bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of non‐ionic nonylphenol surfactants on surface physicochemical properties, uptake and distribution of asulam and diflufenican
Authors: SHARMA S. D. , KIRKWOOD R. C. , WHATELEY T. L. 
Published: July 2006

SummaryThe effect of non‐ionic nonylphenol (NP) surfactants containing 4–14 ethylene oxide (EO) molecules on the distribution of asulam and diflufenican was investigated in Pteridium aquilinum L. Kuhn and Avena fatua L. The distribution of the herbicides was dependent on the EO content and concentration of surfactant and differed between plant species and herbicide. The surface properties of contact angle, droplet diameter and surface tension were examined. For solutions of asulam, the greatest reductions in contact angle, surface tension and greatest droplet diameter were obtained with surfactants of EO 6.5–10 (at 0.001–0.1%). For solutions of diflufenican, these responses were greatest when applied with surfactant of EO 4. Surfactants of EO 6.5–10 increased the uptake and translocation of [14C]asulam in P. aquilinum, particularly at surfactant concentrations of 0.01 % and 0.1 %. All surfactants increased uptake of [14C]asulam in A. fatua with no significant effects of surfactant EO number or concentration. For both species, there was a positive correlation between the optimum surface characteristics of the herbicide droplets and the uptake of asulam. With diflufenican, greatest uptake and translocation by mature frond tissue of P. aquilinum occurred at the highest concentration of surfactant EO 4; in A. fatua, however, uptake and translocation were not significantly affected by any of the surfactants.
Influence of nitrogen on competition between cereals and their natural weed populations
Authors: JØRNSGÅRD B. , RASMUSSEN K. , HILL J. , CHRISTIANSEN J. L. 
Published: July 2006

SummaryThe effects of nitrogen fertilizer on the growth and density of natural weed populations in spring barley (Hordeum vulgare L.) and winter wheat (Triticum aestivum L.) were investigated in the absence of herbicide. An increased level of applied nitrogen did not enhance: weed germination, tended to decrease the total weed biomass and had a differential effect upon the biomass of individual weed species in both wheat and barky. In competition with barley, Chenopodium album L. and Lamium spp. had lower nitrogen optima than the crop, while Urtica urens L. had a higher nitrogen optimum. In competition with wheat, Stellaria media (L.) Vill., Lamium spp. and Veronica spp. had lower nitrogen optima than the crop. The systematic changes in nitrogen effect with time were analysed by fitting orthogonal polynomials to the growth and density curves. The methodology could be recommended for other studies in which time or other systematic factors are included, as it supplies information which a traditional analysis of variance cannot provide. Since seed production is positively correlated with biomass, so nitrogen level affects seed production and, hence, the seed pool and future weed population, suggesting that fertilizer usage can be exploited in an integrated programme of crop: weed management. A trend towards lower N fertilizer application owing to concerns about the environment willfavour most of the weed species investigated in these experiments and change the composition of weed populations.
Weed populations in olive groves under non‐tillage and conditions of rapid degradation of simazine
Authors: SAAVEDRA M. , PASTOR M. 
Published: July 2006

SummaryIn 49 olive tree groves in southern Spain under non‐tillage and treated in the autumn with simazine, a total of 315 weed species was identified. However, only eight annual specics reached a moderate mean infestation of infested ficlds. In each field the number of observed species ranged from 4 to 78. The most important annual species that survived simazine treatment were Lolium rigidum, Galium tricornutum and Sherardia arvensis and, locally in a few fields, others such as Amaranthus spp., Conyza spp., Pulicaria paludosa, Sinapis alba. Torilis arvensis and Rumex bucephalophorus. Sedum album, R. bucephalophorus, P. paludosa, Briza maxima and Hypericum perforatum were mainly found in slope soils with high altitude and low carbon content. Cyperus rotundus, Conyza banariensi, Amaranthus blitoides, Galium spurium and Diplotaxis virgata were found at high densities in irrigated fields. Simazine residues recorded 6 months after herbicide application were very low, amounting on average to levels less than 3% of the applied rate. In soil treated with simazine for 7 years. simazine degradation was much faster than in previously untreated soil, particularly at temperatures of 15‐25°C.
Estimation of the seedbank of Striga spp. (Scrophulariaceae) in Malian fields and the implications for a model of biocontrol of Striga hermonthica
Authors: SMITH M. C. , WEBB M. 
Published: July 2006

