bluuebunny/crossref_metadata_2025_split huggingface dataset:
Biological activity, field persistence and safe recropping intervals for imazethapyr and rimsulfuron on a silty‐clay soil
Authors: ONOFRI A. 
Published: July 2006

SummaryGreenhouse and field trials were carried out from 1990 to 1993 on a silty‐clay soil in central Italy to assess the risk of carry‐over of imazethapyr and rimsulfuron residues. Turnip and sunflower were the most sensitive species to rimsulfuron residues (damaging thresholds lower than l ng a.i. g‐1), whereas sugar beel. turnip, oilseed rape and grain sorghum proved to be the most sensitive species to imazethapyr (damaging thresholds ranging from 0.5 to 6 n g a.i. g‐1). The time required for 50% imazethapyr disappearance (DT50) from the upper soil layer (0‐0.1 m)ranged from 18 to 21 days, whereas the DT50for rimsulfuron ranged from 5 to 6 days. Safe recropping intervals on soil treated with imazethapyr (rate of 35 g a.i. ha‐1) ranged from 3–4 weeks for the least sensitive species (maize, sunflower and mustard) up to 5–6 months for the most sensitive ones (sugar beet and turnip). For rimsulfuron (rate of 15 g a.i. ha‐1), recropping intervals of 2–3 weeks proved to be long enough to avoid injuries to any crops, except for the most sensitive species (turnip), which required 6 weeks before it could be safely sown in treated fields. Simple greenhouse bioassays allowed reliable predictions to be obtained about injuries observed in the field, confirming their usefulness to forecast the risk of carry‐over of residues.
Penetration of triolein and methyl oleate through isolated plant cuticles and their effect on penetration of [14C]quizalofop‐ethyl and [14C]fenoxaprop‐ethyl
Authors: SANTIER S. , CHAMEL A. 
Published: July 2006

SummaryThe penetration of two model seed oil compounds, [14C]triolein (TRI) and [14C]methyl oleate (MEO) through plant cuticles and their effects on the penetration of [14C]quizalofop‐ethyl and [14C]fenoxaprop‐ethyl were investigated. Experiments were carried out using isolated cuticles from rubber plant (Ficus elastica Roxb.) leaves and from tomato (Lycopersicon esculentum Mill,) and pepper (Capsicum annuum L.) fruits. Chemicals were deposited in droplets on to cuticle discs maintained on agar blocks under controlled conditions. TRI and MEO were used at 1% (V/V). The transfer of radiolabel through cuticles was negligible for TRI and varied from 6 to 13% after 72 h, according to species, for MEO, The penetration results obtained for quizalofop‐ethyl (0.084 mg mL‐1) and fenoxaprop‐ethyl (0.189 mg mL‐1) were very similar and varied according to species. The greatest diffusion intoagar was observed for pepper (12.8% and 10.7% after 72 h, for quizalofop‐ethyl and fenoxaprop‐ethyl respectively), the lowest for rubber plant cuticles (1.4 and 1.3% respectively). Addition of MEO produced significant increases in the penetration of quizalofop‐ethyl and fenoxaprop‐ethyl through rubber plant and tomato cuticles. TRI had an enhancing effect on the two herbicides only with rubber plant cuticles. Results are discussed with particular consideration of the variations between plant species and the possible mode of action of seed oil adjuvants.
A review of the role of fire in nutrient cycling in Australian native forests, and of methodology for studying the fire‐nutrient interaction*
Authors: RAISON R. J. 
Published: July 2006

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 briefly.
Hydrology and fish diversity of a North Queensland tropical stream
Authors: BEUMER J. p. 
Published: July 2006

AbstractThe diversity and distribution of fish and the hydrology of the Black‐Alice River System, North Queensland, are described from a 2‐year study (September 1972 to August 1974). Most physico‐chemical parameters measured exhibited seasonal patterns which are influenced by rainfall and discharge. A total of forty‐one species of fishes belonging to four groups: freshwater tolerant, saltwater tolerant, diadromous and sporadic, were recorded during the study. The diversity of fish species decreased with increasing distance from the mouth of the system. Fluctuations in total diversity (H') were due to variations in ‘species richness’ (D) rather than to equitability (E). The ability of the fish community to ‘recover’ its diversity and longitudinal distribution after a flood of above‐average magnitude is demonstrated.
Natural physical disturbance and predation: their importance in structuring a marine sessile community
Authors: MORAN P. J. 
Published: July 2006

AbstractSettling panels were used to determine the distribution of sessile organisms. Experimental and control cages were located at two study sites that were of different physical exposures. Twenty‐nine species of sessile organisms were recorded for the two sites. Data on the presence or absence of each species, for each sample, were classified.The resulting hierarchy showed natural physical disturbance to be the major structuring factor in the community.Predation was of less importance in the physically stressed study site and had no effect on species distribution in the protected site.
Field studies of nitrogen fixation of Australian alpine plants and soils
Authors: CARR D. J. , CARR S. G. M. , PAPST W. R. 
Published: July 2006

AbstractAlpine grassland areas in Victoria and New South Wales have been subjected to summer grazing by cattle and sheep for well over a hundred years. Legumes other than a few species of shrubs, which provide a very small percentage of the vegetation cover in the grasslands, are absent. Other alpine communities include Sphagnum ‘mossbeds’ in the valleys and areas of snowgum woodland and shrubland. Virtually nothing is known of the mineral status of these communities and nothing of their nitrogen economy. On the Bogong High Plains, enclosure of grassland and of Sphagnum mossbeds from grazing and trampling has resulted, in the last few decades, in considerable changes in both cover and composition of the vegetation.A portable gas chromatogram was used to carry out determinations of the capacity of samples of the grassland and Sphagnum to support acetylene reduction to ethylene, by convention equated to a capacity to fix nitrogen. There appears to be a substantial capacity for acetylene reduction associated with the rhizosphere of the grasses (Poa australis agg.).The capacity of the Sphagnum for acetylene reduction is even greater and appears to be due to facultative anaerobes, abundant only in the upper, living part of the Sphagnum. These organisms may depend in part on leakage of photosynthate from the living Sphagnum. Associations of Sphagnum with blue‐green algae appear to be unusual in contrast with work on Swedish subarctic mosses, which is discussed.The only non‐leguminous Australian alpine plant so far examined for nitrogen fixation is Podocarpus lawrencei. A capacity for acetylene reduction was found for neither the nodules of the roots of this plant nor the associated soils.
The diet of the New Holland honeyeater, Phylidonyris novaehollandiae
Authors: PATON DAVID C. 
Published: July 2006

AbstractNew Holland honeyeaters collect nectar, manna or honeydew for energy and hawk small flying insects for protein. The insects taken were usually Diptera and Hymenoptera weighing 0.7 mg dry weight or less. Net rates of energy gain from hawking small flying insects were usually less than 20 J min−1 and sometimes negative and insufficient to meet the bird's daily energy requirements. Those from feeding on nectar, manna or honeydew were usually above 40J min−1 and often above 400J min−1 at dawn and the birds depended on these carbohydrates for energy. Nectar, manna and honeydew contained negligible amounts of protein, and the birds used small flying insects as sources of protein, and presumably other nutrients. Given that carbohydrate resources supply better rates of energy gain than insects. New Holland honeyeaters should collect their energy requirements from carbohydrates and only collect sufficient insects to satisfy their protein requirements. Estimates of the food intakes of both non‐breeding and breedig birds showed that they did this. Non‐breeding New Holland honeyeaters collected from 72 to 125 (mean 92) kJ of carbohydrates per day and 17 to 58 (mean 31) mg of protein per day. These meet the daily energy (75 kJ) and protein (20 mg) requirements of the birds. Breedig birds collected more carbohydrates and more insects, but in proportion to their increased energy and protein requirements respectively.New Holland honeyeaters are probably limited by their ability to meet their energy requirements from nectar, manna or honeydew and not by insects. Non‐breeding birds collected their protein requirements in about 10 min of insect‐feeding, but spent from 33 to 90% of the day collecting carbohydrates to meet their energy requirements. The maintenance requirement of 20 mg of protein per day for New Holland honeyeaters is about 25% of that estimated from standard equations for a bird of the same size. This low level may have evolved in response to low energy availability.
Seed predation in native legumes of south‐eastern Australia
Authors: AULD TONY D. 
Published: July 2006

