摘要:

AbstractThis Address examines the current concerns of ecologists. There is instability in the organization of science at a political level, in funding bodies, and in organizations such as CSIRO and tertiary education institutions. There is less funding for research and development in Australia than in other developed countries, mainly because of poor funding from the private sector, and funds available to the new Australian Research Council are small in relation to applications for support. These factors affect career opportunities for ecologists, although students continue to be attracted to the area.The state of the Australian environment leaves much to be desired, with widespread land degradation (including erosion and salination), deterioration in water quality, and disease in natural ecosystems; many species are endangered, and there is concern about forest management.Widespread environmental problems occur despite the fact that, for more than a century, those concerned with land management have been educated in tertiary institutions. More might be done to equip graduates better for solving Australian problems, for informing the public about methods which can be used to correct environmental degradation, and for disseminating research results more directly to managers. While all scientists should emphasize the importance of basic research, it is argued that more recognition should be given to the application of science to management.Among positive aspect of the present climate are a government commitment to increase numbers in senior school years and in tertiary institutions; entry of graduates into consulting work; use of conservation strategies to enhance interaction between ecology and industry as illustrated by mining, agriculture and forestry; increased activity by organizations which raise funds from the private sector; definition of research priorities; and the identification which Australians have with an image of the countryside.With this framework of closer links between ecology, practical problem‐solving, and support from industry and the private sector, it is argued that significant progress will be made in the years ahea

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1989.tb01003.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractPre‐dispersal seed losses to insects in species ofLeptospermumat Wilson's Promontory in south‐eastern Australia varied markedly between species, seasons, sites and individuals. The proportion of fruits attacked by insects averaged 11% (range 3–37%) in populations ofLeptospermum juniperinum, 23% (6–95%) inLeptospermum myrsinoides, 23% (0–47%) inLeptospermum laevigatum, and 28% (8–45%) inLeptospermum lanigerum. The proportion of seeds lost in attacked fruits also varied widely. Differences between species varied markedly from year to year, but differences between sites were relatively constant. Fruit production byL. myrsinoideswas unusually low at most sites during 1984; in each case this coincided with unusually high rates of insect attack, suggesting that predator satiation operates during nor

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1989.tb01004.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractThe diets of seven of the eight species of insectivorous, vespertilionid bats found in Tasmania were studied in forest areas. The diet of the eighth species,Chalinolobus gouldii, was studied in riparian woodland surrounded by open pasture.Nyctophilus timoriensiswas found to be a gleaner with most of its diet consisting of non‐volant insects. Five of the species (Eptesicus vulturnus, Eptesicus regulus, Eptesicus sagittula, Nyctophilus geoffroyiandChalinolobus morio) fed opportunistically, their diets reflecting local and temporal variations in insect abundance and diversity. Lepidoptera made up most of the diet of these species. The largest species,Falsistrellus tasmaniensis, appeared to be a selective feeder, with Coleoptera being the most important item in its diet. Coleoptera also made up the bulk of the diet of C.gouldii, but caterpillars were also important. For the species studied in forest areas, there was a highly significant correlation between the mean sizes of the lepidopterans (r= 0.95) and coleopterans (r = 0.96) eaten and the size of the bat. For all bats larger thanE. sagittula, the mean size of beetles eaten was smaller than the mean size of moths eaten. These results are in accord with expectations from optimal foraging theor