Summary Striga seeds were extracted from soils collecled in Mali and the viahility of these seeds was estimated. Striga seeds were found in 45 of 46 samples taken from 23 fields. Siriga hermonthica (Del.) Benth. growmg on the host crop millet, was present at all 46 sites sampled. The a size uf the Striga seedbaiik measured lo a depth of 15 cm was estimated to be 38 800 m ‐2 of surface area (geometnc mean 11 500). The average number of S. hermonthica plants observed per millei hill was 8.83 (geometric mean 3.89) or 13.98 m‐2 (gcometrie mean 5.69 m‐2). Higher crop hill densities tended to result in higher densities of emerged S. hermonthica per hill. The relationship between seeds m‐2 and S. her‐monhica plants m‐2 was fitied to a reetungular hyperbola and used to reassess an existing model of S. herniouhica control.
Flux in the sublittoral macrobenthos of Moreton Bay
Authors: STEPHENSON W. 
Published: July 2006

AbstractSeveral different intertime dissimilarity measures, used with a variety of standardisations of data, were applied to transformed data of macrobenthic species at six sites. These data were obtained over twenty‐two times at 8‐week intervals. Results were evaluated by stepwise regressions (linear, annual cyclical, longer term cycles). Manhattan metric flux between consecutive times was preferred for most subsequent purposes. This flux divided into positive and negative components which measure, summated over all species, rates of recruitment and depletion. Use of algebraic and absolute sums permits evaluation of an index of homeostasis which measures the counterbalancing of recruitment by some species and depletion by others; this index had a value of ca 0.7.Use of the Manhattan metric with catch standardized data indicated changes of community composition at the (more coastal) Bramble Bay sites with a roughly 3‐yr cycle and at the (more oceanic) Middle Banks sites with a roughly 51/2‐yr cycle.In the main analyses, sites were considered individually and in various groupings. It was shown that at Bramble Bay the optimum near‐annual periodicity gives a 50‐instead of a 52‐week year, and also that with increased numbers of sites in a grouping, the greater the significance of the near‐annual cycles.An hypothesis is outlined involving ‘counterbalancing’ between sites of depletion rates due to mobile predators or ‘disturbers’ (fish and prawns). The counterbalancing of recruitment rates is linked to depletion, and is in line with Caswell's (1978) somewhat theoretical paper in which he suggested the temporary action of predation opens up new cells for colonization.This hypothesis goes far towards ‘explaining’ the known patchiness of benthos in Moreton Bay. Also if mobile predators are a link between areas in proximity with different biotas the ecological unit (2 ‘community’) is necessarily expanded.
The light‐brown apple moth, Epiphyas postvittana (Walker): 5. Variability of demographic characteristics in field populations of southeastern Australia.
Authors: GEIER P. W. , BRIESE D. T. 
Published: July 2006

AbstractStudies of population samples of the light‐brown apple moth (LBAM), Epiphyas postvittana (Walker), collected along a 1500 km north‐south transect in southeastern Australia, revealed significant differences in demographic performance between cohorts of different origins reared under uniform conditions in the laboratory. Mean sample values for survivorship and rate of pre‐imaginal development, notably, were found to vary according to the latitude and mean January temperature of collection sites, suggesting that specialized forms had evolved in LBAM as an adaptive response to the characteristics of local environments. Underlying this general trend, however, great differences were recorded between samples from neighbouring populations, in actual values manifested for specific properties affecting demographic performance which would support the hypothesis that LBAM might currently be in the process of diversification throughout the area surveyed, as a consequence of environmental changes resulting from European settlement.General inferences are drawn from the present findings, concerning feasible objectives and procedures for the practical study of pest insects.
Replacement interaction diagrams in interspecific competition experiments
Authors: WILDIN J. H. , HALL R. L. 
Published: July 2006

Abstract Replacement interaction diagrams offer a new approach in displaying results of interspecific competition experiments. They allow visual assessment of both actual and relative responses of two species in a replacement series to treatments arranged in a factorial array. Yield data are plotted on a semi‐logarithmic scale along the vertical axis. Treatments are arranged on the horizontal axis.The degree of interspecific interference or competition in mixed populations is best assessed by comparing the species response in a mixture with that in the monoculture. In competition experiments involving a number of treatment variables, replacement interaction diagrams highlight trends in treatment responses and allow some comparisions of responses between plant frequences.
The ecology of Araucaria species in New Guinea. III. Population dynamics of sample stands
Authors: ENRIGHT N. J. 
Published: July 2006

AbstractLife table data for A. cunninghamii and A. hunsteinii from a total of four sites near Bulolo, Papua New Guinea are presented. Sample populations are analysed using the Leslie matrix method. Values of λ, the ‘finite rate of natural increase’, vary between sites and species in the predicted manner. The value of λ calculated for the A. cunninghamii population is close to, and slightly above 1.0, while the three values calculated for A. hunsteinii show wide variation, with values both above and below 1.0. It is argued that A. hunsteinii is a gap regenerating species and cannot regenerate beneath a closed canopy. Evidence presented here and elsewhere indicates that A. cunninghamii is more shade tolerant and therefore, theoretically, better adapted to stable forest situations.
Soil requirements of central Australian sandridge plants in relation to the duneswale soil catena
Authors: BUCKLEY R. 
Published: July 2006

AbstractThe soil requirements of seven central Australian sandridge plant species were examined by comparing the soils associated with individuals of each species in their typical sandridge habitats and in anomalous habitats such as dry watercourses, grader banks on road verges, disturbed ground near boreholes, and sand‐filled rock crevices.The species studied were Zygochloa paradoxa, Chamaesyce wheeleri, Calotis erinacea, Helichrysum ambiguum, Dampiera cinerea, Triodia basedowii and Monachather paradoxa.The first two of these are characteristic of open dunecrests, the next three of crests and upper dune slopes, and the last two of lower slopes and swales. The first five species grow in a range of anomalous habitats with nutrient status comparable to swales and lowerslopes, but only if the soils are loosened or have enhanced moisture status. The deep wellsorted sands of dry watercourses form the only anomalous habitat for Zygochloa paradoxa and Chamaesyce wheeleri. Calotis erinacea, Helichrysum ambiguum and Dampiera cinerea also grow on poorly sorted graderbank and borehole soils in the swales, but not on unmodified swale soils. The only anomalous habitats in which the last two have been found are very similar to their typical sandridge habitats and so reveal little of soil requirements.
Floristic composition and structure of a rainforest area 25yr after logging
Authors: KING G. C. , CHAPMAN W. S. 
Published: July 2006

AbstractIn 1949 an area of undisturbed warm temperate rainforest (simple notophyll vine forest) in mid‐north coastal New South Wales, Australia was studied in terms of both floristics and structure (Burges A. & Johnston R. D. J. Ecol. 41, 72‐83, 1953).During 1955‐56, the area in which the transect was located was logged. Over 90% of the upper closed canopy trees adjacent to the creek and on the lower slope and about 35% of canopy trees on the upper slope were removed.The area was reassessed in terms of floristics and structure in 1981. The greatest impact of logging in the study area was structural and largely confined to the flat adjacent to the creek and to the lower slope. With the exception of the remaining gaps covering 6% of the area, structural recovery time is estimated at 140‐190 yr. In the gaps structural recovery may take up to 250 yr.All flowering plants, ferns and mosses previously recorded were present 25 yr after logging. The two alien plant species on the site are short lived intolerant species and gradually disappearing with canopy closure of the regenerating forest.The regeneration of the original tree species is healthy and vigorous with most regeneration resulting from the growth of advance regeneration present at the time of logging or the germination of new seedlings. Eleven per cent of the regeneration is attributable to coppicing. The importance of remnant canopy trees as a source of propagules for the trees and epiphytes is recognised. The larger openings are slower to recover as a result of lack of protection from frost. The stability of floristic composition of this area of warm temperate rainforest following heavy logging is demonstrated.
Water stress, leaf nutrients and defoliation: a model of dieback of rural eucalypts
Authors: LANDSBERG J. , WYLIE F. R. 
Published: July 2006

AbstractWater stress, concentrations of foliar nutrients and damage of foliage by insects were studied over an eleven month period, for eight dieback eucalypts and eight closely matched healthy trees growing in close association on two grazing properties near Brisbane. Four healthy eucalypts in a neighbouring State Forest were also studied. The study region had suffered severe climatic stress between 1972 and 1976 when dieback was first observed by residents and when high populations of defoliating insects were observed. Dieback trees had a higher proportion of foliage damaged by insects and higher concentrations of foliar nutrients than did matched healthy trees. The study period was one of low climatic stress during which dieback and healthy trees followed similar seasonal patterns of predawn xylem pressure potential. Dieback trees developed lower daytime minimum xylem pressure potentials than did matched healthy trees, and differed in their stomatal responses. A model of initiation and development of rural eucalypt dieback is proposed. This may have general application to many non‐specific rural diebacks in which heavy insect damage is implicated. The balance between rural eucalypts and their insect herbivores is precarious. Any factor capable of causing extensive defoliation, or an increase in foliar nitrogen, or an increase in populations of insect herbivores may upset this balance. A positive feedback loop may be activated, whereby the production of nitrogen rich epicormic foliage enhances a build up of insect populations. Repeated insect defoliation leads to tree dieback. Evidence in the literature supporting the model is reviewed and aspects requiring further research are outlined.
Changes in the composition of understorey vegetation after harvesting eucalypts for sawlogs and pulpwood in East Gippsland
Authors: LOYN RICHARD H. , FAGG PETER C. , PIGGIN JOSEPHINE E. , MORTONKEVIN ANN G. , TOLHURST G. 
Published: July 2006

AbstractCover and abundance of all understorey vascular plant species were studied on permanent plots on two areas (Maramingo and Reedy Creek) in the foothill forests of East Gippsland, eastern Victoria. The areas were harvested for sawlogs and pulpwood in 1976, and parts were burned to assist regeneration. Plots were assessed before harvesting and at intervals until 1980. Changes in total species composition were minimal, although there were many positive and negative changes in crown cover and abundance of individual species. Total cover of understorey vegetation was reduced initially but recovered well on both areas. By 1980, cover at Maramingo was slightly greater than the low levels before harvesting. Some species there were favoured by burning while others were not. At Reedy Creek the original dense understorey had not regenerated fully by 1980. Snig tracks had revegetated to 60% of original average cover but log landings were slower to revegetate. Introduced species were initially a very minor component of the vegetation on both areas: they remained so at Reedy Creek (confined mainly to tracks) but at Maramingo three species proliferated along with other small herbaceous plants.
Rainforest—eucalypt forest interactions and the relevance of the biological nomad concept
Authors: SMITH J.M.B. , GUYER I.J. 
Published: July 2006

AbstractTransects across the margins of rainforests with eucalypt forests at two sites in New South Wales are described. At Girard State Forest along ten transects it was consistently found that pure rainforest occurs where there is no evidence of past burning; and that rainforest tree species appear to be invading and replacing eucalypt forest through a formerly burned ecotone area. A similar pattern was found at Barrington Tops. It is suggested that adaptations shown by species of tall open forests which enable them to regenerate rapidly after burning may have evolved initially in a fire free, prehuman rainforest environment in response to other types of disturbance.
The kwongan (sclerophyllous shrublands) of Tutanning Nature Reserve, Western Australia
Authors: BROWN J. M. , HOPKINS A. J. M. 
Published: July 2006

