摘要:

AbstractRemote photo‐monitoring ofBanksia spinulosainflorescences indicated that birds, mammals and insects were regular visitors. These included the sugar glider, brown antechinus, eastern pygmy possum, eastern spinebill, honeybee and several moth species. Eastern spine‐bills were recorded at all inflorescences monitored while visitation by other animals was more sporadic. Inflorescences were visited at least once every 24 h, and visitation frequency was approximately evenly distributed during the day and night. Examination of pollen tube growth from experimental treatments indicated that pollination success was similar from both nocturnal and diurnal visitors. However, nocturnal visitors were more effective at removing pollen from newly opened flowers. The behaviour of mammals at inflorescences was such that they would transfer much more pollen to flowers than other visitors, and probably contact receptive stigmas more often. Overall, mammals were considered to be slightly more effective pollinators than the more obvious daytime visitors, eastern spinebills. Although insects visited regularly, they were thought to be less effective at pollinating flowers than vertebrate visitors. Moths carried very little pollen, and the foraging behaviour of other insects was unlikely to promote much pollinat

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1993.tb00453.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractNew Holland (Phylidonyris novaehollandiae) and White‐cheeked (Phylidonyris nigra) Honeyeaters that are resident in heathland during February and March, when there is negligible nectar production in that habitat, are expected to forage for nectar at that time in the adjacent open forest habitat. As nectar production in the heathland increases from then to June, while that in the forest decreases, the proportion of time spent by these birds in the forest should decrease over the same period. Radiotracking revealed that during February the residents did, as expected, spend time feeding on nectar in the forest and more time was spent in the forest in February than in April or June. However, the residents spent time away from the heathland throughout the year and spent more time away in June than in April. The resident honeyeaters spent about 80% of their time on our heathland grid overall. Radiotracking also indicated that there was no sharp distinction in behaviour between residents and other birds because birds that had been resident in the past but were not considered to be so at the time (absent residents), birds that would later be considered resident (future residents) and some birds that were never resident, all spent about half their time on the grid. The area that included 90% of heathland locations, estimated by radiotracking, forP. novaehollandiaeandP. nigraaveraged 0.48 ha per bir

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1993.tb00454.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractSeeds of four Western Australian accessions ofEmex australiswere stored outside and their germinability tested at 4–6 week intervals for 22 months. Accessions showed cyclical behaviour in germinability, with peaks in autumn/early winter and troughs in spring/summer. There was considerable variation between accessions in dormancy/non‐dormancy cycles, but when plants from accessions with contrasting cycles were grown in a common environment, the cycles shown by their seeds were virtually identical. Thus, the parameters of seed dormancy/non‐dormancy cycles inE. australisappear to be under environmental control.Only part of anE. australisseed population demonstrated cyclical changes in dormancy status, in contrast to many other annual species whose entire seed populations undergo such changes. Populations also contained individuals which were either continuously dormant or continuously non‐dormant following a period of after‐ripening. The latter seeds giveE. australisthe flexibility to recruit opportunistically after summer rainfall events in mediterranean‐climate e

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1993.tb00455.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractDiurnal and seasonal water relations were measured in selected species of aBanksiawoodland at a site with groundwater at a depth of 6–7 m. The canopy co‐dominantsBanksia attenuataandBanksia menziesiiexhibited similar patterns of variation in water relations, both diurnally and seasonally. Stomatal conductance was usually 0.4–0.5 cm s−1diurnally and seasonally and, generally, did not respond to water deficit and other factors. Transpiration was correlated positively with factors indicative of atmospheric evaporative demand, especially total global radiation and pan evaporation, and was highest in summer when canopy water use reached 2.1 mm d−1. Xylem pressure potential at dawn averaged −0.25 MPa in both species throughout the year. Minimum xylem pressure potential varied seasonally and was negatively correlated with transpiration. Seasonal means of minimum xylem pressure potential varied from −1.0 MPa in winter to −1.5 MPa in early summer. BothBanksiaspecies appeared to function as phreatophytes, utilizing groundwater which enabled them to maintain high rates of water use in late summer. Water use over a 12 month period totalled 635 mm, of which the canopy and understorey contributed 61% and 39%, respectively. Water use in the woodland was dominated by the canopy in late summer and the understorey

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1993.tb00456.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractDiurnal and seasonal water relations were measured in understorey species from aBanksiawoodland. The shrubs exhibited various responses to summer drought.Stirlingia latifoliahad high xylem pressure potential and transpiration in late summer.Adenanthos cygnorummaintained high xylem pressure potential year round with dawn values around − 0.3 MPa and minimum values around −1.3 MPa, but showed severe restriction of transpiration in late summer.Eremaea paucifloraandJacksonia floribundahad high transpiration and xylem pressure potential levels in early summer, but exhibited water stress in late summer when transpiration rates were low and minimum xylem pressure potentials were as low as − 5.5 MPa. Late summer xylem pressure potentials in 27 other shrub species were, in general, inversely related to root system depth with minimum values below − 5.0 MPa in some species. The water relations ofS. latifolia, E. paucifloraandJ. floribundaindicated a phreatophytic habit: all possessed deep roots of sufficient size to reach groundwater that was located 6–7 m deep at the study site.Stirlingia latifoliafunctioned phreatophytically year round, whileE. paucifloraandJ. floribundawere phreatophytes until the falling water table carried ground‐water beyond the reach of their roots in late summer. However, most understorey species depended on soil‐stored water. Water use by the understorey was greatest in

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1993.tb00457.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractThe upper and lower limits of the distribution of matureAvicennia marinalie between mean high water and mean sea level in open estuaries in southeastern Australia. Newly established seedlings are highly variable in abundance, but are rarely found in the saltmarsh or on mudflats. Their distribution is unlikely to be limited by dispersal because propagules disperse into the saltmarsh and to intertidal mudflats, but their establishment may be limited by physicochemical conditions, interspecific competition and predation.The model that physicochemical conditions control the intertidal limits of establishment of seedlings was accepted for propagules stranding in the saltmarsh but rejected for those stranding on mudflats. No seedlings established on saltmarsh sediments but similar numbers of seedlings established within light gaps in adult mangrove stands and on intertidal mudflats. The model that interspecific interaction with freeliving macroalgae (Hormosira banksii) reduces the establishment of seedlings on mudflats covered with macroalgae or in stands with a ground cover of macroalgae was accepted. Under controlled conditions five times as many propagules established on cleared ground compared with ground covered with macroalgae. Predators also reduce seedling establishment, but the model that they preferentially act on propagules stranding on the mudflat was rejected. The low number of seedlings found on mudflats without macroalgae appears to relate to wave and current effects on establishment and the effects of waterlogging or fouling on survival.

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1993.tb00458.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractWithin a 50 × 50 m area of wandooEucalyptus capillosawoodland in the Western Australian wheatbelt, the diversity and frequency of occurrence of wood‐eating termite species was assessed at two food types. Over a 12 month period, monthly termite activity was determined: (i) at sound/undecayed artificial baits (seasoned wooden stakes of Jarrah, Karri, Pine, Batu, Oregon; Jarrah sawdust; paper rolls); and (li) at naturally occurring timber, fallen logs and branches of wandoo, in varying stages of decay. Termite diversity was 11 species at baits, 18 species at wandoo out of an overall site richness of 21 species. Karri attracted the most species (9); sawdust attracted none. At wandoo,Nasutitermes exitiosus, Coptotermes acinaciformisandOccasitermes occasusaccounted for 59% of samples where termites were recorded. At baits, Heterotermes occiduus accounted for a mean of 80% of samples across bait types, but was rarely sampled at wandoo (5% of samples). OnlyH. occiduus, C. acinaciformisandAmitermes neogermanusate bait. Pine, Oregon and paper rolls were most effective in attracting foraging termites in terms of highest per cent of replicates showing bait consumption and highest consumption rates. Jarrah and Batu were least attractive to foraging termites. Samples from wandoo underestimated the relative frequency of occurrence ofH. occiduuswithin the study site.Coptotermes acinaciformis, which attack large food items, and certain species ofAmitermes, which forage on subterranean food, may have been underestimated by both sampling methods. These findings indicate that a proper understanding of the structure of wood‐eating termite assemblages within a given area requires a composite sampling strategy which addresses termites that eat sound or decayed wood, as well as surface and subsurface fora

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1993.tb00459.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractWe examined relations between vegetation and soils, using multivariate methods, in hitherto poorly‐known upland swamps on the Woronora Plateau, south of Sydney. A major trend in floristic composition was related to the height and cover of the herbaceous stratum and reflected a gradient in soil moisture and nutrients. A second trend in floristic composition was related to the height and cover of the shrub stratum, and may reflect the influence of recurring fires on certain dominant shrub species. Five plant communities were recognized on the basis of floristic composition and were distinguishable by their different soil habitats and/or structural characteristics. We report some of the highest species‐richness values in the world (at scales of 1–15 m2) for shrub/sedge‐dominated vegetation, with up to 70 vascular plant species in 15 m2. Variation in species richness is inversely related to the resource gradient and positively related to the penetration of light through the vegetation canopy. This pattern is consistent with resource‐competition models and warrants further inve

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1993.tb00460.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractRegeneration patterns ofEucalyptus coolabahBlakely&Jacobs subsp.arida(Blakely) L. Johnson&K. Hill (coolibah), a riparian tree of inland Australia, were inferred from size classes at two locations in South Australia; part of the floodplain of Cooper Creek and a swale in the Strzelecki Desert. These had contrasting water regimes; Cooper Creek floods on average once every 5–6 years whereas the swale has a continual water supply from a bore. A peak in size class distribution showed a regeneration event at each location but at different times. The one in the swale was more recent and was dated to the mid‐1970s using aerial photography. Young (<5 m tall) trees, interpreted as recent regeneration, were concentrated on specific topographic features, the top of a steep riverbank and a sand mound separate from the main dune system. Access to these features would have been difficult after flooding suggesting regeneration is dependent on protection from introduced herbivores. Field observations of reproductive status and canopy die‐back showed coolibah condition was better in the swale. The relatively poorer condition of floodplain coolibahs was attributed to saline soils compounded by drier conditions rather tha

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1993.tb00461.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractA late Quaternary environmental record is currently being developed from Egg Lagoon, King Island, Bass Strait, a site which is geographically well situated to contribute towards a history of the Bass Strait region. Environmental reconstructions are based on a stratigraphic survey and pollen, charcoal and mollusc analyses of sediment core samples. The recorded stratigraphy includes five sedimentary units representing estuarine‐marine, freshwater lake and swamp depositional environments. Amino‐acid racemization analyses of marine shells indicate a greater than last interglacial age for the basal estuarine‐marine unit, while radiocarbon analyses of organic muds and wood suggest that a substantial section of the overlying freshwater lake and swamp facies is beyond the conventional limit for this technique. Local pollen assemblages represent freshwater lake and swamp plant communities that have varied presumably according to water level changes at the site. Regional pollen assemblages represent terrestrial herbaceous communities, believed to have existed under cooler and drier climates than today, andEucalyptus‐ andPhyllocladus‐dom'maied forests and woodlands from periods with greater effective precipitation than at present. A sustained increase in charcoal representation dating from at least 39 000 years before the present may indicate an anthro‐pogenically induced change in the fire regime, consistent with the earliest dates for human occupation in mainla

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1993.tb00462.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY