bluuebunny/crossref_metadata_2025 huggingface dataset:
Seed supply as a limiting factor for granivorous bird assemblages in the Monte Desert, Argentina
Authors: Blendinger Pedro G. , Ojeda Ricardo A.
Published: March 2003

Seed availability may limit the size of granivorous bird populations, particularly in desert environments. Seasonal and annual fluctuations in the abundance of granivorous birds were studied at three sites in the Northern Monte Desert, Argentina. The way in which these changes were related to seed supply was also studied. Granivore abundance and biomass, as well as seed abundance, were greater in winter. Changes in total granivore abundance were mostly because of variations in numbers of the most mobile bird species, all of which were found to have similar patterns of variation in their abundance. Evidence suggests that during the non‐breeding season, the most mobile species are able to track patches of high seed availability over long distances, whereas the abundance of less vagile species largely depends on the local ecological conditions. Seed supply is a proximate factor that limits the abundance of granivorous birds in the Monte Desert during the winter, but does not limit species richness. Granivore abundance was not correlated with seed supply in spring.
Nutrient accessions in a mixed conifer–angiosperm forest in northern New Zealand
Authors: Enright N. J.
Published: March 2003

Nutrient accessions in litterfall are described for a mixed conifer (mostly Agathis australis D.Don (Lindl.), New Zealand kauri) and angiosperm temperate forest in northern New Zealand to determine the relative contributions to nutrient cycling of the conifer and angiosperm components of the forest. Concentrations for many nutrients were significantly lower in conifer litterfall fractions than for equivalent angiosperm fractions. Angiosperm leaves had concentrations of N and P twice those found in conifer leaf fall. Despite a large contribution to litterfall from weight, conifer reproductive parts (mostly cone scales) were very low in nutrients (especially N, P and Ca). Whereas angiosperm litterfall constituted < 45% of total litterfall by weight, nutrient accessions from the angiosperm component accounted for 45–60% of total nutrient accessions and the conifer fraction for only 30–45%, almost the exact reverse of their contributions to litterfall by weight. Of the macronutrients, P (3 kg ha–1 year–1) showed the lowest rate of accession in litterfall while Ca (84 kg ha–1 year–1) showed the highest. Faunal detritus, although < 1% of total litterfall by weight, contributed 10% of total P and 4% of total N reaching the forest floor via the litterfall pathway each year. The C:N and C:P ratios in litterfall and litterstore were all well above the levels at which mineralization is likely to occur. Based on the estimated residence times, long‐term immobilization was more likely for N than for P. The annual pattern of nutrient accessions differed for the two components, with angiosperm accessions highest in spring and summer, and conifer accessions highest in autumn, due largely to a peak in litterfall of reproductive parts at that time of year. It is argued that differences in litter quality, decomposition rates and spatial and temporal patterns of litterfall for angiosperm versus conifer components of the forest, in conjunction with long‐term disturbance regimes, may contribute to conifer–angiosperm coexistence.
Insect damage in Eucalyptus: A review of plantations in Chile
Authors: Lanfranco D. , Dungey H. S.
Published: March 2003

Chile has more than 330 000 ha of eucalypt plantations, predominantly in the eighth to the tenth region (approximately 34 to 41°S). Eucalyptus globulus ssp. globulus is the principal eucalypt planted, but Eucalyptus nitens, Eucalyptus camaldulensis, Eucalyptus delegatensis and Eucalyptus viminalis are also grown. There are four main insect pests that have been detected attacking these eucalypts in Chile: the defoliator Gonipterus scutellatus, the bark borers Phoracantha semipunctata and Phoracantha recurva and the native wood borer Chilecomadia valdiviana. More recently, Thyrinteina arnobia and Ctenarytaina eucalypti have been detected. Gonipterus scutellatus and P. recurva have been discovered in Chile within the last 2 years and it is hoped they may still be eliminated using a combination of biological control and chemical control of local populations. Phoracantha recurva and P. semipunctata are not considered a problem because attack only occurs in areas of water deficit, away from current eucalypt plantations. Chilecomadia valdiviana can damage plantations of E. nitens but rarely attacks other eucalypts.◊Chilecomadia valdiviana may cause future problems through further host shifts. Thyrinteina arnobia has only been detected during quarantine surveillance in the port of Valparaiso. Ctenarytaina eucalypti, recently detected in August 1999, had an initial limited distribution in the first region. However, since then, this insect has expanded its distribution south up to the tenth region. None of the insects recorded on eucalypts in Chile to date currently presents a threat to the eucalypt industry. It is also essential that additional resources are made available for their continued monitoring and control, particularly given that the 44% of plantations are held by small to medium property owners that would otherwise be unable to control a serious outbreak because of economic restrictions.
Insect herbivory and ontogeny: How do growth and development influence feeding behaviour, morphology and host use?
Authors: Hochuli Dieter F.
Published: March 2003

Herbivorous insects exploit many different plants and plant parts and often adopt different feeding strategies throughout their life cycle. The conceptual framework for investigating insect–plant interactions relies heavily on explanations invoking plant chemistry, neglecting a suite of competing and interacting pressures that may also limit herbivory. In the present paper, the methods by which ontogeny, feeding strategies and morphological characters inhibit herbivory by mandibulate holometabolous insects are examined. The emphasis on mechanical disruption of plant cells in the insect digestive strategy changes the relative importance of plant ‘defences’, increasing the importance of leaf structure in inhibiting herbivory. Coupled with the implications of substantial morphological and behavioural changes in ontogeny, herbivores adopt a range of approaches to herbivory that are independent of plant chemistry alone. Many insect herbivores exhibit substantial ontogenetic character displacement in mandibular morphology. This is tightly correlated with changes in feeding strategy, with changes to the cutting edges of mandibles increasing the efficiency of feeding. The changes in feeding strategy are also characterized by changes in feeding behaviour, with many larvae feeding gregariously in early instars. Non‐nutritive hypotheses considering the importance of natural enemies, shelter‐building and thermoregulation may also be invoked to explain the ontogenetic consequences of changes to feeding behaviour. There is a need to integrate these factors into a framework considering the gamut of potential explanations of insect herbivory, recognizing that ontogenetic constraints are not only viable explanations but a logical starting point. The interrelations between ontogeny, size, morphology and behaviour highlight the complexity of insect–plant relationships. Given the many methods used by insect herbivores to overcome the challenges of consuming foliage, the need for species‐specific and stage‐ specific research investigating ontogeny and host use by insect herbivores is critical for developing general theories of insect–plant interactions.
Pollination and fruit‐set of Grevillea robusta in western Kenya
Authors: Kalinganire A. , Harwood C. E. , Slee M. U. , Simons A. J.
Published: March 2003

The floral visitors of silky oak, Grevillea robusta A. Cunn. ex R.Br., their foraging behaviour and their effects on fruit‐set were studied at Malava, western Kenya. Grevillea robusta is a popular tree for farm plantings in the eastern and central African highlands. Yield of seed has been disappointingly low in some areas and a lack of appropriate pollinators has been suggested as a possible cause. Investigations involved the monitoring of visitors on active inflorescences, assessment of the rewards available to potential pollinators, and exclusion experiments to establish the effects of various visitors on fruit‐set. The flowers are visited mainly by birds and insects. The likely pollinators of G. robusta are sunbirds (Nectarinia amethystina, N. cyanolaema, N. olivacea, N. superba and N. venusta) and white‐eyes (Zosterops kikuyuensis and Z. senegalensis). Very little aggressive behaviour between birds was recorded. No nocturnal pollinators were observed. Nectar was the major floral reward for pollinators, but is likely depleted by ants and honey bees, the foraging behaviour of which confirmed them to be nectar‐robbers. These insects hardly ever touched stigmas during their visits. Eighty‐nine per cent of bird visits were in the morning (07.00–10.00 hours) when nectar volume was highest. Inflorescences bagged to exclude birds set no fruits, and unmanipulated flowers and flowers bagged with self‐pollen set no fruits, indicating a self‐incompatibility mechanism. Control cross‐pollinated flowers displayed greatly increased fruit‐set (25.1%) compared with natural open‐pollination (0.9%). All these findings confirm the importance of cross‐pollen transfer to flowers and the necessity of pollinators for fruit‐set. Effective seed production requires activity of pollinators for self‐pollen removal and cross‐pollen deposition. Seed production stands for G. robusta should be established where flowering is prolific and bird pollinators are abundant.
Colonization of eucalypts in New Zealand by Australian insects
Authors: Withers T. M.
Published: March 2003

Since the 1860s, Australian insects have steadily colonized eucalypts in New Zealand. The rate of colonization has increased markedly over the last two decades. This increase may be related to increasing trade between the two countries. Currently there are 26 specialist eucalypt insect species and approximately 31 polyphagous insect species that can feed on Eucalyptus in New Zealand. The specialist eucalypt insects endemic to Australia have generally caused more damage than polyphagous or native insects. Eucalypt‐specific insects are dominated by sap sucking bugs, particularly psyllids, and defoliating Coleoptera and Lepidoptera. In some cases the major insect pest species have been those that are only occasional pests in Australia, for example Gonipterus scutellatus, Ctenarytaina eucalypti, Eriococcus coriaceus and Phylacteophaga froggatti. Some important insect pests have been rare, or even not described from Australia, prior to their appearance as a pest in New Zealand, for example Paropsis charybdis and Ophelimus eucalypti. Invading eucalypt insects are more likely to establish in the Auckland region than anywhere else in New Zealand.
What physiological processes permit insects to eat Eucalyptus leaves?
Authors: Cooper Paul D.
Published: March 2003

