bluuebunny/crossref_metadata_2025_split huggingface dataset:
Light environments within montane tropical rainforest, Mt Bellenden Ker, North Queensland
Authors: TURTON S. M. 
Published: July 2006

AbstractIrradiance and photosynthetic photon flux density (PPFD) at five sites within a montane tropical rainforest were compared to test for differences among characteristic environments within the same forest type. The five habitats investigated were a large clearing (800 m2). a small gap (150 m2), the lower canopy, and two shaded understorey sites. Daily average irradiance ranged from 32.3 W m‐2 in the heavily shaded understorey to over 400 W m‐2 in the large clearing. Similarly, daily average PPFD ranged from 10.2 to over 800 μmol m‐2 s‐1 at corresponding sites, respectively. Daily total irradiation in the understorey, small gap, and lower canopy were 7.9–8.8%, 11.8% and 11.5%, respectively, of irradiation in the large clearing. For daily total PPFD, relative values for the same sites were 1.3–3.8%, 6.0% and 10.3%, respectively. Comparisons of frequency distributions for irradiance showed that the only significant difference was between the large clearing and the four forest sites. Comparisons of frequency distributions for PPFD showed significant differences among all five sites. Median PPFDs were always above the range of known light compensation points for rainforest plants even in the heavily shaded understorey, and usually above the known light saturation levels of canopy members. These results indicate that the reduction in PPFD by cloud cover does not limit the rates of photosynthesis.
The roles of floristics and physiognomy in avian community composition
Authors: MACNALLY RALPH C. 
Published: July 2006

AbstractThere has been debate as to whether the composition of avifaunas is determined primarily by responses of species to the floristic composition of habitats or to the structural features of habitats (viz. physiognomy). Some evidence suggests that the effects of geographic scale may be the source of this dispute. The present analysis demonstrated that the influence of both floristics and physiognomy could be detected at the regional level for avifaunas of south‐eastern Australian woodlands. The impact of floristics often may be obscured by patchiness and relatively rapid rates of spatial change in the phytosociology of habitats relative to those of avian species, even at the local scale (say 10 km). Such potential occlusion of the importance of floristics to avifaunas may be overcome by using floristic similarity indices that are based on plant taxonomic representations at both the specific and subfamilial levels. Both floristics and physiognomy are likely to affect avifaunal composition, although the perceived significance of each factor may vary with the scale of observation.
Larval predation by epifauna on temperate reefs: scale, power and the scarcity of measurable effects
Authors: YOUNG CRAIG M. 
Published: July 2006

AbstractBenthic suspension feeders often occur at high densities on temperate reefs and other hard bottoms. Beeause many such organisms hayc prodigious feeding rates in the laboratory, it has often been predicted that established epifauna would deplete larval populations, thereby influencing density, spatial distribution and species eomposition at settlement. Most field manipulations of filter‐feeder density have not controlled for faetors other than larval predation that could produce the same pattern. In controlled experiments, larval predation effects are seldom observed. Intermittent feeding and small radii of predator influenee present many more opportunities for settlement than has generally been assumed. Two important faetors often foil attempts to measure predation effeets: low statistieal power due to small effect sizes, and choice of spatial scales larger than thdse where predation effeets oeeur.
Palynology of a Holocene marine transgressive sequence, lower Mulgrave River valley, north‐east Queensland
Authors: CROWLEY G. M. , ANDERSON P. , KERSHAW A. P. , GRINDROD J. 
Published: July 2006