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1989.tb01005.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractSeasonal changes in the abundances of five species of honey‐eaters were assessed in relation to the flowering phenology of Banksia menziesii in banksia woodland near Perth, Western Australia. The total number of honeyeaters was significantly correlated to the number of inflorescences ofB. menziesii. New Holland Honeyeaters. Brown Honeyeaters and Western Spinebills were present throughout the year, whereas the larger honeyeaters (Red and Little Wattlebirds) were observed when B. menziesii was flowering.The foraging behaviours of the Little Wattlebirds, New Holland Honeyeaters, Brown Honeyeaters and Western Spinebills were similar and all were likely to effect pollination of B. menziesii florets. Differences in their foraging position at an inflorescence, number and direction of foraging probes, and the time spent at an inflorescence were minimal. Western Spinebills used inflorescences lower in the tree crown than the other species. Movements to inflorescences on different plants were inversely related to honeyeater size. Smaller honeyeaters were frequently chased from inflorescences by the larger species, increasing the proportion of distant foraging movements made by the smaller species. Also these interrupted visits were of shorter duration than uninterrupted visits. Visitation by smaller species, especially the Brown Honeyeater, may result in more cross pollinations although the effect on the reproductive success of B, menziesii is unknow

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1989.tb01006.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractThe bird community of a forested 13 ha plot was studied for 3 years, during which the plot was burnt by wildfire and was severely drought‐affected. The combined effects of fire and drought were surprisingly limited. Similar numbers of species were recorded in each year and differences in species composition involved only rare visitors to the plot. Colour‐banding indicated population declines in at least six resident species. The greatest decline was that of the Brown Thornbill (Acanthiza pusilla), from 20 pairs to 10 pairs. In general, insectivorous birds were most abundant and widespread on the plot during the first year, before the fire. In contrast, nomadic birds feeding on flowers or fruits were most abundant in the second year, when there was a prolific flowering and fruiting of several important food plants. After the fire, at least ten bird species avoided the burnt ridges and became more concentrated in the unburnt gullies. Most were species associated with dense shrub thickets, the layer of vegetation most affected by the fire. It seems that gullies are major refuge areas in these forests and are the key to the resilience of the bird community to fire and drou

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1989.tb01007.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractMovement in the soil of seeds of the invasive shrubChrysanthemoides moniliferawas studied in relation to the success of proposed biological control treatments. Marked seeds were buried at depths from 0 to 6 cm and recovered after periods of 3–24 months. Survival declined with time but was higher for more deeply buried seeds. The average movement of seeds was 0.7 cm per year downwards which enhances their survival but also tends to remove them from the zone of highest likelihood of germination.A model was constructed to predict the size of the pool of potentially germinable seed under treatments including pre‐dispersal predation and burning. It indicated that satisfactory control with a pre‐dispersal seed predator will be achieved only if there is a90% for a part of the year (e.g. during winter when seed‐fall is abundant). The effectiveness of the control could be enhanced by using intense fires to reduce the soil seed‐pool and to kill many of the mature shrubs. However, the feasibility of this combination of treatments will depend on the reaction of the biological control ag

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1989.tb01008.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractThe horizontal spatial patterns of heath species have implications in dynamic community modelling, fire behaviour modelling and ecological interpretation. The distribution pattern of the dominant woody species in a subalpine heath woodland near Kiandra, New South Wales was analysed as spatial point processes. The species analysed wereBossiaea foliosa, Grevillea australis, Hakea lissosperma and Oxylobium ellipticum, and both large (>2m) and small (<2 m) snowgums(Eucalyptus pauciflora)They all exhibited significant aggregation at scales ranging from 1 to 15 m. Bivariate spatial analyses of these species revealed significant negative association betweenG. australis and H. lissosperma, between G. australis and O. ellipticum, and between O. ellipticum and H. lissosperma, B. foliosawas independently distributed with respect to other shrub species. There was some evidence for negative association between small snowgums and shrub species, though small snowgums were positively associated with large snowgums. The joint spatial distribution of the individuals of all shrub species was also aggregated. A Poisson cluster process was developed and tested to model the joint spatial pattern of the shrub stratum.