Many species of insects eat Eucalyptus foliage despite its relatively low nutritional value and the many plant secondary metabolites (PSMs) present, for example, terpenes, phenols and formylated phloroglucinols (FPGs). Formylated phloroglucinols are a new class of PSMs that act as antifeedants for possums and koalas. What physiological processes are present that permit insects to eat eucalypt foliage and how do PSMs influence insect feeding or digestion? Some trees seem to be repeatedly infested with eucalypt‐feeding insects, possibly as a result of previous chemosensory cues remaining from parental selection of a plant. Avoidance or storage of PSMs permit jarrah leafminers (Perthida glyphopa) and sawflies (Perga sp.) to consume eucalypt foliage without dealing with the majority of these compounds. Some PSMs can be metabolized by polysubstrate membrane oxidases as found in caterpillars or sawflies that feed on eucalypts. High midgut pH may be advantageous for nutrient extraction and PSM metabolism, and midgut pH ranges between 8.5 and 8.9 for caterpillars of Hyalarcta huebneri. Plant secondary metabolites may not be absorbed as a result of the combined presence of the peritrophic matrix and endogenous surfactants. Excretion of PSMs can be as metabolites or intact compounds. Both putative metabolites and sideroxylonal‐A, an FPG, are present in the faeces of larvae of the case moth, H. huebneri. The presence of sideroxylonal‐A in the food had an effect on the presence of 5‐hydroxytryptamine (5HT) in the central nervous system of caterpillars, as larvae fed leaves with a high concentration of sideroxylonal‐A had relatively more 5HT in the brain and central nervous system ganglia than larvae fed leaves containing a low concentration. Further work is necessary to clarify how PSMs are handled by eucalypt‐feeding insects and what effect FPGs have on feeding and digestion.
Influence of previous frost damage on tree growth and insect herbivory of Eucalyptus globulus globulus
Authors: Thomson Vivien P. , Nicotra Adrienne B. , Steinbauer Martin J.
Published: March 2003

The plant stress hypothesis suggests that some herbivores favour stressed plants, whereas the plant vigour hypothesis proposes that other herbivores prefer vigorous plants. The effects of a prior stress, that of frost damage, were examined on the subsequent growth of Eucalyptus globulus globulus and on the response of insect herbivores. Frost damage affected tree growth by reducing new leaf area and increasing specific leaf area (SLA). However, herbivore abundance was not affected by prior frost damage. Two feeding trials using Anoplognathus chloropyrus and Hyalarcta huebneri and a morphometric study of Ctenarytaina eucalypti were conducted to assess the performance of herbivores on trees that had suffered more or less frost damage. Consumption by A. chloropyrus and H. huebneri was unaffected by foliage origin (damaged versus healthy). Hyalarcta huebneri grew faster when fed leaves from previously damaged trees, and C. eucalypti from previously damaged trees were larger than those from healthy trees. Enhanced insect performance on frost damaged plants may have resulted from the high specific leaf area (most likely thinner) leaves. The herbivore abundance data did not support the hypothesis that previously frost damaged plants are preferred by insects. However, increased growth of H. huebneri and larger body size of C. eucalypti on damaged trees indicates that previously stressed trees may produce leaves of higher nutritional value.
Feeding ecology of a carnivorous bladderwort (Utricularia uliginosa, Lentibulariaceae)
Authors: Jobson Richard W. , Morris E. Charles
Published: March 2003

The terrestrial carnivorous bladderwort, Utricularia uliginosa Vahl. (Lentibulariaceae) was studied to determine the species assemblage present in traps of these plants in situ across four sites over 15 months. The immediate soil environment was also sampled to determine the fauna present, and to compare the fauna present in traps with the fauna in the environment. The soil fauna consisted of 10 taxon types, which occupied either pelagic, epibenthic or interstitial microhabitats. All were found in traps of U. uliginosa, with the main prey being interstitial taxa followed by epibenthic and occasionally pelagic taxa. Numbers of individuals of the two most abundant soil taxa (nematodes, Elaphoidella) varied independently across the four sites over the 15 months of the study, as did numbers of Elaphoidella in the traps of U. uliginosa. Numbers of nematodes in the traps of U. uliginosa showed significant differences among sites, but not differences among times. Comparison of the trap fauna with the soil fauna revealed differences in relative abundance between soil samples and trap samples for two of the three taxa examined. There was an under‐representation of nematodes in the traps relative to numbers in surrounding soil. There was an over‐representation of the copepod Elaphoidella in the traps of U. uliginosa relative to numbers in soil at some of the times of sampling. Acarina were equally abundant in soil and trap samples. The patterns observed for Elaphoidella and nematodes may be due to selectivity in trapping by U. uliginosa, and/or differences in digestibility of the prey. Elaphoidella individuals were found to be attracted to U. uliginosa in a behavioural experiment. This may contribute to the over‐representation of Elaphoidella in the traps of U. uliginosa in the field.
Effects of frequent fires and grazing on stable nitrogen isotope ratios of vegetation in northern Australia
Authors: Cook G. D.
Published: March 2003

