bluuebunny/crossref_metadata_2025 huggingface dataset:
Response of an open‐forest ant community to invasion by the introduced ant, Pheidole megacephala
Authors: Vanderwoude C. , Lobry De Bruyn L. A. , House A. P. N.
Published: March 2003

The introduced tramp ant, Pheidole megacephala, is a well‐known pest of urban areas and coastal dune ecosystems in eastern Australia. Until recently, establishment and spread of P. megacephala colonies has been regarded as likely only in disturbed areas. Here we describe the extent of an established colony of P. megacephala in a long undisturbed open forest near Maryborough in southeast Queensland and compare ant community structure with those of nearby uninfested sites. Tuna baiting revealed three distinct zones: (i) a zone totally dominated by P. megacephala (at least 10 ha) where few other ant ant species were detected; (ii) a zone where P. megacephala was absent and many other ant species were found; and (iii) a zone where opportunists (species of Ochetellus and Paratrechina) competed with P. megacephala at baits. Pitfall trapping over a 9‐month period resulted in 12 species being recorded at the infested site, compared with a mean of 25 species recorded at adjoining uninfested forest. Over 94% of ants recorded in pitfalls at the infested site were P. megacephala. Most notably, P. megacephala had completely displaced dominant Dolichoderines (species of Iridomyrmex), subordinate Camponotini (species of Camponotus, Opisthopsis and Polyrhachis) and other species of Pheidole which are common at forest sites.
Conservation biology of the succulent shrub,Euphorbia barnardii, a serpentine endemic of the Northern Province, South Africa
Authors: Knowles Laura , Witkowski E. T. F.
Published: March 2003

Euphorbia barnardiiWhite, Dyer & Sloane is a relatively small, succulent shrub found in the Northern Province of South Africa. In 1994 it was listed as endangered by the Transvaal Threatened Plants Programme, because only three populations, totalling 1150 plants, were found. However, our study found five populations totalling 10 783 plants (9503 were reproductive). One population, found 50 km from the others, in the Bewaarkloof district, differs in terms of habitat type and morphology and may therefore be a different taxon. The other populations occur in Sekhukhuneland. Soil analyses showed thatE. barnardiiis restricted to ultramafic (serpentine) substrates. A sample of 2015 plants was examined in 1995 for size, stage, new growth, dead branches, reproduction (indices of vigour), damage and disease. Analysis of the results of 10 years’ demographic monitoring (1985–1995) on two of the Sekhukhuneland populations showed that one population, which was vigorous in 1995, showed little change in population size and structure, while the other, which had low vigour in 1995, showed a precipitous decline to local extinction in the monitoring plot. Aerial photographs taken in 1957 (1963 for Bewaarkloof) and 1986 showed large increases in human population density within 1.5 km of theE. barnardiipopulations except at Bewaarkloof, where it decreased. An increase in human habitation is associated with an increase in livestock (mostly cattle and goats) which trample plants. Trampling damages the terminal segments, which may lead to lowered reproductive output and increase susceptibility to opportunistic bacterial wilt pathogens. Bacterial wilts were prevalent on all populations but were particularly high at Bewaarkloof and on the population that showed a steep decline in numbers. Disease incidence was associated with the level of plant damage. The impact on plants further up the slopes and on the crest of hills (quite far from human settlements) was to a far lesser degree but further increases in human population density could change this situation. While this study has shown that the population size ofE. barnardiiis much greater than previously thought, the species is still threatened by several different processes and should be listed as ‘Vulnerable (A1a + c, B1, B2b + e, C1, D2)’ according to World Conservation Union categories.
Dynamics of cryptogamic soil crusts in a derived grassland in south‐eastern Australia
Authors: Eldridge D. J. , Semple W. S. , Koen T. B.
Published: March 2003

We examined the dynamics of cryptogamic soil crusts in a derived (disclimax) grassland near Orange in south‐eastern Australia. Changes in the cover of cryptogamic crusts and floristics and abundance of the constituent species were measured on four treatments with two levels each of grazing and cultivation. Twenty‐two lichens, mosses and liverworts were found at the study site and, of these, 13 were collected in the quadrats. Three moss species (Barbula calycina, Eccremidium arcuatum and Bryum pachytheca) and one lichen species (Cladonia tessalata) accounted for 67% of total cover‐abundance scores. Generally, cover‐abundance was significantly higher in the unvegetated microsites than in the vegetated microsites. Species richness was not significantly different between the four grazing‐cultivation treatments but, on average, there were significantly more species in the unvegetated microsites (mean = 3.2 species) than in the vegetated microsites (0.54 species). Grazing and cultivation resulted in significantly greater cover of bare ground and consequently significantly greater crust cover. Averaged across all treatments, approximately half of the area of unvegetated soil was occupied by cryptogams. Overall, the results indicate that lichens and bryophytes are important components of derived temperate grasslands, surviving in even densely vegetated swards. This study suggests that strategies which disturb the soil surface (e.g. grazing and cultivation) will stimulate the abundance and cover of soil crust organisms by increasing the availability of unvegetated microsites.
Dormancy and germination characteristics of herbaceous species in the seasonally dry tropics of northern Australia
Authors: McIvor JohN. G. , Howden S. Mark
Published: March 2003