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1989.tb01009.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractThis study measured the quantities of effective pollen vectors and their pollen loads arriving at the canopies of dioecious tropical rain forest trees in north‐east Queensland. Population flowering synchrony, effective pollinator populations and pollen loads transferred between staminate and pistillate trees were compared among three insect‐pollinated tree species. All three were visited by a wide range of insects, 75% of which (mostly 3–6 mm long) carried conspecific pollen. Fewer than 8% of individual insects were found to be carrying single‐species pollen exclusively and none could be described as specialist pollen foragers. The introduced honeybee carried greater quantities of pollen than any native species but was not necessarily a reliable pollinator.The brief flowering periods inNeolitsea dealbata(3–4 weeks) andLitsea leefeana(4–5 weeks) populations were synchronized among individuals. Flowering in theDiospyros pentamerapopulation extended over 15 weeks and most individuals were in flower for most of this period. Staminate trees began flowering earlier, produced more flowers and attracted relatively more insects than did pistillate trees, suggesting a density‐dependent response of pollinators to flowering performance. Pollen was trapped in greater quantities on insects at staminate trees than at pistillate trees.Insect numbers increased at peak flowering periods and Diptera were the most abundant flower visitors. Anthophilous Coleoptera were more numerous at staminate than at pistillate trees in all three tree species populations. Larger quantities of pollen were mobilized during peak flowering times although the greatest quantities were transferred to pistillate canopies towards the end of the population flowering periods. Diptera carried pollen more often to pistillateN. dealbataandL. leefeanatrees than did other groups whereas Coleoptera carried pollen more often to pistillateD. pentameratrees. The two contrasting flowering performances in the three tree species are discussed with reference to mechanisms that facilitate pollen transfer between staminate and pis

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1989.tb01010.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractAn analysis of the pyrrolizidine alkaloids (PA) of the introduced annual weed,Heliotropium europaeum(Boraginaceae), at two sites in south‐eastern Australia showed that percentage PA in above‐ground parts of the weed differed significantly between sites and declined markedly through the season, from initial levels of>2.2% in the seedling stage to95% of total alkaloid. Major PA constituents — europine, heliotrine, and lasiocarpine — varied significantly between sites and sampling dates but no marked seasonal trend was detected. Lasiocarpine and europine content varied reciprocally in the free base andN‐oxide forms, indicating that these compounds may be readily interconvertible. Correlation of rainfall and average number of leaves per plant with lasiocarpine and europine levels suggested that rainfall, either directly by altering the metabolism of existing leaves or indirectly through plant growth, initiated large short‐term shifts in PA composition ofH. europaeumwithout corresponding changes in total PA concentration.At both sites, sheep consumedH. europaeum, reducing both plant density and biomass. Biomass differences between exclosure and access plots ofH. europaeumwere correlated with grazing intensity. Since heliotrine, lasiocarpine and europine differ markedly in their toxic properties, large shifts in their relative concentrations may have important consequences for these and other herbivores. Environmentally induced quality shifts in these secondary compounds may be as important as, or even override, changes in total quantity in causing PA toxicity to gr

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1989.tb01011.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractTemperature requirements for follicle rupture were assessed in 10Banksiaspecies from south‐western Australia. Species examined varied in degree of serotiny, persistence of dead florets, height, follicle size and number, and dependence on seed for regeneration.When treated for 2 min at temperatures over the range 100–500°C, follicles of some species ruptured at quite low temperatures (e.g.Banksia tricuspiswith 50% opening at 145°C). Others required substantially higher temperatures (e.g. Banksia hookeriana with 50% opening at 390°C). There was a significant correlation between temperature requirements for follicle rupture and persistence of the highly combustible florets. However, there was no overall correlation between degree of serotiny and temperature requirements, nor with the other biological attributes assessed.Cone temperatures and follicle rupture in five co‐occurringBanksiaspecies were monitored for an experimental spring burn inBanksia‐dominated shrubland. Temperatures recorded at follicle surfaces were higher than those needed for follicle rupture in the four species with persistent florets. Critical temperatures were rarely reached for the weakly serotinousBanksia menziesiiwhich possesses bare cones and an o

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1989.tb01012.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY