bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ecological impacts of dams, water diversions and river management on floodplain wetlands in Australia
Authors: Kingsford R.T. 
Published: March 2003

AbstractAustralian 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

AbstractThe 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

AbstractThe 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

AbstractFine‐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

AbstractThis 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

AbstractThe 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

AbstractI 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

AbstractClimbing 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

AbstractSuccessful 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

Abstract 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

AbstractThe 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

AbstractTheoretical 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

AbstractThe 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

AbstractThe 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

AbstractThe 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

AbstractReproductive 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.