This study investigated changes in dormancy and germination over 8 months for 23 common species (annual and perennial grasses, legumes and other dicotyledons) from herbaceous communities in northern Australia. Seeds were exposed to three storage treatments: relatively constant laboratory conditions, an oven with fluctuating temperatures similar to those found on the soil surface (25/60°C), or exposed on the soil surface at Townsville. There were wide ranges of initial levels of dormancy (9–100%), rates of change of dormancy and response to the different storage conditions showing that species with several types of dormancy characteristics are able to coexist in these communities. The general trend in dormancy levels was a decline with time with the rate of decline greatest for seeds exposed on the soil surface and least for those stored in the laboratory. The species were divided into groups based on dormancy levels in seeds on the soil surface during the late dry and mid wet seasons. The dormancy characteristics of the groups were related to the ecology of the species in the groups. There was an approximately linear increase in germination rate (i.e. a decrease in the number of days to 50% of final germination) over time for all storage treatments; rates for seeds on the soil surface increased more rapidly than those of seeds in laboratory and oven samples.
Plant size and season of burn affect flowering and fruiting of the grasstree Xanthorrhoea preissii
Authors: Lamont Byron B. , Swanborough Perry W. , Ward David
Published: March 2003

Flowering and fruiting were assessed on 14 populations of the grasstree, Xanthorrhoea preissii Endl., occurring in the Darling Range near Perth, Western Australia. Independent of site, season of burn or year of flowering, there was a strong relationship between plant height, which varied from 0.1 to over 2 m, and the incidence of postfire flowering, which varied from 1% (winter burn) to 75% (summer burn) of grasstrees present. There was no relationship between inflorescence dimensions, or flower or fruit production on a spike basis, and plant size/age (height). When standardized for height, spring‐burnt populations produced 40% as many inflorescences as autumn‐burnt populations and 20% as many as summer‐burnt populations. Inflorescences produced by spring‐burnt plants were moderately smaller than those by summer–autumn‐burnt plants. Fruit density per spike in autumn‐burnt plants was 80% of that in spring–summer‐burnt plants. The net effect was an average of 70 000 fruits produced per 100 summer‐burnt plants, 22 000 in autumn‐burnt plants, and 14 000 in spring‐burnt plants. Ecophysiological explanations of these results and their implications for population dynamics have yet to be explored.
Effect of density on spatial distribution, pit formation and pit diameter of Myrmeleon acer Walker, (Neuroptera: Myrmeleontidae): patterns and processes
Authors: Day M. D. , Zalucki M. P.
Published: March 2003

The effect of increasing population density on the formation of pits, their size and spatial distribution, and on levels of mortality was examined in the antlion Myrmeleon acer Walker. Antlions were kept at densities ranging from 0.4 to 12.8 individuals per 100 cm2. The distribution of pits was regular or uniform across all densities, but antlions constructed proportionally fewer and smaller pits as density increased. Mortality through cannibalism was very low and only occurred at densities greater than five individuals per 100 cm2. Antlions in artificially crowded situations frequently relocated their pits and when more space became available, individuals became more dispersed with time. Redistribution of this species results from active avoidance of other antlions and sand throwing associated with pit construction and maintenance, rather than any attempt to optimise prey capture per se.
Social and mating systems of the protandrous anemonefish Amphiprion perideraion under the influence of a larger congener
Authors: Hattori Akihisa
Published: March 2003

The effect of a larger anemonefish Amphiprion clarkii (Bennett) on the social and mating system of a smaller congener Amphiprion perideraion (Bleeker) was investigated on a coral reef at Okinawa, Japan, where both species use the same host sea anemone Heteractis crispa (Ehrenberg). The population of A. perideraion consisted of adult, subadult and juvenile groups. Adult groups, which consisted of one or two adults and a varying number of subadults and juveniles, usually did not share the host with A. clarkii. In contrast, subadult and juvenile groups, which included no adults, always cohabited with A. clarkii. In the heterospecific groups, subadult A. perideraion were able to mature histologically, and changed to female when they were the largest among conspecific members, although their reproduction was suppressed by A. clarkii. After all members of A. clarkii emigrated or disappeared from a heterospecific group, adult A. perideraion could begin breeding. I suggest that A. perideraion in both heterospecific and conspecific groups adopt a mating strategy that involves waiting for vacated breeding posts because of their low mobility and a low host density.
Ecological impacts of dams, water diversions and river management on floodplain wetlands in Australia
Authors: Kingsford R.T.
Published: March 2003

Australian floodplain wetlands are sites of high biodiversity that depend on flows from rivers. Dams, diversions and river management have reduced flooding to these wetlands, altering their ecology, and causing the death or poor health of aquatic biota. Four floodplain wetlands (Barmah‐Millewa Forest and Moira Marshes, Chowilla floodplain, Macquarie Marshes, Gwydir wetlands) illustrate these effects with successional changes in aquatic vegetation, reduced vegetation health, declining numbers of water‐birds and nesting, and declining native fish and invertebrate populations. These effects are likely to be widespread as Australia has at least 446 large dams (>10 m crest height) storing 8.8 × 107 ML (106 L) of water, much of which is diverted upstream of floodplain wetlands. More than 50% of floodplain wetlands on developed rivers may no longer flood. Of all of the river basins in Australia, the Murray‐Darling Basin is most affected with dams which can store 103% of annual runoff and 87% of divertible water extracted (1983–84 data). Some floodplain wetlands are now permanent storages. This has changed their biota from one tolerant of a variable flooding regime, to one that withstands permanent flooding. Plans exist to build dams to divert water from many rivers, mainly for irrigation. These plans seldom adequately model subsequent ecological and hydrological impacts to floodplain wetlands. To avoid further loss of wetlands, an improved understanding of the interaction between river flows and floodplain ecology, and investigations into ecological impacts of management practices, is essential.
Chick‐provisioning behaviour of two shearwaters breeding in south‐eastern Australia
Authors: Schultz M. A. , Klomp N. I.
Published: March 2003

The chick‐provisioning behaviour of the short‐tailed shearwater Puffinus tenuirostris and the wedge‐tailed shearwater Puffinus pacificus was investigated in a mixed colony on Montague Island, New South Wales, Australia, over two breeding seasons. This colony is located at opposite edges of the breeding distribution of the two species. Frequent weighing techniques were used to determine chick feeding frequency, feed timing, meal size, chick weight loss and indices of food conversion efficiency of the chicks. Short‐tailed shearwater parents fed their chicks larger more infrequent meals than wedge‐tailed shearwater parents. Short‐tailed shearwater chicks demonstrated higher food conversion efficiencies and lower weight loss than wedge‐tailed shearwater chicks, indicating either differences in diet or metabolic rates. The feeding frequency in wedge‐tailed shearwaters also fluctuated more widely than for short‐tailed shearwaters over the two breeding seasons. Despite the fact that the timing of the breeding cycle on Montague Island is almost identical for the two species, these differences in chick provisioning are probably a result of differences in prey type and location, so they may help explain variations in annual breeding success and limits to the distribution of the two species.
Bet‐hedging and germination in the Australian arid zone shrub Acacia ligulata
Authors: Letnic Mike , M Christopher R. Dickman and Gayle
Published: March 2003

The diaspore of the Australian arid zone shrub Acacia ligulata is dispersed by birds and ants. To investigate the benefits of providing a dispersal structure attractive to both groups, we compared the germination response and viability of seeds eaten by birds, handled by ants or collected from trees to simulated precursors of germination: scarification, fire and rainfall were simulated. Seed germination and viability were related to the degree of preheating disturbance to the seed coat. Heating increased the germinability of seeds not scarified or eaten by birds. In the absence of heating, ingestion by birds increased germinability. Heating increased the mortality of seeds. Our results suggest that ingestion of seeds by birds may break seed dormancy and hence enable some seeds to germinate soon after dispersal. Alternatively, seeds not eaten by birds are likely to remain dormant until sufficiently scarified by soil or stimulated by fire. Consequently, in areas such as the Simpson Desert, A. ligulata may be able to use a range of seedling establishment ‘windows’ provided by monsoon rains, post‐fire environments and unseasonal winter rains, and also spread the risk of unsuccessful seedling establishment by retaining dormant seeds in the seedbank.
Corticolous bryophytes in microphyll fern forests of south‐east Queensland: distribution on Antarctic beech (Nothofagus moorei)
Authors: Franks A. J. , Bergstrom D. M.
Published: March 2003

Fine‐scale variation in corticolous bryophyte communities was examined on the lower trunk of Antarctic beech (Nothofagus moorei) trees within microphyll fern forests of south‐east Queensland. Analysis of the variation revealed that the composition and structure of the community altered with both the height above ground level and the direction of exposure. Patterns of distribution were thought to primarily reflect changes in the moisture availability on and around the basal trunk ofNothofagus mooreitrees and the degree of desiccation tolerance exhibited by the various taxa.
Use of habitat by the black rat (Rattus rattus) at North Head, New South Wales: an observational and experimental study
Authors: Cox Michelle P. G. , Cox Chris R. Dickman and Warren G.
Published: March 2003

This study investigated the habitats used by an introduced species of rodent, the black rat Rattus rattus (Linnaeus), at North Head in New South Wales, Australia. At a coarse scale, combined live‐trapping and radio‐tracking indicated that animals used forest proportionately more than open, heath or scrub macrohabitats that were available. To identify the components contributing to this pattern, microhabitat use was assessed by scoring vegetative and structural features around trap stations, and by using spool‐and‐line tracking. The results indicated that rats preferred microhabitats providing a deep cover of leaf litter and dense understorey with numerous vertical stems. As statistical analysis did not distinguish which of these components was more important in determining habitat use, we designed an experiment to test the importance of a single component: leaf litter. Cover of litter was enhanced experimentally at 75 trap stations and reduced at 75 others, and the response of rats monitored by live‐trapping on two occasions. Although no clear response was found in the first run of the experiment, due to low numbers, rats strongly selected trap stations with enhanced leaf litter in the second run. These results indicate that litter cover affects use of habitat by the black rat. Access to food resources and avoidance of predators may contribute to the observed local patterns of abundance.
Isotopic assessment of the hydrologic importance of fog deposition on tall snow tussock grass on southern New Zealand uplands
Authors: Ingraham Neil L. , Mark Alan F.
Published: March 2003

The stable isotopic composition of rain, fog and groundwater was determined for three sites on the Otago upland snow tussocklands, southeastern South Island, New Zealand, for the snow‐free period of November to June in 1996–1998. The rain and fog were collected concurrently, but the rain was consistently isotopically more depleted than the fog. The compositions of the rain form a line of the equation δD = 8.31δ18O + 13.6, which is similar to the line of δD = 8.11δ18O + 13.6 formed by the fog. The groundwater has compositions usually between those of the fog and rain, shows no isotopic evidence of evaporation, and is assumed to be a mixture of the two in sub‐equal proportions. This pattern has been observed previously only in forested regions where the tree crowns act as collection mechanisms for fog water. On the Otago uplands, the only fog collection mechanism is interception gains through fog deposition on the relatively short (0.8–1.2 m) fine wispy foliage of the native tall snow tussock grasses (Chionochloa spp.). These results support earlier but debated claims that interception of fog by the foliage of the dominant tall snow tussock grasses makes a substantial contribution to the water yield from these uplands.
Dynamics of an age‐structured population drawn from a random numbers table
Authors: Murray Bertram G.
Published: March 2003

I constructed age‐structured populations by drawing numbers from a random numbers table, the constraints being that within a cohort each number be smaller than the preceding number (indicating that some individuals died between one year and the next) and that the first two‐digit number following 00 or 01 ending one cohort’s life be the number born into the next cohort. Populations constructed in this way showed prolonged existence with total population numbers fluctuating about a mean size and with long‐term growth rate (r) ≈ 0. The populations’ birth rates and growth rates and the females’ per capita fecundity decreased significantly with population size, whereas the death rates showed no significant relationship to population size. These results indicate that age‐structured populations can persist for long periods of time with long‐term growth rates of zero in the absence of negative‐feedback loops between a population’s present or prior density and its birth rate, growth rate, and fecundity, contrary to the assumption of density‐dependent regulation hypotheses. Thus, a long‐term growth rate of zero found in natural populations need not indicate that a population’s numbers are regulated by density‐dependent factors.
Climbing asparagus, Asparagus scandens Thunb.: a South African in your forest patch
Authors: Timmins Susan M. , Reid Virginia
Published: March 2003

Climbing asparagus, Asparagus scandens Thunb., currently has a patchy distribution in New Zealand, mainly in disturbed lowland forest remnants near towns and the coast, predominantly in the North Island but found as far south as Banks Peninsula. Here it prevents regeneration of native seedlings and smothers or strangles understorey shrubs and saplings. Based on its current distribution, it tolerates open sunny sites to deep shade and damp or dry forest. Left unchecked and aided by birds and humans, climbing asparagus is likely to spread considerably in the next decade, consolidating its current distribution in New Zealand. Several characteristics of the species make it difficult to control: the small, fine seedlings are hard to find, adult plants entwine with native plants, much of the plant’s biomass is underground and the apical meristem will resprout if left in the ground after control.
Invasive plants: approaches and predictions
Authors: Rejmánek Marcel
Published: March 2003

Successful management of invasive weeds will require active attempts to prevent new introductions, vigilant detection of nascent populations and persistent efforts to eradicate the worst invaders. To achieve these objectives, invasion ecology offers five groups of complementary approaches. (i) Stochastic approaches allow probabilistic predictions about potential invaders based on initial population size, residence time and number of introduction attempts. (ii) Empirical taxon‐specific approaches are based on previously documented invasions of particular taxa. (iii) Evaluations of the biological characters of non‐invasive taxa and successful invaders give rise either to general or to habitat‐specific screening procedures. (iv) Evaluation of environmental compatibility helps to predict whether a particular plant taxon can invade specific habitats. (v) Experimental approaches attempt to tease apart intrinsic and extrinsic factors underlying invasion success. An emerging theory of plant invasiveness based on biological characters has resulted in several rather robust predictions which are presented in this paper.
Ecological characteristics of Brachychiton populneus (Sterculiaceae) (kurrajong) in relation to the invasion of urban bushland in south‐western Australia
Authors: Buist Marcelle , Yates Colin J. , Ladd Philip G.
Published: March 2003

Brachychiton populneus (Sterculiaceae) (Schott et Endl.) R. Br. (kurrajong) is a small tree that occurs naturally ranging from southern Queensland to Victoria. It has been widely planted as an ornamental tree in south‐western Australia. In Kings Park, B. populneus has moved from cultivation to become a weed in the adjoining bushland reserve. The aim of this study was to examine the ecology of B. populneus and the Kings Park environment in order to identify the particular conjunction of characteristics that have led to the species becoming a weed. The highest density of kurrajongs (69.3 trees ha–1) was observed in the most disturbed area of Kings Park, and there was a strong relationship between density of B. populneus and disturbance (P = 0.058). The most striking feature of the invasion was the tendency of B. populneus to occur beneath other tree species, and this was attributed to birds feeding on transported fruit in trees and rats building seed caches at their base. Mature trees produced large amounts of viable seed, but rates of seed predation were high. Weevils, beetle larvae and omnivorous vertebrates such as Australian ravens, magpies and introduced black rats were observed eating seeds. The foraging behaviour of the vertebrates may facilitate the dispersal of seeds for relatively long distances away from parent plants. Seeds that escape predation form a transient seed bank and germinate with the onset of the winter rains. Early in their development, seedlings allocate resources to form a large tap‐rooted tuber that has substantial starch and water reserves, allowing seedlings to survive the long dry and hot summers in Perth. The study observed that B. populneus could survive at least one fire by resprouting from basal dormant buds. Brachychiton populneus appears to have become a weed in Kings Park because, first, it is dispersed widely into new sites through the foraging behaviour of vertebrates and once germinated has no grazing pressure, and, second, its development of a root tuber and ability to resprout means the seedlings are resilient in this frequently disturbed Mediterranean environment. While management of existing plants is relatively straightforward, continued vigilance will be required to avoid reinvasion.
Litterfall from trees in semiarid woodlands of north‐east Queensland
Authors: McIvor John G.
Published: March 2003

The amount and chemical composition (nitrogen, phosphorus and sulfur concentrations) of the components of tree litter were measured in eucalypt woodlands at two sites (Cardigan and Hillgrove) near Charters Towers, Queensland, Australia. Annual litterfall averaged 720 kg ha–1 (Cardigan) and 1270 kg ha–1 (Hillgrove) over 3 years with leaves the major component at both sites. Rate of litterfall was greatest during September–December and lowest during May–July. Nutrient concentrations varied widely but no seasonal patterns were detected. Phosphorus concentrations in the leaf litter at Hillgrove (mean = 0.112%) were much higher than in other studies of eucalypt litter, probably reflecting the high soil phosphorus levels at the study site. Tree litter represents an important proportion of the organic material and nutrients being cycled through these woodlands.
Utilization of food resources by small and medium‐sized mammals in the Monte Desert biome, Argentina
Authors: Campos C. , Ojeda R. , Monge S. , Dacar M.
Published: March 2003

Theoretical models of species coexistence between desert mammals have generally been based on a combination of food and microhabitat selection by granivorous rodents. Although these models are applicable in various deserts of the world, they cannot explain resource use by mammals in Neotropical deserts. The present study examines diet composition in a mammal assemblage in the Monte desert, Argentina. The results show that two main strategies are used by these mammals: medium‐sized species (hystricognath rodents: Dolichotis patagonum, Lagostomus maximus, Microcavia australis and Galea musteloides; and an exotic lagomorph: Lepus europaeus) are herbivores, whereas small‐sized species (a marsupial: Thylamys pusillus; and sigmodontine rodents: Graomys griseoflavus, Akodon molinae, Calomys musculinus, Eligmodontia typus) are omnivorous. Small mammals also show a tendency towards granivory (C. musculinus), insectivory (A. molinae and T. pusillus) and folivory (G. griseoflavus).
Host plant response and phenotypic plasticity of a galling weevil (Collabismus clitellae: Curculionidae)
Authors: De Souza Andréa L. T. , Tanaka Marcel O. , Fernandes G. Wilson , Figueira José E. C.
Published: March 2003

The response of a host plant to gall‐inducing insects varies both among and within plants, so that different levels of resources are available to the insects. The weevil Collabismus clitellae Boheman induces galls on the shoots of Solanum lycocarpum St Hil. in south‐east Brazil. Galls are found on a range of parts within an individual plant and are more abundant on smaller plants. In the present study, the host plant response as a possible influence on the performance of C. clitellae both between and within plants was tested. Gall abortion increased with plant height. Within plants, gall size was positively related to shoot diameter and number of chambers within the gall. The increase in gall larval density (number of individuals per gall volume unit) resulted in smaller adults and reduced developmental rates, probably because of resource limitation within the gall. The number of eggs laid by females increased with shoot diameter. Females laid more eggs on thicker shoots, where there are fewer chances to form galls with high larval density. However, this relationship was weak and a large variation was found for adult sizes. The availability of high quality sites is limited to smaller plants and thicker shoots located on the basal region of the plant. The phenotypic plasticity of this insect species in adult size and development time allows individuals growing on low quality sites to reach maturity, thus enhancing exploitation of the host plant.
Edaphic patchiness influences grassland regeneration from the soil seed‐bank in mountain grasslands of central Argentina
Authors: Funes Guillermo , Basconcelo Sandra , Díaz Sandra , Cabido Marcelo
Published: March 2003

The soil seed‐banks in the main natural vegetation patches that make up mountain grasslands on granite substrates in central Argentina were studied. The main natural vegetation types are moist swards, tall‐tussock grasslands and stony grasslands. Ten compound soil samples from each community at two soil depths (0–5 and 5–10 cm) were taken. The density of soil seed‐banks was highest in moist swards, intermediate in stony grasslands and lowest in tall‐tussock grasslands. Low levels of similarity were found between the established vegetation and total soil seed‐bank in tall‐tussock grasslands and stony grasslands, but the similarity was higher in swards. In all three communities the seed‐bank was most frequently transient in nature. Short‐term persistent and long‐term persistent seed‐banks were less frequent. Regeneration from the seed‐banks after disturbance is expected to differ among communities on different edaphic patches. On the basis of the density and longevity of the soil seed‐banks and the similarity to the established vegetation, potential for in situ regeneration should be lower in tall‐tussock grasslands, intermediate in stony grasslands and higher in moist swards.
Effects of elevated CO2 on the foliar chemistry of seedlings of two rainforest trees from north‐east Australia: Implications for folivorous marsupials
Authors: Kanowski John
Published: March 2003

The present study examined the effects of elevated levels of atmospheric CO2 on foliar concentrations of nitrogen, mineral nutrients and phenolics, and leaf toughness, in seedlings of two common rainforest trees from north‐east Queensland, Australia. The trees were the pioneer species Alphitonia petriei Braid and C. White and the mid‐successional species Flindersia brayleyana F. Muell. Both species are important in the diets of folivorous marsupials endemic to the region. Seedlings were grown in native rainforest soils (nutrient‐rich basalt and nutrient‐poor rhyolite) and exposed to unreplicated treatments of ambient (350 p.p.m.) and elevated (790 p.p.m.) CO2 for 60 days in a glasshouse. The foliage of seedlings exposed to elevated CO2 had lower concentrations of nitrogen and sodium than did seedlings exposed to ambient conditions. Nitrogen levels declined by 4.5 mg g‐1 in Alphitonia and 5.9 mg/g in Flindersia, or 25 and 29% of ambient levels, respectively. Sodium levels declined by 44% in both species. In Flindersia, concentrations of phosphorus, potassium and calcium were also reduced in elevated CO2 by 19–28% of ambient levels, but these minerals did not vary with CO2 treatment in Alphitonia. In elevated CO2, levels of condensed tannins were higher in Flindersia, but not Alphitonia. Levels of total phenolics did not vary significantly with CO2 in Flindersia; whereas in Alphitonia, total phenolics were lower in elevated CO2, but only on basalt soils. Leaves were thicker in both species in elevated CO2. Leaves were tougher in both species in elevated CO2, but only on rhyolite soils. If the results of the present study can be extrapolated to mature trees exposed to elevated CO2 over the long‐term, folivores would be expected to become less abundant under elevated CO2 conditions, as foliar chemistry is a good predictor of folivore abundance in the higher elevation rainforests of north‐east Queensland.
Potential ‘costs of reproduction’ in a skink: Inter‐ and intrapopulational variation
Authors: Wapstra Erik , O'Reilly Julianne M.
Published: March 2003

Reproductive costs are important determinants of reproductive effort in squamate reptiles. Consequently, differences in costs of reproduction between populations of geographically or climatically widespread species are likely to result in different patterns of reproductive effort. In the present study, the effect of pregnancy on sprint speed was examined in a small viviparous skink,Niveoscincus ocellatus(Gray 1845), from two populations at the climatic extremes of its distribution. Decreased sprint speed has the potential to be an important cost of reproduction in this species, through a reduced ability to avoid predation and/or decreased foraging efficiency. Lizards inhabiting the colder site were larger than those from the warmer site and, contrary to predictions from life history theory, had a higher reproductive effort. In both populations, sprint speed was lower in pregnant lizards than in either the same individuals after birth or non‐pregnant control lizards. Within each population, sprint speed was unrelated to the level of reproductive effort of the female in terms of either absolute mass of the reproductive burden or the burden relative to her post‐partum body mass. However, within each population, the mass of the clutch that an individual female was carrying relative to snout–vent length was an important determinant of her sprint speed while pregnant. Thus, within each population, a relatively high reproductive burden may potentially increase costs of reproduction in this species. Despite this relationship and predictions from life history theory suggesting that annual reproductive effort will be lower in populations with a large body size and delayed maturity, it is suggested that a higher reproductive effort at the cold site is possible because they have a higher absolute sprint speed because of their larger size and a relatively higher abundance of cover at the cold site, and differences in predation pressure may alter selective pressures on reproductive investment.
Grasshopper biodiversity and bioindicators in Australian tropical savannas: Responses to disturbance in Kakadu National Park
Authors: Andersen Alan N. , Ludwig J. A. , Lowe Lyn M. , Rentz D. C. F.
Published: March 2003

Grasshoppers are a dominant group of herbivorous insects throughout the world, and their high diversity, functional importance, sensitivity to disturbance and ease of sampling makes them potentially useful bioindicators for land management. In Australia, however, the dynamics of grasshopper assemblages are extremely poorly understood. Here we describe the responses of grasshopper (Acridoidea, Eumastacoidea and Tettigonioidea) assemblages in the Kakadu region of the Northern Territory, Australia to disturbance associated with mining. Three questions were addressed in this study: (i) do local grasshopper assemblages show consistent responses to disturbance?; (ii) can particular species or functional groups be identified that are reliable indicators of ecological disturbance?; and (iii) to what extent do the responses of grasshopper assemblages merely reflect those of vegetation? Grasshoppers were sampled at 26 sites located in and around the Ranger uranium mine, representing three habitat types with respect to degree of disturbance: (i) ‘natural’ (10 sites representing a range of ‘undisturbed’ savanna habitats); (ii) ‘disturbed’ (10 sites representing a range of disturbances, but with soil intact); and (iii) ‘waste rock’ (six sites undergoing rehabilitation on a constructed landform). A total of 56 grasshopper species in 46 genera was recorded during the study, with site species richness ranging from five to 20. There were no significant differences between habitat types in site species diversity, but multivariate analysis demonstrated a strong correspondence between grasshopper species composition and degree of habitat disturbance. Using Indicator Species Analysis, six species and one functional group were identified as significant indicators of habitat type in relation to disturbance. Grasshopper responses were correlated with that of vegetation, but grasshopper assemblages showed apparently meaningful differentiation among disturbed sites that was not evident on the basis of floristic data. Our results demonstrate that grasshopper assemblages respond to disturbances associated with human land use and that these responses do not simply reflect those of plants. Grasshoppers are therefore potentially useful bioindicators of ecological disturbance in Australia, but further work is required on the extent to which their responses reflect general ecological change.
Mate selection in Litoria chloris and Litoria xanthomera: Females prefer smaller males
Authors: Morrison Clare , Hero Jean‐Marc , Smith William P.
Published: March 2003

It is generally accepted that high quality males are those that succeed in male–male competition: in either aggression or rivalry to attract and be selected by females. Previous studies of amphibians have suggested that the main characters influencing male mating success include variation in call characteristics (e.g. call rate, call intensity), calling behaviour, body condition, age and chorus tenure. In the present paper, several of the characters influencing female mate choice (male body size, body condition, call rate, call frequency and chorus tenure) are investigated in two closely related, explosive breeding frog species Litoria chloris and Litoria xanthomera. Smaller males of both species are shown to be more successful than larger males and this success is attributed to the increased chorus tenure of smaller males in L. xanthomera. This increased chorus tenure was attributed to the lower total energy used per call by a small male calling at a higher frequency. Whether increased chorus tenure explains female mate choice in L. chloris is uncertain but is highly probable given the strong similarity between the two species in both ecology and call characteristics.
Opinion Practical and ethical considerations for students conducting ecological research involving wildlife
Authors: Monamy Vaughan , Gott Miranda
Published: March 2003

This commentary outlines relevant changes to the Australian Code of Practice for the Care and Use of Animals for Scientific Purposes for ecologists and students active in field‐based wildlife research. All field‐based activities that require the approval of an Animal Ethics Committee (AEC) have now been detailed within the revised Code of Practice. Researchers and their students are required to give explicit consideration to the humane principles of replacement, reduction and refinement within their experimental protocols as a part of the AEC permission procedure. University‐based researchers also have obligations to train graduate students in the ethical as well as the practical components of wildlife research. In promoting this educational aim, a summary of ethical considerations in wildlife research is offered as a basis for discussion: the regulatory framework of research animal welfare (including an introduction to the Code of Practice, the AEC process and some thoughts on experimental design); and the humane principles on which the Code of Practice is based. Some practical considerations for field work relevant to students’ research training are also described.
Seed hoarding by rodents of the Monte Desert, Argentina
Authors: Giannoni Stella M. , Dacar Mariana , Taraborelli Paula , Borghi Carlos E.
Published: March 2003

Food storage is an important adaptation of several animal species to the temporally variable or unpredictable food supplies that are typical of desert environments. In the present study, whether Eligmodontia typus and Graomys griseoflavus inhabiting sand dunes in the Monte desert displayed scatter‐hoarding was investigated. Both rodent species prepared surface caches by digging small holes (1–3 cm deep) in the soil. Caches were partially covered with sand and dry leaves, which meant that all of the cache sites at each station could be found. Most caches were found below shrubs, that is, in a sheltered microhabitat rather than near the food source. The mean distance between caches and seed sources was significantly higher than the mean distance from food sources to shrubs. The proportion of caches was significantly higher in shrubs with high safety cover. The adaptive significance of this foraging behaviour could be a competitive tactic for the rapid sequestering of food from a rich and ephemeral source. Such behaviour would reflect predation risk, which constitutes an important foraging cost in deserts, and could also influence plant community dynamics.
Changes in wolf spider (Araneae) assemblages across woodland–pasture boundaries in the central wheat‐belt of New South Wales, Australia
Authors: Martin Timothy J. , Major Richard E.
Published: March 2003

The abundance of wolf spiders (Lycosidae) was measured across woodland–pasture boundaries in the wheat‐belt of New South Wales, Australia, to determine the nature and magnitude of any edge effect. Spiders were collected by spotlighting along sample plots in woodlands located at distances of 5, 20, 35 and 200 m from the edge, and along sample plots in paddocks located at distances of 5 and 20 m from the edge. The wolf spider assemblage changed significantly across the edge, but the difference could be accounted for only by a change between the woodland and the paddock and not by any changes within the woodland at different distances from the edge. Ground cover (wolf spider microhabitat) changed significantly between the paddock and the woodland, but there were no consistent differences in microhabitat with distance from edge within either paddocks or woodlands. There was a significant correlation between an ordination of sites based on spider species abundance and an ordination based on microhabitat variables, suggesting that the wolf spider assemblage was responding to differences in microhabitat. Fine‐scale selection of microhabitat by most wolf spider species was non‐random, with most species preferring locations with grass cover, rather than more open locations. The present study indicates that wolf spiders are mostly unaffected by edge conditions at the woodland–paddock boundary. Accordingly, small and/or linear remnants with high edge‐to‐area ratios may constitute suitable faunal habitat for wolf spiders and perhaps other terrestrial arthropod species, despite the fact that this configuration is unsuitable for many vertebrate species.
Density, home range, seasonal movements and habitat use of the mountain pygmy‐possumBurramys parvus(Marsupialia: Burramyidae) at Mount Blue Cow, Kosciuszko National Park
Authors: Broome Linda S.
Published: March 2003

A population of mountain pygmy‐possumsBurramys parvuswas studied at the Mount Blue Cow ski resort in Kosciuszko National Park between 1986 and 1989. Forty‐eight individuals were radiotracked during the snow‐free months and 21 individuals were tracked during winter over the 3 years of study. Trapping and radiotracking showed that the density, population structure, movements and home range sizes ofB. parvuson Mount Blue Cow were strongly correlated with elevation and changed with the season. Female densities were greatest in habitats characterized by deep boulderfields, at high elevations with an abundance of Bogong moths. Males visited the areas where females were located to breed in November–December and then by February, the majority migrated to lower elevations or north and westerly aspects. Females that nested at lower elevations also visited high‐elevation habitats to access the high concentrations of Bogong moths, which were the main food source in summer. A high proportion of the juvenile males and some juvenile females dispersed to lower elevations in March and April. The resulting sexual segregation during autumn and winter may be a result of female aggression or scramble competition, but is also explainable by differences in energy requirements, seed availability and hibernation strategies between the sexes. The extraordinarily large nightly and seasonal movements between habitat patches of up to 2 km for females and 3 km for males, sexual segregation and the use of different hibernation sites have important implications for the management of this species. These include the need for movement and dispersal corridors and the conservation of boulder‐heath habitats outside the main boulderfields.
Assessing the disturbance impact on vegetation and lizard communities of fluoride pollution interacting with fire and mining in eastern Australia
Authors: Taylor Jennifer E. , Fox Barry J.
Published: March 2003

The effects of atmospheric fluoride pollution on the lizard fauna of the open forest of coastal dunes in New South Wales, Australia were examined. Lizards were pitfall‐trapped at sites with background fluoride levels (< 0.25 μmol F.g–1), or subject to low (1.85–3.4 μmol F.g–1) or high (8.00–13.2 μmol F.g–1) levels of fluoride pollution. Sites had been disturbed by fire or mineral sand‐mining 4 or 8 years prior to the study. Fluoride pollution resulted in significant changes to canopy cover, understorey vegetation density and ground cover. Where fluoride levels were low in unmined forest, there was significantly higher species richness, total lizard abundance and abundance of the most common species, Lampropholis guichenoti and Lampropholis delicata (Scincidae), compared with areas of high or background fluoride levels. Both the present and previous studies show that fluoride pollution is significantly correlated with increased abundance of the most common lizard species in sand‐mined areas, Ctenotus robustus, Ctenotus taeniolatus (Scincidae) and Amphibolurus muricatus (Agamidae). A discriminant function model of background‐fluoride mined sites was used to predict lizard abundances based on vegetation density, leaf litter density and soil hardness. The model was verified by using it to predict similarities between background‐fluoride sites and fluoride‐affected sites. The sites within each predicted group were more similar in lizard species composition than when grouping of sites was done by time since mining or fire. With this analysis, a close relationship between vegetation variables and the lizard fauna, irrespective of the type of disturbance or time since disturbance, is demonstrated. Discriminant function analysis suggested that Ctenotus would be unlikely to use unmined forest sites that had been burned within 12 months previously. Thus it seems unlikely that the original open forest of these coastal dunes would have supported populations of either C. robustus or C. taeniolatus. In conclusion, the original source of Ctenotus that colonized sand‐mined areas is more likely to have been the relatively small areas of heath vegetation in the area. Therefore, sand‐mining and atmospheric fluoride pollution result in landscape‐scale changes to the relative abundance of lizard species, with forest species becoming less common and lizard species from open areas becoming more common.