AbstractA sediment core from the lower Mulgrave River flood plain in north‐east Queensland was examined using standard pollen analysis techniques to investigate vegetation and sea level changes during and since the Holocene marine transgression. Saltwater penetrated the Mulgrave River to the core site in the early Holocene, with the consequent development of riverside mangrove forests dominated by Sonneratia lanceolata, a community not previously recorded in Australian pollen sequences. From about 7000 to 6000 years ago, Rhizophora forest was the dominant vegetation community around the site. During this period, vertical sedimentation kept pace with, or at times exceeded, the rate of sea level rise. As sea level stabilized, about 6000 years ago, continued sediment accumulation led to the development of upper‐intertidal Ceriops/Bruguiera forest and then freshwater swamp forest. The vegetation changes in this latter part of the sequence reflect the present seaward to landward vegetation zonation in the area.
Experimental transplants of mice (Pseudomys and Mus) on to early stages of post‐mining regeneration in open forest
Authors: FOX BARRY J. , TWIGG LAURIE E. 
Published: July 2006

AbstractResults are presented for three controlled replicated experiments in which mice were transplanted onto the early successional stages of two regenerating mining paths. Naive house mice (Mus musculus) were successfully introduced on to sites regenerating for 8 years, with 56% remaining after 3 days and 2% still present after 69 days. Naive New Holland mice (Pseudomys novaehollandiae) had marginal establishment success on sites regenerating for 4.9 years, with 21% remaining after 3 days and 3% still present after 22 days. However, on sites regenerating for 3.9 years and 4.4 years, all 17 transplanted New Holland mice had dispersed from the treatment plots after 3 days. New Holland mice have been shown to be competitively dominant to house mice. Hence, we conclude that the reason New Holland mice do not colonize mining paths regenerating for less than 4.9 years is the unsuitability of the habitat rather than their exclusion by house mice. These results are consistent with the early stages of the mammalian succession following sand mining and fit the same habitat accommodation model proposed for post‐fire mammalian succession.
Fish larvae settling in seagrass: Effects of leaf density and an epiphytic alga
Authors: WORTHINGTON D. G. , WESTOBY M. , BELL J. D. 
Published: July 2006

AbstractSettlement of fish to seagrass with low leaf densities was investigated by a field experiment in Botany Bay, NSW. Artificial seagrass units (ASU) were used to simulate isolated seagrass habitats of 0, 25, 50, 100, 200 and 400 leaves m‐2. A total of 369 fish of 21 species settled in the experimental units during a 6 week period. The labrid, Achoerodus viridis, made up almost 70% of these individuals. The abundance of recently settled A. viridis increased greatly between 0 and 25 leaves m ‐2, At more than 25 leaves m‐2, A. viridis settled in approximately equal numbers. Patterns of settlement for all other species combined were similar to those for A. viridis. During the experiment, an epiphytic alga. Giffordia mitchellae, colonized and grew on the ASU. The alga increased the structure associated with the experimental units. Treatment leaf densities could thus be regarded only as relative measures of shelter. At low leaf densities, fish settlement increased with increasing algal cover; at higher leaf densities, the opposite occurred. The rapid increase in abundance of recently settled fish over a relatively narrow range of leaf densities above zero implies that small increases in shelter can have large effects on settlement of larval fish.
Energy dynamics of grasshopper populations in a temperate grassland community in India
Authors: KAUSHAL B. R. , JOSHI P. C. 
Published: July 2006

AbstractPopulation dynamics, biomass and secondary net production of orthopterans, particularly acridids, were studied in a temperate grassland at Naukuchiatal, India, from February 1986 to January 1988. A total of 38 plant species were recorded in the grassland and mean aboveground net primary production was 6760 kJ m‐2 per year. Thirteen orthopteran species occurred in the grassland. Most individuals were acridids, followed by tettigonids and gryllids; acridids were dominant both in density and biomass. The maximum population density was 5 m‐2 and the maximum biomass was 275 mg m‐2. Mean secondary net production was 10 kJ m‐2 per year. Acridids consumed an average of 2.3% of the above‐ground primary production.
Effects of fuel reduction burning on epigeal arthropods and earthworms in dry sclerophyll eucalypt forest of west‐central Victoria
Authors: NEUMANN F. G. , TOLHURST K. 
Published: July 2006