AbstractKwongan is an important vegetation type in southwestern Australia. It occurs in small patches throughout Tutanning Nature Reserve. Eleven patches, totalling 64 ha, were found to contain 315 vascular plant species: over half the total species recorded for the whole reserve. The patches were floristically heterotoneous (cf. Westhoff & van der Maarel 1973) but could be grouped according to three major soil types. The richest kwongan was on pockets of shallow duplex soil occurring midway down the landscape profile. Species richness appears to decline only slightly with increasing time since fire. Presence of emergent Banksia attenuata at one site did not influence the overall speciesrichness of that area.
An extension of the Leslie matrix model to include a variable immature period
Authors: LONGSTAFF BARRY C. 
Published: July 2006

AbstractAn extension to the Leslie matrix is presented in which the age of transformation from immature to adult has a log—normal distribution. The major effect of this is shown to be on the second largest eigenvalue. The ratio of the largest to the second largest eigenvalue |λ1/λ2|, which is an index of the rate of approach to the stable age distribution, is greater in the new model, even though the value of λ1 is effectively the same. The differences in the models are most pronounced where the population is subjected to a harvesting regime.
Effects of fire on central Australian rangelands. II Changes in tree and shrub populations
Authors: GRIFFIN G. F. , FRIEDEL M. H. 
Published: July 2006

AbstractThe effect of a summer fire or a winter fire on tree and shrub populations in two rangeland vegetation types in central Australia was investigated. Changes in population structure of two major species occurred regardless of the season of burn. The decrease in overall density of Acacia aneura, Eremophila gilesii and Cassia spp. was similar for summer and winter fire treatments: greater reduction of E. latrobei followed the summer burn.Higher fire line intensity caused greater mortality in all species but enhanced germination in A. aneura, a potentially ‘weedy’ species. Winter fires appear to be preferable for management of woody plants in the particular vegetation types studied.
Inter‐tree competition and small‐scale pattern in monoculture ofEucalyptus obliquaL'Herit
Authors: WEST P. W. 
Published: July 2006

AbstractThe pattern of spatial arrangement of trees at scales up to 20 m is examined in 12 plots of even‐aged monoculture of tall‐openEucalyptus obliquaL'Herit. forest, aged 30–57 years, in Tasmania. In general, trees were randomly arranged on the plots. In four plots there was a tendency towards regular spacing amongst the 50% largest diameter trees of the plots, these trees being the more successful competitors. There was evidence that this occurred simply because crown spread prevents dominant trees being too close together. There were slight tendencies in some plots for larger trees to be further from their nearest neighbouring tree than smaller trees and to have smaller nearest neighbours than smaller trees. These results are considered in relation to suggestions that competition in monoculture should impose spatial regularity on successful competitors and that dominant trees suppress near by trees. It is suggested that inter‐tree root grafting or variability in the shape of root and crown systems may reduce the tendency for these effects to apply, consistent with the results of the present work.
Ecological studies on Thrips imaginis Bagnall (Thysanoptera) in flowers of Echium plantagineum L. in Australia
Authors: KIRK W. D. J. 
Published: July 2006

AbstractAspects of the ecology of Thrips imaginis Bagnall in flowers of Echium plantagineum L. are described and subjected to experimental analysis.Thrips eggs were mostly laid in plant parts that were not lost when the short‐lived flowers abscissed. The abundance of adults and larvae in flowers from the bud stage through to abscission was determined. Larvae usually required more than one flower to complete development and so had to migrate between flowers to survive. Larvae generally remained between the bases of the stamen filaments when in direct sunlight, but moved along the filaments to the anthers for rapid pollen feeding during low light intensity, especially at night. There was little spatial and temporal overlap between thrips larvae and honeybees in the flowers. Ants can cause much damage to the flowers and can feed on thrips.Pollen feeding of T. imaginis is described. The species of pollen grain affects feeding, and this may influence breeding success.Low u.v.‐reflecting white, blue and yellow water traps caught more T. imaginis that green, red, black and high u.v.‐reflecting white. These results agree well with the numbers of adults in several native and non‐native flowers of various colours.Adult female thrips colour variation is correlated with for ewing length, and hence reflects factors acting on a pre‐adult stage.