The ratios of stable nitrogen isotopes expressed as δ15N values can indicate the openness of nitrogen cycles in ecosystems. Southwards through the Northern Territory, values of foliar δ15N in savanna trees increase as mean annual rainfall decreases from approximately 1800 mm to approximately 750 mm, with foliar δ15N thereafter decreasing toward arid central Australia. Recent literature argues that this pattern is caused by higher grazing intensity in semi‐arid savannas, but counter views have attributed the pattern more directly to variations in aridity. In this paper, grazed and ungrazed sites in a semi‐arid savanna are compared, and it is shown that grazing has a relatively small effect on the positive foliar δ15N values of grasses, but no effect on δ15N values of trees. This gives little support to the argument that variations in grazing pressure at the scale of hundreds of kilometres could result in detectable differences in the foliar δ15N values of trees. I then compare the semi‐arid savannas with mesic savannas, where fires are frequent, and with mesic rainforests, which are rarely burnt. Greater foliar δ15N values in rainforest and fire‐excluded mesic savannas than in frequently burnt savannas suggests that fire regimes affect foliar δ15N. The previously observed pattern in δ15N values along the rainfall gradient in the Northern Territory is consistent with trends in fire frequency and possible direct effects of fire, but further work is required to determine the relative impacts of aridity and fire. Within a particular rainfall regime, foliar δ15N values may indicate historical fire frequencies.
Measurement of leaf biomechanical properties in studies of herbivory: Opportunities, problems and procedures
Authors: Sanson G. , Read J. , Aranwela N. , Clissold F. , Peeters P.
Published: March 2003

Leaf biomechanical properties have the potential to act as antiherbivore defences. However, compared with studies on chemical defences, there are few studies that have demonstrated that the physical or biomechanical structure of plants can prevent or influence herbivory. This difference in focus by ecologists may relate to the dominant paradigm of plant chemical defences in ecological research and the perceived difficulties that ecologists have with the engineering principles embedded in biomechanics. The advantage of using materials engineering concepts is that each property is precisely defined and quantifiable, although the latter may be difficult in leaves because of their composite and anisotropic nature. Most herbivory studies have used simple penetrometers to measure leaf properties, often termed ‘toughness’. As defined in materials engineering, the measured properties are ‘force to fracture’ and ‘strength’, not toughness. Measurement of strength, the resistance to crack initiation, is relevant to understanding herbivory. Measurement of ‘toughness’ as defined by materials engineering is also relevant. Toughness is the resistance to crack propagation and is a measure of the energy required to fracture the leaf. This requires more sophisticated equipment than simple penetrometers because it requires a simultaneous measure of the punch displacement. In addition, purists would argue that a punch cannot be used to measure true toughness because the crack is not controlled and plastic deformation is also involved. However, it may be the only method that allows detection of fine‐scale pattern in mechanical properties across a leaf surface at a scale that is relevant to herbivory. There is very little work on the scale at which these properties vary, particularly with regard to different sized herbivores. In addition, few studies have investigated a broad range of relevant biomechanical properties in relation to herbivory. Therefore, it is not possible yet to be definitive about the relative merits of the various types of tests. A single test might show a pattern in relation to herbivore damage at a gross level. However, to really understand the functional and ecological significance of leaf texture in relation to herbivory, a more reductionist approach is needed. Only then can we move on to the larger scales of pattern that many ecologists are seeking.
Ecological biogeography of species of Gelonus, Acantholybas and Amorbus in Australia
Authors: Steinbauer Martin J. , Yonow Tania , Reid Ian A. , Cant Russell
Published: March 2003

Geographic ranges and host plants of 10 species of Australian coreid, Gelonus
tasmanicus, Acantholybas brunneus, Amorbus alternatus, Am. atomarius,
Am. biguttatus, Am. bispinus, Am. obscuricornis, Am. rhombifer,
Am. robustus and Am. rubiginosus, were summarized using data from specimen
collection labels and sampling. One process (CLIMEX) and two correlative
range‐modelling programs (BIOCLIM and DOMAIN) were
used to infer the bioclimatic profiles of each species. By inference from the maximum
range predictions made by CLIMEX, the suggestion that G. tasmanicus,
Am. atomarius and Am. obscuricornis are temperate species was supported.
Similarly, the suggestions that Ac. brunneus was a subtropical species and
Am. biguttatus and Am. rhombifer are predominantly tropical species
were supported. That Am. alternatus, Am. robustus and Am. rubiginosus
are apparently ubiquitous species was supported. Comparison of the bioclimatic profiles
of the habitats of G. tasmanicus and Am. obscuricornis within Tasmania
using BIOCLIM supported information available in the published literature,
that is, that G. tasmanicus is better suited to sites at higher elevations
than Am. obscuricornis. In addition, the suggestion that the regions of high
Amorbus species endemism should overlap with regions of high eucalypt species
endemism was also supported. This finding is taken as evidence that the evolutionary
radiation of Amorbus has followed that of the eucalypts. Using these models we have obtained preliminary insights into the biology of each species and the environmental characteristics of their preferred climatic envelope. This is an achievement that might never have been attained through concentrated study given that these insects can vary from being rare to, at best, locally common in occurrence.
The late Quaternary vegetation history of the south‐central highlands of Victoria, Australia. II. Sites below 900 m
Authors: McKenzie G. Merna
Published: March 2003

The late Quaternary vegetation communities of the south‐central highlands of Victoria are constructed from analyses of pollen and charcoal, and macroscopic plant remains preserved inSphagnumbogs. The sites, located in eucalypt forest or woodland, form an altitudinal sequence with the componentEucalyptusspecies varying with altitude and with small pockets ofNothofagus cunninghamii(Hook.) Oerst. in close proximity to the higher sites. The record from the sites above 900 m covers the last 32 000 years, and the record from the lower sites extends from at least 12 000BP. Around 32 000BPthe region was predominantly covered by a mosaic of alpine feldmark and herbfield, with small patches ofEucalyptusandNothofaguswoodland close to sea level when summer temperatures were probably 5°C lower than present. Lowest values, probably 7°–8°C below present, occurred between 19 800 and 16 900BP, when alpine communities were most widespread and much of the Central Highlands was treeless. Around 12 000BPalpine taxa disappeared or were greatly reduced, first at the lower sites. There was an associated rise in the treeline with the movement upslope ofNothofagusand eucalypt forest as a result of a general increase in temperature and probably effective precipitation. By 6000BPwet eucalypt forest andNothofagusreached their maximum postglacial extent at all sites, possibly related to a further increase in temperature, at least 2°C lower than present, and higher effective precipitation. A continuing increase in temperature, or an increase in continentality, and a decrease in effective precipitation led to increased fire hazard and retraction of rainforest and wet sclerophyll or tall open forest toward present‐day values.Nothofagusdisappeared from the sites below 900 m. The activities of humans pose further threats to remaining forest communities. The record of vegetation and environmental change derived from the local and regional picture from eight sites reinforces and complements that from the individual sites. For example, combining the records overcomes to some extent taphonomic problems such as the effect of streams that flow close to all sites, and other limitations including problems of dating, poor preservation and variable sedimentation rates.
Comparison of two rolled sandy heath communities within a single fire patch in Ngarkat Conservation Park, South Australia
Authors: Pelton Grant A. , Conran John G.
Published: March 2003

Cross‐ribbed rolling is a technique routinely used to construct firebreaks along the margins and access tracks of Ngarkat Conservation Park, South Australia. These breaks, approximately 20 m wide, contain regenerating heath communities with an overstorey of mallee. The effects of cross‐ribbed rolling on community composition and succession were examined in a single fire patch on the western boundary of Ngarkat Conservation Park across 12 sites located in vegetation burnt approximately 35 years ago. Two areas at each site were investigated, one on rolled communities and the other running parallel on the adjacent unrolled vegetation. There was also a difference in the rolled communities sampled; six were on a 3‐year‐old break, whereas the remainder were on a 5‐year‐old break. Results indicate no changes to species richness or diversity when comparing rolled and unrolled areas, but there was some alteration to species composition in rolled communities. These results suggest that under current rolling regimes, the main effect is a reduction in biomass and some accompanying alteration to species composition, but not a reduction in overall species diversity or an increase in weeds.
Sexual divergence in diets and morphology in Fijian sea snakes Laticauda colubrina (Laticaudinae)
Authors: Shetty S. , Shine R.
Published: March 2003

In the Fiji Islands, female yellow‐lipped sea kraits (Laticauda colubrina) grow much larger than males, and have longer and wider heads than do conspecific males of the same body length. This morphological divergence is accompanied by (and may be adaptive to) a marked sex divergence in dietary habits. Adult female sea kraits feed primarily on large conger eels, and take only a single prey item per foraging bout. In contrast, adult males feed upon smaller moray eels, and frequently take multiple prey items. Prey size increases with snake body size in both males and females, but the sexes follow different trajectories in this respect. Female sea kraits consume larger eels relative to predator head size and body length than do males. Thus, the larger relative head size of female sea kraits is interpreted as an adaptation to consuming larger prey items. Our results are similar to those of previous studies on American water snakes (natricines) and Australian file snakes (acrochordids), indicating that similar patterns of sex divergence in dietary habits and feeding structures have evolved convergently in at least three separate lineages of aquatic snakes.
Correlation of burning and grazing indicators with composition of woody understorey flora of dells in a temperate eucalypt forest
Authors: Henderson Meredith K. , Keith David A.
Published: March 2003

Abstract
Areas of warm temperate eucalypt forests of northern NSW escarpment, previously managed for cattle production, have recently been transferred into the conservation reserve system. The forests were seasonally grazed by cattle and were burnt frequently to promote green pick for stock feed. The hypothesis that disturbances associated with previous management had led to a simplification of the forest understorey, particularly a depletion in the density and species richness of shrubs was investigated. A disturbance history of the study area was constructed by compiling fire history records and using surrogate measures for recent and historical grazing. Shrub species composition was sampled in randomly located quadrats in dells within the forest, with a set of environmental and spatial covariables. Variation in shrub composition was partitioned among three sources (disturbance, environment and space) using a stepwise canonical correspondence analysis. Grazing and burning disturbance explained substantially more variation in vegetation than the environmental and spatial variables combined. Between 15 and 45% of total variation in adult shrub composition was attributable to the disturbance indicators. Similar results were obtained for composition of juvenile shrubs. Species richness and population densities of woody species were lower where disturbance was more intensive. It is concluded that historical grazing and burning practices had a substantial impact on the woody understoreys of the north‐east escarpment forests. The species that were adversely affected spanned a range of life‐history functional types. Estimates of the magnitude of grazing and burning impacts were limited by the lack of spatially explicit disturbance history data over the full period of pastoral exploitation and the unavailability of suitable ungrazed‘controls’for sampling.
Macrofungal diversity and community ecology in mature and regrowth wet eucalypt forest in Tasmania: A multivariate study
Authors: Packham J. M. , May T. W. , Brown M. J. , Wardlaw T. J. , Mills A. K.
Published: March 2003

Abstract
The biodiversity of macrofungi in mature and young regrowth Tasmanian wet forests is described at the species level and at the community level. The macrofungal communities studied were much more species‐rich than their vascular plant counterparts, with the total number of macrofungal taxa outnumbering vascular plants by four to one. This ratio applied in both mature and young regrowth forest sites. Some 242 taxa of macrofungi were recorded, of which 132 were identified to species level, the remainder to species groups or higher taxa. Distinct communities could be discerned from multivariate analysis (ordination and classification) of vascular plant and macrofungal data from the mature and regrowth sites. The two vascular plant communities had different fire histories, and this difference is also assumed to account for the separation of the macrofungal communities of the two forest types. There was generally a high level of congruence between the vascular plant and the macrofungal communities. However, one young regrowth site, which was relatively close to the mature sites in the ordination space for the analysis of vascular plants, was distant from the mature forest sites for the analysis of macrofungi. Another regrowth site, which had experienced wildfire rather than silvicultural regeneration, clustered with mature sites for some analyses of the macrofungal assemblage. Variation in the macrofungal communities was correlated with a different set of the measured environmental variables than was variation in the vascular plant communities. Mature and young regrowth forests were found to have distinctly different macrofungal floras, with approximately 40% of the taxa in each forest type being restricted to that type of site. Suitable indicator taxa (restricted or preferential to particular forest types) for use in further studies are suggested.
Litterfall and forest floor dynamics in Eucalyptus pilularis forests
Authors: Turner John , Lambert Marcia J.
Published: March 2003

Abstract
Calculations relating the input of litterfall to litter or forest floor mass in forests generally assume that the forest floor reaches an equilibrium state. Based on this assumption, a decomposition factor (k) can be calculated. In the present paper, this basic assumption is questioned and the implications considered. Data on litterfall and forest floor from blackbutt (Eucalyptus pilularis) regrowth forests and plantations were collated from publications and the authors' studies to evaluate both assumptions and relationships. Blackbutt grows over a wide environmental range but its main distribution is in mild temperate to subtropical conditions. Data were from single‐plot studies, sequential studies and chronosequences in both plantations and native regrowth forests. Stands ranged in age from 3 years to maturity in the case of pure, or almost pure blackbutt stands. The forest floor biomass increased up to 12.3 tha−1 at 33 years of age with no evidence of steady state. Litterfall increased up to 7.8 t ha−1 year−1 and was correlated with crown biomass. Regrowth stands were relatively undisturbed and more than 20 years of age, and litterfall ranged from 4.1 to 11.6 tha−1 year−1 and was correlated with stand basal area. Forest floor mass in regrowth forests was variable between the different aged stands but did not exceed 18 tha−1, and there was no evidence that steady state was achieved. The forest floor mass was related to, and approximately 1.7 times the input of litterfall. Although the assumption of steady state was not valid, a k' factor was estimated that related input to forest floor mass and this was relatively constant across all stands and correlated with generalized environmental data. Although assumptions of forest floor equilibrium cannot be supported for E. pilularis, it still should be possible to predict forest floor mass and decomposition from stand conditions and general environmental data.
Spatial variation in abundance of prey and diet of trumpeter (Pelates sexlineatus: Teraponidae) associated with Zostera capricorni seagrass meadows
Authors: Sanchez‐Jerez P. , Gillanders B. M. , Kingsford M. J.
Published: March 2003

Abstract
The diet of juveniles of Pelates sexlineatus was examined at six estuaries, separated by tens to hundreds of kilometres, and two sites within each estuary, separated by hundreds of metres to kilometres. Fish were collected in Zostera capricorni seagrass meadows along the coast of New South Wales (Australia). Spatial variability in diet was compared with the abundance of prey. Pelates sexlineatus had a broad diet (27 different prey) but generally preferred crustaceans (harpacticoid copepods, gammarid amphipods, ostracods and tanaids), although at some sites other prey items were important (e.g. polychaetes, nematodes and foraminiferans). Composition of the diet varied among estuaries and between sites. Proportional representation of the different size of prey eaten by the three sizes of juveniles (40‐54, 55–74 and 75–94 mm standard length) was similar. Fish generally preferred prey smaller than 1 mm. Abundance of prey also varied at both spatial scales. At five of the 12 sites, there was a significant correlation between abundance of prey in the seagrass meadows and abundance of prey in the diet. Variation in the composition of the diet was partly explained by spatial variation in abundance of prey. When crustaceans were not abundant in the seagrass, P. sexlineatus had a broad diet, taking both benthic and planktonic prey items. It is concluded therefore that trophic linkages between P. sexlineatus and benthic invertebrates may vary greatly with spatial scales from hundreds of metres to hundreds of kilometres, and are strongly related to availability of prey in seagrass habitats.
Patterns of spatial and temporal variation of macrofauna under boulders in a sheltered boulder field
Authors: Chapman M. G.
Published: March 2003

Abstract
Spatial and temporal patterns of abundance of animals and plants must be quantified before models to explain distributions can be developed. These patterns also provide essential data for measuring potential effects of environmental disturbances. Studies in many different habitats have shown that most organisms, particularly invertebrates, have highly variable and interactive patterns of abundance, with much variability at the smallest temporal and spatial scales. Intertidal boulder fields in New South Wales, Australia, support a diverse fauna, many species of which are relatively rare. These habitats are commonly found near rock‐platforms and in sheltered estuaries and are subjected to many human disturbances. Although there have been a few studies on the fauna in boulder fields, none has documented variability of the assemblage using multivariate and univariate techniques and most studies have not incorporated different spatial and temporal scales. This study quantifies spatial variation at three scales (metres, tens of metres alongshore and tens of metres upshore) and temporal variation at two scales (3 months and 2 years) of the assemblage of molluscs and echinoderms in a sheltered boulder field subjected to little natural or human disturbance. Multivariate analyses revealed that each site contained a distinct assemblage, mainly due to the relative abundances of a few species. Most species, those generally only found under boulders and common, widespread species, had considerable spatial variability in abundances, with more than 90% measured at the smallest scale, that is metre to metre within a site. Changes in abundances over 3 months or 2 years varied among species and sites in unpredictable ways. These data show that sampling designs to measure impacts on these fauna will need to be complex and must incorporate a number of spatial and temporal scales if they are to be able to detect impact against such a variable background.
Breeding system and population genetics of the vulnerable plantDillwynia tenuifolia(Fabaceae)
Authors: Rymer P. D. , Morris E. C. , Richardson B. J.
Published: March 2003

Dillwynia tenuifoliaSieber ex DC. is a vulnerable species endemic to the Sydney region in Australia. This investigation focused on the breeding system and genetic structuring of the species in locations encompassing its entire geographical range. A field pollination experiment showed thatD. tenuifoliaproduced fruit from both self‐ and cross‐pollination events, and thus has a facultative breeding system. Fruiting success from self‐ pollination was approximately half that observed from cross‐pollination. The genetic structure ofD. tenuifoliapopulations was investigated by using allozyme electrophoresis. A survey of 16 loci revealed a high level of genetic variation with approximately two‐thirds of the loci being polymorphic and a mean of 1.84 alleles per loci. The genotype frequencies deviated from the Hardy–Weinberg equilibrium, with the observed level of heterozygosity significantly less than expected. The inbreeding coefficient was 0.31. There was very little divergence between populations (FST= 0.04) but the fixation indices were high within populations. Spatial autocorrelation, using Moran’sI, showed that neighbouring plants were closely related (I> 0.4). The genetic neighbourhood and effective population size in the species were estimated at one location as 1.1 ha and 104plants, respectively.
Effects of extra food on population fluctuation patterns of the muroid rodent Calomys venustus
Authors: Castellarini F. , Polop J.
Published: March 2003

Population dynamics in the South American muroid rodent Calomys venustus are described from a 14‐year continuous data series, using the auto‐regressive integrated moving average (arima) model. Population responses to experimental food addition were analysed in two experimental areas, over two periods, using intervention analysis. There was no consistent evidence that food quantity leads to peaks in population density. Significant increases were related to densities of transients and juvenile individuals.
Response of a rare herb (Trioncinia retroflexa) from semi‐arid tropical grassland to occasional fire and grazing
Authors: Fensham R. J. , Fairfax R. J. , Holman J. E.
Published: March 2003

Trioncinia retroflexa (Asteraceae) is a rare perennial herb endemic to Dichanthium‐dominated grasslands on basaltic soils in central Queensland. Trioncinia lives for approximately 5 years and some seed remains viable in the soil for at least 18 months. Population densities increased sixfold over 4 years, coinciding with recovery during a period of above‐average rainfall after a 4‐year drought preceding this study. The species’ lifespan, which can exceed 5 years, coupled with its extended seed‐bank viability ensures that populations can endure drought despite low levels of seedling recruitment. The restricted occurrence of the species to spasmodically grazed stock routes provides evidence that Trioncinia is sensitive to the continuous grazing that typically occurs in paddocks. The hypothesis that the species requires occasional disturbance for survival was experimentally tested. Recruitment was depressed with burning and inflorescence production enhanced with both burning and simulated intense spasmodic grazing after the first application of treatments. However, these effects were not evident after a second application of the treatments and there were no significant effects of treatment on population densities at the completion of the 4‐year experiment. Although not requisite, sporadic dry‐season grazing and burning of these areas would appear to be compatible with the survival of Trioncinia. This project highlights the value of stock routes for rare plant conservation.
Responses of vertebrates to pastoralism, military land use and landscape position in an Australian tropical savanna
Authors: Woinarski J. C. Z. , Ash A. J.
Published: March 2003

Despite the hegemony of pastoralism over most of Australia’s tropical savannas, its impacts upon biodiversity are poorly known. There is even less knowledge about the impacts of military training, a recent, but rapidly expanding, alternative land use. We compare impacts of these land uses upon mammals, birds, reptiles and frogs at a site in north‐eastern Australia, with sampling from 24 quadrats stratified by four landscape positions (upper slope to riparian) and three current land‐use types (pastoralism, military training and undisturbed). Prior to exclusion in 1967, the whole study area had been subjected to grazing over the course of approximately 100 years, so differences observed strictly reflect responses to changed land use (largely cessation from grazing) over the period of 32 years subsequent to the imposition of the present regime. The four classes of vertebrates showed contrasting responses. Frog distribution was unrelated to land use, but strongly associated with landscape position. Reptiles showed a very strong response to land‐use type but not to landscape position. The total abundance and richness of reptiles was greater in ungrazed (i.e. military and undisturbed) than in grazed quadrats. The total abundance and species richness of birds varied strongly with landscape position but was unrelated to land use. However, many individual bird species showed significant responses to land‐use type, and bird species composition was significantly related to both land‐use type and landscape position. The richness of the mammal fauna was weakly related to landscape position and not related to land‐use type. A few individual mammal species showed significant responses to either or both factors, but mammal species composition was significantly (albeit weakly) related only to land‐use type. With due regard to some interpretative constraints in the study design, and the history of the site prior to this study, these results suggest that pastoralism leads to a substantial rearrangement of the vertebrate fauna, and particularly so for reptiles and those mammals and birds associated with the ground and understorey layers. Given the extent of pastoralism across the tropical savannas, these results suggest that this industry has contributed to major and widespread change in the savanna fauna. In contrast to pastoralism, military land use (at least at the relatively low intensity examined here) produced little change in vertebrate assemblages.
Response of ant and terrestrial spider assemblages to pastoral and military land use, and to landscape position, in a tropical savanna woodland in northern Australia
Authors: Woinarski John C. Z. , Andersen Alan N. , Churchill Tracey B. , Ash Andrew J.
Published: March 2003

This study aims primarily to assess the response of two invertebrate groups to the effects of pastoralism and military training, at one site in the tropical savanna of north‐eastern Queensland. The richness and species composition of ants and terrestrial spiders were examined at two contrasting times of year across three land use treatments (pastoralism, military training and undisturbed) and four landscape positions (upper slope to riparian). Ant species richness was least in the grazed sites, and a high proportion of the ant species recorded varied significantly in frequency between the grazed and the two ungrazed land uses. This variation was generally greater than that associated with landscape position. Although variation in the richness of spiders was significantly related to land‐use type, this effect was less pronounced than for ants, was less marked than variation associated with landscape position and was confounded by a strong interaction between land use and landscape position. Quadrat‐scale variation in the composition of spider assemblages was influenced most by season of sampling. For both spiders and ants, there were few differences in richness or species composition between undisturbed land and that managed for military use.
Interspecific competitive ability of homokaryotic and heterokaryotic wood decay basidiomycetes
Authors: Fryar S. C. , Kirby G. C. , Hyde K. D.
Published: March 2003

The role of the homokaryotic life stage in the dynamics of fungal communities is relatively unknown. However, homokaryons are thought to be only a temporary stage and are therefore not generally used in ecological experiments with fungi. In this study, the relative competitive ability and growth rates of homokaryons and heterokaryons of wood decay fungi were tested to assess the potential role of homokaryons in community dynamics. A homokaryon and a heterokaryon of each of four species (Aleurodiscus lividocoeruleus, Peniophora sp. 1, Peniophora sp. 2 and Pereniporia medulla‐panis) were assessed for their competitive abilities on an agar medium. The relationship between nuclear status and competitive ability varied between species. The homokaryon of Peniophora sp. 2 was competitively superior to its heterokaryon, whereas the homokaryon of Peniophora sp. 1 was inferior to its heterokaryon. A hierarchy of competitive abilities of each isolate revealed that Pereniporia medulla‐panis homokaryon = P. medulla‐panis heterokaryon > Peniophora sp. 1 heterokaryon > Peniophora sp. 2 homokaryon > Peniophora sp. 2 heterokaryon > A. lividocoeruleus heterokaryon = A. lividocoeruleus homokaryon. This experiment indicates that homokaryons as well as heterokaryons have the potential to influence community structure through competitive effects.