AbstractThe effects of prescribed low‐intensity burning during spring and autumn on invertebrates in litter/upper soil were assessed in dry sclerophyll mixed eucalypt forest near Daylesford, west–central Victoria. The 4‐year study was based on 68 848 arthropod specimens representing 29 ordinal or lower level taxa contained in 1980 pitfall trap samples, and on in situ counts of earthworms (Annelida) in 2220 litter/upper soils samples.The spring bum caused short‐term reductions in activity among the common ‘major’ taxa Collembola (springtails) and Diptera (flies), and among the rarely trapped ‘minor’ taxa Opilionida (harvestmen), Lepidoptera (moths) and Apocrita (parasitic wasps) for up to one year. These reductions were associated with low fine fuel loads in the first year after the fire. Populations of earthworms also declined substantially, but recovered within 3 years of the burn. The autumn burn suppressed the Collembola and the ‘minor’ taxa Blattodea, Polydesmida, Thysanura and Tettigoniidae for up to 10 months. Earthworms were not affected. Very dry soil conditions were associated with depressed collembolan activity at study sites irrespective of burning.Given the importance of Collembola, larval Diptera and earthworms among decomposers in forest litter, it appears that the spring burn, and to a lesser extent the autumn burn, may have temporarily reduced the decomposer cycle. Further research on individual species is required to substantiate this conclusion, and also on the effects of high frequency burning. In the interim, any broadscale fuel reduction burning in forest ecosystems similar to that studied here should be scheduled for autumn rather than spring to protect earthworms and no burning should be permitted during drought periods, to minimize adverse impacts on the overall invertebrate fauna inhabiting litter/upper soil.
Seasonal changes in activity of subterranean termite species (Isoptera) in Western Australian wheatbelt habitats
Authors: ABENSPERG‐TRAUN MAX 
Published: July 2006

AbstractSubterranean termite assemblages in woodland, mallee and heath habitats of the Western Australian wheatbelt were sampled for seasonal changes in species richness and species abundance. The study was carried out in Durokoppin and Kodj Kodjin Nature Reserves between January and November 1988, and a trench method was used to sample termites. Species richness changed over time, with monthy means of: woodland 10 species (range: 5–15), mallee 8 species (range: 4–15), heath 8 species (range: 5–15). Species richness was highest in autumn and spring when termite activity in the soil was also highest due to favourable soil moisture.Amitermes neogermanusandTumulitermes petiluswere the most abundant species in woodland and mallee in all seasons. During summer, the pooled observations of these two species accounted for 50% (woodland) and 82% (mallee) of all observations. Their predominance may be due to greater tolerance of low soil moisture and a more diverse diet than obligate wood‐feeders (e.g. Rhinotermitidae). The latter were generally absent near the soil surface in summer, possibly because food sources deeper within the soil were utilized. Four species were abundant in heath:Tumulitermes dalbiensis(monthly mean 20% of all species observations),T. comatus(13%),Amitermes. sp.‘R’ (18%)andDrepanotermes rubriceps(12%). These four species showed no seasonal change in their relative abundance, possibly because their diet restricted them to surface‐foraging.
Changes in subtidal habitat following mass mortality of sea urchins in Botany Bay, New South Wales
Authors: ANDREW N. L. 
Published: July 2006

AbstractOn two occasions, between June and October 1986 and April/May 1988, mass mortality of the sea urchin Centrostephanus rodgersii occurred at Bare Island in Botany Bay, New South Wales. Following the widespread disappearance of C. rodgersii in August 1986, the abundance of filamentous and foliose algae increased and crustose corallines declined. There was also a large, but shortlived, increase in the density of limpets, particularly Patelloida alticostata, which then fell to nearly zero after 15 months. In October 1986, the habitat found at other sites in Botany Bay was consistent with a recent disappearance of C. rodgersii. At all sites a complex assemblage of non‐crustose algae developed, the species composition of which differed among sites. A large recruitment of C. rodgersii was observed at all affected sites in February 1987 and January 1988. These individuals grew quickly and reached a mean size of approximately 35 mm test diameter at the end of their first year.
Fungal pathogens as selective forces in plant populations and communities*
Authors: BURDON J. J. 
Published: July 2006

AbstractPathogens are potent selective forces whose importance in shaping the size and structure of individual plant populations and whole communities has been underestimated. Even in situations where host and pathogen have been associated over long periods of time, pathogens regularly affect host fitness by reducing fecundity and increasing mortality either directly or indirectly through reductions in competitive ability.The genetic consequences of such disease‐induced reductions in fitness are profound. On a broad geographic scale, race‐specific resistance generally occurs more frequently in regions characterized by environments favourable for disease development. Within such areas, however, the distribution of resistant plant genotypes is often very patchy. This probably reflects the importance of extinction and colonization events in the continuing co‐evolutionary dynamics of host‐pathogen associations.At a demographic level, pathogen‐induced reductions in host fitness may lead to changes in the size of populations. In turn, this may lead to changes in the relative diversity of whole communities. Documentation of this scale of interaction is poor, but the devastating consequences of the introduction of pathogens into alien environments provides a salutary reminder of their power to change plant communities radically.
The effects of ants on herbivory and herbivore numbers on foliage of the mallee eucalypt,Eucalyptus incrassataLabill.*
Authors: MACKAY DUNCAN A. 
Published: July 2006

AbstractAlthough there has been much recent interest in ant‐plant mutualisms, few data are available on the effects of foraging ants on herbivore numbers and levels of herbivory on plants that do not offer specific inducements to attract ant visitation. In forestry plantations and tropical crops, ants have erratic but sometimes dramatic effects on the numbers of insect herbivores but, in more natural habitats, their effects on levels of herbivory appear to be largely unknown. In Australia, where ants andEucalyptuswoodlands are ubiquitous and abundant and where considerable debate has occurred regarding levels of herbivory inEucalyptusforests, very little work has been done to examine the effects of ants on densities of insect herbivores on eucalypts.In this study, ants were experimentally excluded from mature and immature foliage of saplings of the malleeEucalyptus incrassatain South Australia, and herbivore numbers and levels of leaf herbivory were assessed during the next 6 months. No significant differences in herbivory were found between ant‐access and ant‐exclusion treatments. In spring and early summer, ants were found in associations with aggregations of eurymelid bugs on young foliage, and the effects of ants on bug densities were experimentally investigated. Bug densities decreased rapidly in ant‐exclusion treatments compared with ant‐access controls. Ants also quickly removed seeds ofE. incrassatafrom experimental caches.The potential of ants to limit the numbers of insect herbivores on eucalypts seems limited given their tendency to form mutualistic associations with sap‐feeding Homopterans and because of a lack of other herbivores that are particularly vulnerable to ant predation.
Colonization of pasture by Kunzea ericoides in the Tidbinbilla Valley, ACT, Australia
Authors: KIRSCHBAUM SARAH B. , WILLIAMS DAVID G. 
Published: July 2006

AbstractStand morphometry and age structure were analysed for populations of burgan, Kunzea ericoides, which were colonizing pastoral land in the Tidbinbilla Valley, Australian Capital Territory. Three types of stands, (i) closed burgan‐dominated; (ii) open burgan‐dominated; and (iii) mixed burgan and eucalypts, were compared at each of two locations. Burgan ages were determined from growth ring counts cross‐correlated with seasonal rainfall and annual increments in Pinus radiata. Burgan stands have developed from windblown seed coming from nearby forest margins and drainage‐lines. The species colonized rural lands in the Tidbinbilla Valley rapidly from the early 1960s, when changes in land use practices occurred which enabled sparse colonists to contribute to rapid population expansion. Colonization was initially slow, but recruitment increased dramatically in the early 1960s in closed and open stands when densities were between 0.01 and 0.03 plants m‐2. These stands did not follow classic secondary succession, as the differences between stands sampled were largely the result of differences in burgan density and floristic composition of the sites at the time of change in land use practices. These differences in turn influenced the phenotypic response of individual plants and the ensuing stand structures. A closed shrub canopy of burgan, together with the species self‐replacement strategies, is likely to prevent other species from entering the closed burgan sites and becoming dominant. Where the objective is to limit the spread of burgan, isolated plants, which act as foci for spread, would be the primary target for control.
Predicting the abundance of hollow‐bearing trees in montane forests of southeastern Australia
Authors: LINDENMAYER D. B. , CUNNINGHAM R. B. , NIX H. A. , TANTON M. T. , SMITH A. P. 
Published: July 2006

AbstractPoisson regression analyses were used to relate the number of hollow‐bearing trees on 523 sites in the montane ash forests of the Central Highlands of Victoria to a range of environmental variables. Region, logging history, the dominant species of eucalypt, slope angle, topographic position and the age of the stand influenced significantly the number of hollow‐bearing trees. A simple predictive model containing these factors has possible application in geographic information systems and may assist in the assessment of wildlife habitat.The number of multi‐aged stands and living trees with fire scars indicates that some individuals of ‘fire‐sensitive’ montane ash eucalypts appear to survive intense wildfire.
Nectar depletion and its implications for honeyeaters in heathland near Sydney
Authors: ARMSTRONG DOUG P. 
Published: July 2006

AbstractSeveral researchers have attempted to calculate whether depression of nectar resources by Australian honeyeaters is likely to limit their densities. Such calculations can be misleading, however, and do not directly test whether birds depress nectar availability. I monitored changes in nectar availability during the 8–9 months that honeyeaters bred in heathland near Sydney, and caged inflorescences to test whether nectar availability was being depressed by birds.There were pronounced seasonal changes in nectar availability in each of 2 years, and caging substantially increased the amounts of nectar in inflorescences during months when nectar production was low. The effects of caging must have resulted from exclusion of honeyeaters, as: (i) open‐ended cage controls showed that the effects of caging resulted from exclusion of foragers, not from artifacts of caging; (ii) day‐only and night‐only caging showed that nectar was depleted only during the day: and (iii) observations showed that cages did not exclude any diurnal foragers other than honeyeaters. Resident honeyeaters spent more time foraging during months when nectar was scarce, implying that the rates at which they could obtain nectar were affected by changes in nectar availability. It is therefore possible that the depletion of nectar by honeyeaters could have limited their densities. However. I argue that such limitation could only be inferred safely if nectar‐supplementation experiments showed survival and/or reproduction to be limited by nectar availability.
Response of a monsoon forest‐savanna boundary to fire protection, Weipa, northern Australia
Authors: BOWMAN D. M. J. S. , FENSHAM R. J. 
Published: July 2006

AbstractA numerical floristic analysis of samples across a monsoon forest‐savanna boundary, from an area that had been actively protected from fire for 15 years, at Weipa, northern Australia, revealed three communities: (i) a monsoon forest with a low closed canopy composed mainly of tree species with extra‐Australian tropical affinities and a sparse ground layer; (ii) an ecotone with a distinct closed microphyll shrub layer beneath the open canopy of savanna trees; and (iii) a savanna dominated by Eucalyptus tetrodonta. The development of the ecotone has occurred since fire protection and is of limited extent within the fire protected block. The monsoon forest occurred on soils with significantly higher concentrations of bauxitic pisoliths than the other two communities. Soils under the monsoon forest had significantly higher concentrations of total K, S, C, N, exchangeable K and Ca, and higher pH and electrical conductivity than for soils of either of the other communities. A positive relationship between woody basal area and concentrations of surface soil total P, N, C, exchangeable Ca, CEC and gravel was detected across a 20 m transect from the ecotone community into the savanna. The invasion of monsoon forest seedlings was greatest in the ecotone, with few occurring in the savanna. It appears that the expansion of the monsoon forest requires the development of a layer of shrubs. The mechanism of this facilitation is unclear, although the possible role of nutrient enrichment by the shrubs requires further investigation.