AbstractSeed predation in 28 species of native legumes in the Sydney region was examined. While bruchids are significant seed predators in the Sydney region they are not the dominant seed predators group, as is the case in central America. Other important groups include weevils, anthribids and lepidopterans. In each group of seed predators studied, apart from the lepidoptera, a particular genus was closely associated with a single plant genus. The degree of seed predation varied from 85% to 3%, with only six of the 28 species of plants studied relatively free from seed predation (less than 10% seed‐crop losses). Variation in the degree of seed predation both within and between plant genera could not be explained by taxonomic relationships, morphology, distribution, seed weight or seed dispersal agents. A larger data base is necessary to account for such variations.
Phytophagous insect communities in the canopies of three Eucalyptus forest types in south‐eastern Australia
Authors: OHMART C. P. , STEWART L. G. , THOMAS J. R. 
Published: July 2006

Abstract Intensive sampling of tree canopies for phytophagous insects was carried out in three contrasting eucalypt forest types comprised of species widely distributed in sub‐alpine forests in Victoria and New South Wales (Eucalyptus delegatensis, E. dives, and E. pauciflora). The number of phytophagous insects present in the canopies of these forest types was low, with a seasonal average of 20 individuals per kg of foliage (dry weight). Numbers were much lower than expected from past literature reporting‘chronically high’levels of defoliation in eucalypt forests. Microlepidoptera, Geometridae, Chrysomelidae, and Curculionidae were the major leaf‐chewing groups recorded. Most sap‐feeders were either leafhoppers (Cercopidae and Cicadellidae) or in the superfamily Fulgoroidea. Psyllidae and gall‐making species were rare. Leafhoppers made up a very large portion of the phytophagous insect communities in each forest type, particularly in the E. dives forest. Microlepidoptera was the most commonly encountered defoliator group in all three forest types making up 33‐44% of the total count. Non‐phytophagous arthropods accounted for 44‐48% of all individuals encountered. The density of insect defoliators was greater in the lower crown than upper crown. The E. dives canopy supported many more phytophagous insects per unit weight of foliage, as well as more per hectare, than the other two forest types. The greatest number of phytophagous species was also encountered in E. dives canopy. The E. delegatensis canopy supported the lowest number of phytophagous insects per unit weight of foliage as Well as numbers per hectare. Abundance of insect defoliators in the eucalypt forest types in this study was similar to published figures of insect defoliators in northern temperate forests.
The occurrence of mixed stands of the Eucalyptus subgenera Monocalyptus and Symphyomyrtus in south‐eastern Tasmania
Authors: DUFF G. A. , REID J. B. , JACKSON W. D. 
Published: July 2006

Abstract Mixed stands of eucalypts were examined on several sites in south‐eastern Tasmania. Species from the subgenus Monocalyptus (E. puchella and E. obliqua) became dominant over species from the subgenus Symphyomyrtus (E. viminalis and E. globulus) as the age of the stand increased. In glasshouse trials, Symphyomyrtus species were initially at an advantage since they were more opportunistic than Monocalyptus species owing to their more rapid and even germination and higher initial growth rates. In addition, the Monocalyptus species E. pulchella showed a greater tendency to regenerate vegetatively than the Symphyomyrtus species E. viminalis and E. ovata.
The role of soil mobility in controlling a vegetation gradient
Authors: BUCKLEY RALF C. 
Published: July 2006

