manhattan metric with catch standardized data indicated changes of community composition at the (more coastal) Bramble Bay sites with a roughly 3‐yr cycle and at the (more oceanic) Middle Banks sites with a roughly 51/2‐yr cycle.In the main analyses, sites were considered individually and in various groupings. It was shown that at Bramble Bay the optimum near‐annual periodicity gives a 50‐instead of a 52‐week year, and also that with increased numbers of sites in a grouping, the greater the significance of the near‐annual cycles.An hypothesis is outlined involving ‘counterbalancing’ between sites of depletion rates due to mobile predators or ‘disturbers’ (fish and prawns). The counterbalancing of recruitment rates is linked to depletion, and is in line with Caswell's (1978) somewhat theoretical paper in which he suggested the temporary action of predation opens up new cells for colonization.This hypothesis goes far towards ‘explaining’ the known patchiness of benthos in Moreton Bay. Also if mobile predators are a link between areas in proximity with different biotas the ecological unit (2 ‘commun

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1980.tb01233.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

The ecology ofRattus lutreolus lutreolus(Gray) on Nadgee River Flat Daniel LunneyLichens on mangroves along the east coast of Australia G. Nell StevensThe ecology and evolution ofRattus lutreolusRichard W. Braithwaite

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1980.tb01234.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY