bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bills and tongues of nectar‐feeding birds: A review of morphology, function and performance, with intercontinental comparisons
Authors: PATON D. C. , COLLINS B. G. 
Published: July 2006

AbstractThe bills and tongues of nectar‐feeding birds differ from continent to continent. The major differences are that: (i) the tongues of A Australian honeyeaters are broader any more fimbricated at the tip than the bifurcated tongues of sunbirds and hummingbirds; (ii) the bills of hummingbirds are more uniformly narrow and taper less markedly towards their tips than those of sun‐birds and honeyeaters; and (iii) bill curvatures are generally greater for sunbirds and honey‐creepers than for hummingbirds. A variety of hummingbirds has straight or even slightly upturned bills, while bills for all sunbirds, honeycreepers and honeyeaters are decurved to some extent. Despite differences in tongue morphology, hummingbirds, sunbirds and honeyeaters extract nectar at a similar range of rates, averaging approximately 40 γL s−1 from ad libitum feeders, and 1–15 γL−1 from flowers. All tongues collect nectar by capillarity, with licking rates of 6–17 s−1. Licking behaviour has been little studied, although speeds of licking respond to changes in sugar concentration and corolla length. The tongues of honeyeaters are broad, and may need to be brush‐tipped in order to allow capillary collection of nectar. Brush‐tipped tongues can cover large surface areas on each lick, and may allow honeyeaters to exploit nectar and honeydew that is thinly spread over large surface areas. Bill lengths of nectarivorous birds are similar in all regions, though species of hummingbird have the shortest and longest bills. Bill lengths largely determine the range of floral lengths that can be legitimately probed. Maximum floral lengths exceed bill lengths, since hummingbirds, sunbirds and honeyeaters protrude their tongues beyond the tips of their bills. Rates of nectar extraction, however, decline rapidly once the floral length exceeds bill length. Decurved bills may have evolved in honeyeaters and sunbirds to enable perching birds to reach flowers at the ends of branches more easily. Consistent differences in bill length between the sexes suggest that males and females may exploit different floral resources or different proportions of the same resources. For honeyeaters and sunbirds, males have longer bills than females, but the reverse is true for many hummingbirds.
Effects of multiple disturbance on macroinvertebrate communities in the Acheron River, Victoria
Authors: LAKE P. S. , DOEG T. J. , MARCHANT R. 
Published: July 2006

AbstractIn the Acheron River, southern Victoria, patches of riffle substratum (ca 1 m2) were disturbed every 10 days by kicking and raking. After 20 days, i.e. three disturbances, a further set of patches was disturbed once. For the next 70 days macroinvertebrate dynamics were monitored in the two sets of disturbed patches and also in contiguous control patches. There were no differences in the temporal changes in total species richness, number of species per sample, densities of individuals, or species diversity (H’) between the two disturbance regimes. The composition of the fauna colonizing each disturbance regime was similar, and after 33 days the number of species per sample was similar in disturbed and control patches. The fauna appears to be well adapted to physical disturbance and current ideas linking species richness and disturbance cannot be readily applied to stream communities at the temporal and spatial scales of this experiment.
The size and composition of soil seed‐banks in remnant patches of three structural rainforest types in North Queensland
Authors: HOPKINS M. S. , TRACEY J. G. , GRAHAM A. W. 
Published: July 2006

Abstract The size and species composition of the soil seed‐bank in a remnant patch of each of three structurally and floristically distinct rainforests (Complex Mesophyll Vine Forest, Complex Notophyll Vine Forest and Semi‐Evergreen Vine Thicket) were assessed. Seeds of 94 species germinated from 12 surface soil samples collected from each site. All three seed‐banks were composed mostly of herbs characteristic of roadsides and agricultural land, and pioneer rainforest trees and shrubs. Agglomerative classifications indicated that the seed‐bank samples from each rainforest remnant had a characteristic species composition and could be distinguished reliably from seed‐bank samples drawn from other sites. Seeds of species present in the standing forest were poorly represented in the seed‐banks except for one long‐lived pioneer tree, Dendrocnide photinophylla, at one site. The seed‐bank from the seasonally dry vine thicket was significantly larger (4000 seeds m‐2) than those from the two moister sites (400–600 seeds m‐2, contained more seeds of roadside and agricultural herbs, and fewer seeds of rainforest pioneer and secondary shrubs and trees. We suggest three explanations for the different seed‐bank structure observed in the seasonally dry forest site. First, with increased deciduousness in rainforests, seed‐banks are increasingly subject to invasion and domination by seeds of rapidly maturing herbs. Second, long‐lived seeds that germinate in canopy gaps would be less likely to accumulate under deciduous forests because they would he exposed annually to conditions suitable for germination. Third, chronic disturbance by cattle and pigs produces sites suitable for the establishment of rapidly maturing herbs, and possibly disperses their seeds into the forest.
Dieback of rural eucalypts: the effect of stress on the nutritional quality of foliage
Authors: LANDSBERG JILL 
Published: July 2006

Abstract Canopy dieback of Eucalyptus blakelyi trees is often associated with defoliation by insects: the foliage of trees with dieback is nutritionally superior for insects and is more heavily damaged by them. I investigated whether differences in the nutritional quality of foliage were genetically determined, or caused by environmental stress. In a series of glasshouse experiments, with seedlings and grafted plants derived from dieback and healthy populations of trees. I tested the influence of deprivation of nutrients, drought, waterlogging, saline waterlogging and addition of excess phosphate, on the nutritional quality of foliage. Differences in the foliar properties of plants from different genetic sources were not consistent with the differences between the source populations. Most of the environmental stresses applied caused a reduction in foliar quality (decreased water and nitrogen contents, and increased specific leaf weights). I hypothesize that the enhanced nutritional quality of the foliage of dieback trees is more likely to be a consequence of benign growing conditions (e.g. improved soil fertility) than of environmental stress. Field data for soil properties and the effect of drought on mature trees are consistent with this view.
Seasonal variation in honeyeater foraging behaviour, infloresence abundance and fruit set in Banksia spinulosa (Proteaceae)
Authors: VAUGHTON GLENDA 
Published: July 2006

Abstract Seasonal variation in the foraging behaviour of honeyeaters and the production of fruit were examined in relation to the flowering intensity of Banksia spinulosa over two flowering seasons. The abundance of inflorescences was greater in the mid than in the early and late periods of the flowering season. In the mid period, many plants were blooming and each plant had many flowering inflorescences. Inflorescences received most visits by honeyeaters in the early flowering period; the visitation rate declining as flowering progressed. Eastern spinebills were the most common floral visitors at all times during the season. The number of foraging probes made at inflorescences by eastern spinebills did not differ throughout the season. Foraging movements between inflorescences on the same plant were more frequent in the mid period than in the early and late periods. Long distance movements between plants (more than 10 m apart) were promoted by aggressive interactions between honeyeaters. Inflorescences flowering in the late period were less likely to develop follicles because there were fewer visits by birds and/or because resources had been allocated to inflorescences pollinated earlier in the season. The number of follicles produced per infructescence did not differ between flowering periods. Overall, the number of inflorescences produced per plant, the number of visits received per inflorescence and the proportion of inflorescences that developed follicles were greater in 1987 than in 1988.
The use of open burrows to estimate abundances of intertidal estuarine crabs
Authors: WARREN J. H. 
Published: July 2006

AbstractEstimation of absolute (or true) abundances of intertidal burrowing crabs is a difficult problem in some estuarine habitats because the nature of the substratum and behaviour of crabs can restrict researchers to the use of sampling methods which at best estimate only apparent, or relative, abundances. One method that has been used is to count open burrows to estimate population densities. This paper discusses the results of a test examining the validity of using burrows to estimate apparent abundances of a temperate ocypodid crab, Heloecius cordiformis. inhabiting mangrove forests of south‐eastern Australia. Under appropriate circumstances, this method may provide a quick and reliable estimate of abundance of crabs.
Methods for measuring amounts of energy available from banksia inflorescences
Authors: ARMSTRONG DOUG P. , PATON DAVID C. 
Published: July 2006

AbstractSeveral methods have been used to remove nectar from banksia inflorescences to measure amounts of energy available, but these methods have been poorly described in the literature. Each method has advantages and disadvantages with respect to the proportion of nectar removed and the time taken to remove nectar. Power‐driven aspirators probably remove the most nectar, followed by syringes and capillary tubes. However, it often takes more than 20 min to sample an inflorescence using these methods. Centrifuging inflorescences by placing them in plastic bags and swinging them by hand on a rope takes only about 5 min anil allows many more inflorescences to be sampled per time. Centrifuging. however, removes only about 70% of the nectar so that the benefits gained by faster sampling are countered by reduction in accuracy. Nevertheless, amounts of nectar extracted by centrifuging provide a reliable index of the amounts present, and so it is possible to make Qualitative comparisons of inflorescences sampled at different times, from different locations, or from different experimental treatments.
Linear oceanographic features: A focus for research on recruitment processes
Authors: KINGSFORD M. J. 
Published: July 2006

AbstractThe early life of reef‐associated organisms is generally spent in the plankton. Recent evidence suggests that oceanographic processes have an important influence on the fate of early developmental forms; a surprising number of these manifest themselves as lines at the ocean surface. Lines, or slicks, are convergence zones where organic material collects. Internal waves, Langmuir circulations, topographically controlled fronts, estuarine, coastal and oceanic fronts produce linear or curvi‐linear slicks. The biological importance of these features is discussed. Slicks are ideal for investigating factors influencing meroplankton.
Behavioural variability in marine larvae
Authors: RAIMONDI PETER T. , KEOUGH MICHAEL J. 
Published: July 2006