AbstractMature plants of species which characteristically occupy the mobile crests and upper slopes of the central Australian sandridges are more tolerant of sand burial or undercutting than those of the lower slopes and swales. Seedlings growing on the mobile crest areas are susceptible to sand burial, even during wet years. The young shoots of vegetatively spreading species are less susceptible than individual seedlings of the same size.
Seasonal and diurnal variations in the energetics and foraging activities of the brown honey eater, Lichmera indistincta
Authors: COLLINS BRIAN G. , BRIFFA PETER 
Published: July 2006

AbstractIn general, the brown honeyeater, Lichmera indistincta, flies more and expends more energy when visiting flowers in the early morning than at other times. Floral nectar is most abundant early in the day, and nectar energy intake by L. indistincta is greatest at that time. It appears as if birds can only store excess energy during the early part of the day, incurring energy deficits at other times. Unit perching and flight costs are greatest for L. indistincta in winter and spring. As a result, peak total energy expenditures and requirements occur at these times, birds apparently being unable to reduce energy demands by employing nocturnal torpor. Estimates of probable energy uptake by L. indistincta from the plant species studied exceed predicted requirements in all seasons except winter, when it is apparent that birds would need to be especially selective in the plants that they used as major energy sources.
Populations of the bush fly (Musca vetustissima Walker) in arid Australia
Authors: MATTHIESSEN J.N. 
Published: July 2006

AbstractPopulations of the bush fly Musca vetustissima were usually low in arid south‐western Australia. Herbaceous plants that grew only after rain resulted in changes to cattle dung that increased its attractiveness to bush flies for oviposition in laboratory tests. Larvae reared in such dung consistently produced large flies of high fecundity, and larval survival was usually high. Similar responses to the dung were evident from examination of flies sampled in the field. Although greatly increased bush fly abundance was possible only after major improvement in cattle dung, it was not a general phenomenon as immature survival did not always increase. Even major population increases resulted from periods of high immature survival that were brief relative to the duration of favourable dung. Nematodes Heterotylenchus sp. appeared to be an important mortality factor of the immature stages at such times.Build‐up of high bush fly populations occurred only in cattle‐grazing areas, but base‐level abundance was similar regardless of the presence of cattle. Almost all female flies were gravid when cattle dung was unfavourable for breeding, and in areas without cattle. In arid areas, acceptable oviposition sites probably are more limiting than are sources of protein for oögensis.
A radar and aerial‐trapping study of an early spring migration of moths (Lepidoptera) in inland New South Wales
Authors: DRAKE V. A. , FARROW R. A. 
Published: July 2006

AbstractThe migrations of a number of species ofnoctuid and pvralid moths were studied with a specialpurpose radar unit and by direct sampling with a kite‐borne net at a locality in central‐western New South Wales during the early spring of 1980. The observations coincided with the appearance of very large numbers of moths throughout much of south‐eastern Australia, and immediately followed a major caterpillar plague in south‐western New South Wales. The migrations occurred mainly at night, and were most intense during periods of warm weather. Several different directions of migration were observed, but the movements were always approximately downwind; distances of a few hundred kilometres were typically covered during a single night. A number of quantitative measures of the migration intensity have been estimated for some of the flights. The migrating population frequently exhibited a degree of mutual alignment, which was sometimes in a direction different from that of the migration. Migrants became concentrated into layers at high altitudes (up to 1900 m) on two occasions during the night. Similar high‐altitude migrations were also detected during daylight. It is inferred that an early spring re‐invasion of drought‐affected inland areas, and of areas on the continental periphery which have a cool winter climate, by means of long‐distance migrations from inland areas where autumn and winter conditions have been favourable for larval development, is an almost regular feature of the population dynamics of several moth species that are of economic importance in south‐eas‐tern Australia. These migrations are interpreted as an adaptation to the geographie and climatic factors that control larval development and moth flight in this region, and especially to the erratic rainfall regime of the inland source areas.
Winter energy deficits and the importance of fruit versus insects in a tropical island bird population
Authors: CATTERALL CARLA P. 
Published: July 2006

AbstractThe sedentary population of 200 to 500 silver‐eyes on Heron Island, Australian Great Barrier Reef, experiences high mortality during the winter non‐breeding season. The omnivorous silvereyes feed mainly on small insects gleaned from foliage, and on fruits, especially the fig Ficus opposita. Estimates of the energy content of food items reveal that small insects (2–5 mm long) provide little assimilable energy (9 J), whereas large insects (>8 mm) and bites of fig provide most assimilable energy (217 J and 181 J respectively).An analysis of the average daily intakes and expenditures (estimated by the time‐budget method) for three sampling occasions showed that the rates of insect consumption (10,15 and 11 kJ day‐1) were significantly less than the energy requirements (37, 38 and 37 kJ day‐1). While many individuals may have been able to balance their energy budgets by eating figs, the calculated fruit intake rates (38, 9 and 0.5 kJ day‐1 respectively), together with high inter‐individual variation in fig consumption, suggest that figs were often in short supply. The birds visited fig trees most frequently during the first 2 h after sunrise, and the feeding success rate in fig trees (approximately 20% of visits successful) during this time was significantly greater than that during the rest of the day (approximately 10% of visits successful). Alternative hypotheses for these patterns, based on protein requirements, on diurnal rhythms imposed by insect availability, or on satiation, are considered and rejected.These results indicate that the pre‐breeding population size is limited by winter energy shortage, the extent of which is dependent on the size and phenology of the fig crop. Natural selection should favour individual strategies for maximization of net energy intake.
Rates of litterfall and organic matter turnover at three South Australian indigenous forest sites
Authors: HUTSON BARRY R. 
Published: July 2006

AbstractA quantitative study of the litterfall rate, litter mass and the organic carbon content of litter and soil at three South Australian low open‐forests was made monthly for 2 years. The soil and dominant vegetation at the sites were similar, but the mean annual rainfall differed; 635, 690 and 1050 mm respectively at the ‘dry’, ‘medium’ and ‘wet’ sites.Mean annual litterfall at the dry, medium and wet sites was 114, 205 and 233 g m−2 respectively, and the mean mass of the litter layer was 885, 1153 and 858 g m−2 Leafy material formed 82% of the litterfall at each site and maximum fall occurred in the summer. Leafy material formed 64–68% of the three litter layers and there was no general pattern of seasonal change of mass.The data obtained were used to calculate the half‐life (T1/2 of the litter, the values were 5.4, 3.9 and 2.6 years respectively at the dry, medium and wet sites. The values from the medium and wet sites fit within the range previously recorded for other open‐forests and low open‐forests, but indicate an extremely slow rate of decomposition at the dry site, which was located close to open‐scrubland.The amounts of organic carbon in the 0–8 cm layer of soil at the dry, medium and wet sites were 777, 928and 950 g m‐2 respectively. However, without a detailed investigation of the source of soil carbon, these values could only be used to show that the organic carbon store to a depth of 8 cm is equivalent to 9–15 times the annual litterfall input.
Seasonal prevalence of adult mosquitoes at Casuarina and Leanyer, Darwin
Authors: RUSSELL RICHARD C. , WHELAN PETER I. 
Published: July 2006

AbstractMosquito populations were sampled fortnightly for 2 years, using EVS solid CO2 baited light traps, to monitor seasonal activity of females in the vicinity of new urban development at Casuarina Swamp and Leanyer Swamp, Darwin. The relative abundance of different species was related to seasonal conditions and the influence of urban stormwater on the larval habitats within the two environments.Differences were observed between sites due to the site ecology, and between years and between seasons but, in general, the early dry season was dominated by Culex annulirostris, Anopheles bancroftii and An hilli, while Aedes vigilax and Cx annulirostris were predominant in the late dry season and early wet season at both sites. The late wet season at Leanyer Swamp was dominated by An hilli and An bancroftii, while at Casuarina Swamp, Cx annulirostris was the predominant species. The prevalence of vector species indicates the need for control measures to protect the local communities from mosquitoborne disease.