AbstractDespite increasing recognition of the importance of larval settlement, recent models have concentrated on small and large scale hydrodynamic effects as determinants of larval settlement. Implicit in most of these discussions is the assumption that variability in larval behaviour either does not exist, or is unimportant.We present evidence that this is an inaccurate description of larval behaviour at the time of settlement. There exists considerable variation in behaviour at a number of scales, even under controlled laboratory conditions. For almost all species examined, responses to attractive and discrete stimuli were non‐uniform. The causes of variability in larval behaviour both within and between populations are largely unexplored. We suggest that variable behaviour, in response to discrete stimuli, may be a selectable trait. If so, the manifestation of such variability in individuals within a population is simply the expression of an adaptive trail. By this reasoning, differences in larval behaviour between populations are evidence for varying selective pressures. We conclude with an examination of possible consequences to a population, arising from variable larval behaviour.
The adaptive significance of life history characters in selectedorders of marine brown maeroalgae
Authors: CLAYTON MARGARET N. 
Published: July 2006

AbstractLife history charaeters. which are generally eonsidered to be of eritieal signifteanee in evolution, consist of various pheiiotypie trails eoneerned with growth and reproduetion. Suites ot life history charaeters are frequently referred to as ‘strategies’. These are hypotheses which attempt to explain the adaptive significance of particular suites of charaeters. This paper reviews life history charaeters of species belonging to various orders of brown algae (Phaeophyeeae) and diseusses their possible adaptive, significance, together with the extent to which they are eonsistent with opportunistie, stress tolerant and biotieally eompetent strategies. In general, speeies belonging to the same order have broadly similar suites of life history charaeters and, thus, to some degree they share eomparable adaptive strategies. For example. the Laminariales, Fueales and Durvillaeales inelude a high proportion of biotieally eompetent speeies. many ofthe Dietyotales appear to be stress tolerant, and the Eetoearpales are typieally opportunistie. The two heteromorphie generations of speeies in the Seytosiphonales are viewed as having divergent strategies, the erustose stages showing a greater degree of stress toleranee than the opportunislie ereet stages.
Biogenic habitat structure and characteristics of temperate reef fish assemblages
Authors: HOLBROOK SALLY J. , SCHMITT RUSSELL J. , AMBROSE RICHARD F. 
Published: July 2006

AbstractAssemblages of non‐cryptic, substrate‐oriented species of fish were compared on a series of reefs in Southern California, USA. Reefs were grouped according to algal cover: dense beds of giant kelp (Macrocystis pyrifera) with turf understorey; sparse beds of giant kelp with foliose algae understorey: foliose algae < 1 m in height; and open barrens. Despite affinities to particular algal substrates by many individual species, we detected no differences in fish species richness and only weak differences in species composition among reefs of different habitat types. Planktivores and species that consume macro‐invertebrates were less likely to occur on reefs that supported giant kelp; the frequencies of occurrence of three other trophic groups (piscivores, herbivores and micro‐carnivores) were unaffected by giant kelp.Algal composition on reefs in Southern California is temporally highly dynamic. Changes in macro‐algal composition of reefs influenced population dynamics of two fish species (black surfperch and striped surfperch) examined. Overall, the weak spatial variation in fish assemblages on reefs in Southern California appears to result from relatively unspecialized ecological requirements of many species combined with temporal changes in algal structure on reefs that are rapid relative to generation times of the fish. We hypothesize that the degree of spatial differentiation in assemblages of substrate‐associated species of fish may be inversely related to the temporal constancy of biogenic reef structure.
Resource allocation patterns in Spinifex sericeus R.Br.: A dioecious perennial grass of coastal sand dunes
Authors: MAZE K. M. , WHALLEY R. D. B. 
Published: July 2006

AbstractThe resource allocation patterns within populations of Spinifex sericeus R.Br, were studied on the mid north coast of NSW. Sand burial and nutrient availability were two major factors influencing the allocation of resources to roots, culms, tillers and inflorescences, resulting in different growth forms in different sections of the dune. The data suggest that pollen availability may affect allocation to seeds late in the flowering season.Spinifex sericeus was found to have a greater below‐ than above‐ground biomass, especially on the crest of the incipient foredune where sand accretion was high. The ability of culms of S. sericeus to grow upwards at a rate that generally prevents complete burial of the tillers is one mechanism which allows S. sericeus to vary resource allocation patterns in response to a varying environment.Differences in the inflorescence characteristics of males and females indicate their different functions. The much greater floret number of males indicated the importance of pollen dispersal. Female inflorescences consisted mainly of structures other than florets and suggested the importance of the female inflorescence in seed dispersal.Addition of nitrogen and phosphorus increased the number of spikelets and seeds but not the proportion of spikelets which produced seed.
The ecology of water‐filled treeholes in Australian rainforests: Food web reassembly as a measure of community recovery after disturbance
Authors: JENKINS B. , KITCHING R. L. 
Published: July 2006

AbstractTen water‐filled tree holes in a subtropical rainforest were emptied out thereby imposing a major perturbation on the community of organisms which occupied these habitat units. During the process of food web reassembly following this disturbance, the average number of predator species in the web increased as did the average number of prey species. Predator‐prey ratios increased in magnitude with the number of days after the disturbance. Furthermore, the characteristic mean predator‐prey ratio of the original community was gradually restored as the food web reassembled. The number of prey species was found to be a better predictor of the number of predator species during community recovery than vice versa. The increasing number of trophic links in the food web over the period of reassembly, due mainly to the increase in the number of predacious species in the web, provides a good overall measure of community recovery. The paper discusses the use of relationships among the food web statistics described within a model of food web reassembly. Such a model can be used to assess the rate of recovery of a community after a disturbance of the food web at the regional level of resolution. Further, the question of whether or not the rate of community recovery can be used to estimate ecosystem recovery with the aid of food web statistics is examined.
Soil seed densities and emergence patterns in pastures in the seasonally dry tropics of northeastern Australia
Authors: McIVOR JOHN G. , GARDENER CHRISTOPHER J. 
Published: July 2006

AbstractGerminable seed densities in the surface (0–10 cm) soil of pasture communities growing at Lansdown, near Townsville, were measured during the late dry season before the first germinating rain and again during the following wet season after germination but before the input of new seed. Seedlings emerging in the field were counted at approximately weekly intervals during this period to determine emergence patterns. Twelve communities were sampled in 1980–81 and six were re‐sampled in 1981–82.During the late dry season germinable seed densities ranged from 5000 to 40 000 seeds m‐2. Seeds of the introduced legume, Stylosanthes hamata, were present in all pastures. There were many seeds of annual grasses (Digitaria ciliaris and Brachiaria miliiformis) and sedges (Cyperus and Fimbristylis spp.) but only few seeds of perennial grasses (both native and introduced). Soil seed densities were much lower during the wet season than during the preceding dry season, particularly for the grasses.Emergence commenced and approximately 70% of all seedlings emerged on the first major rainfall of the wet season. The subsequent emergence pattern varied between years. In 1980–81 there was a gradual and continuous increase in seedling numbers under the continuously moist conditions which prevailed. In 1981–82 further emergence occurred in discrete events related to rainfall and intervening dry periods. Maximum seedling densities exceeded 34 000 seedlings m‐2 including 29 000 grass seedlings (mainly annual species).The implications of these results for species survival and pasture composition are discussed.
The ecology ofLagarostrobos franklinii(Hook.f.) Quinn (Podocarpaceae) in Tasmania. 2. Population structure and spatial pattern
Authors: GIBSON N. , BROWN M. J. 
Published: July 2006

AbstractAnalysis of stand structure and spatial patterning indicates thatLagarostrobos franklinii(Huon pine) regenerates intermittently in response to canopy disturbance. Its ability to resprout rapidly from fallen trees is likely to be important in the continued dominance of gaps by this species in competition with faster‐growing tree species. The largely riverine distribution pattern of this species is best explained by rapid vegetative spread down river systems and slow dispersal into canopy gaps away from river edges. The probability of recurrent disturbance within the lifespan of this species is high, implying that competitive exclusion of Huon pine is unlikely once it establishes at a site.
Patterns in shallow subtidal marine assemblages along the coast of New South Wales
Authors: UNDERWOOD A. J. , KINGSFORD M. J. , ANDREW N. L. 
Published: July 2006

AbstractShallow subtidal areas of rocky reefs in central and southern New South Wales may best be described as a mosaic of habitats, the distributions of which are seemingly related to depth, wave exposure and a number of biological processes, particularly herbivory. The Fringe habitat is generally found only in the most shallow waters. Forests of the laminarian alga Ecklonia radiata are often found at intermediate depths. In deeper, or more sheltered water, sponges, ascidians and red algae are more abundant and the abundances of sea urchins and other invertebrate grazers decline. Overlying this broad‐brush pattern are patches of crustose coralline algae (the Barrens habitat), the distributions of which are not clearly related to depth. Invertebrate herbivores, and sea urchins in particular, are abundant in the Barrens habitat. The Barrens habitat was most represented at the more southern locations. At the two most northern locations, reefs were shorter in length and dominated by ascidians (Pyura species).