bluuebunny/crossref_metadata_2025 huggingface dataset:
Gap size and regeneration in a New Zealand dairy pasture
Authors: PANETTA F. D. , WARDLE D. A.
Published: July 2006

Abstract
Seedling emergence of three weeds (Carduus nutans, Cirsium vulgare and Rumex obtusifolius) and three clovers (Trifolium repens, T. subterraneum and T. pratense) was monitored in gaps of different sizes (0, 2, 6 and 10 cm diameter, plus a 3 m2 bare plot), which were created in a Loliumperenne/T. repens pasture. Clover emergence was greatest in the bare plots, in contrast with the weeds, whose emergence peaked in small or intermediate‐sized gaps. Relationships between weed emergence and gap size in glasshouse swards were poorly denned. As a result of trampling by cattle, seedling mortality occurred most rapidly for all species in the bare plots. Very few weeds survived in the other gaps, where there was no detectable effect of gap size upon survivorship. Naturally occurring gaps were most abundant during summer, but their size frequency distributions varied little between spring and autumn. The sizes of almost 95% of the natural gaps were within the range of the experimentally‐created gaps. Poor survivorship of weeds within this range, however, suggests that larger gaps are required for regeneration.
Germination, seedling occurrence and seedling survival of Spinifex sericeus R. Br. (Poaceae)
Authors: MAZE K. M. , Whalley R. D. B.
Published: July 2006

Abstract
Spinifex sericeus is a clonal, perennial, dioecious, coastal foredune grass that is often used in beach rehabilitation programmes. The objectives of this study were to: (i) investigate the germination behaviour of S. sericeus; and (ii) examine the occurrence and survivorship of 5. sericeus seedlings in the dune systems on the mid‐north coast of NSW. Diaspores and naked caryopses of S. sericeus require darkness for germination. Diaspore germination is adversely affected by leaching, probably due to the creation of anaerobic conditions around the caryopsis. Seedling emergence occurs mainly on the front of the foredune, as this is an area of active sand accretion and burial is necessary for germination. The presence of a hypocotyl allows germination and emergence from depths as great as 12.5 cm. In the two populations studied, seedling survival was low and probably made little contribution to population recruitment. The factors that appear to be responsible for the high mortality rate of seedlings are sand erosion, sand deposition and desiccation.
Comparing two sets of community data: A method for testing reserve adequacy
Authors: BELBIN L.
Published: July 2006

Abstract
Comparing a new set of samples to what may be considered a reference set is a common problem in ecology. The investigator may be interested in the degree of correspondence or any anomalies. For example, does a set of existing reserves adequately cover the range of communities sampled in a region? A technique for such comparisons is proposed. Being dependent solely on estimates of ecological resemblance, it is simple, efficient and robust. Significant difference is defined by means of a resemblance coefficient. A threshold value denoting significant difference can be defined either by species overlap or other attributes of the data. For presence/absence data the Czekanowski coefficient provides a suitable measure of ecological resemblance. Traditional discriminant analysis does not provide a viable alternative due to its limitations in accommodating ecological data.
Flora and vegetation of ultramafic areas in Tasmania
Authors: GIBSON N. , Brown M. J. , WILLIAMS K. , Brown A. V.
Published: July 2006

Abstract
A floristic survey of the ultramafic areas of Tasmania was undertaken. In the northern areas dry sclerophyll communities with a heath understorey were found on this substrate, while in the wetter western and southern areas this geology supported heathlands, wet scrubs, wet sclerophyll/mixed forests and rainforests. One of the most striking features of the ultramafic areas in Tasmania is the variable degree of physiognomic differentiation between adjacent ultramafic and non‐ultramafic substrates at the different sites. Physiognomic differentiation is less on non‐lateritic soil types or where accumulation of colluvial material has occurred. Only three ultramafic endemic taxa have been recorded in Tasmania. One taxon is restricted to the dry north of the State while the other two taxa are found on the west coast. The endemic taxa appear to be associated with lateritic soil development. The two ultramafic endemics of the west coast are unreserved at present.
The invasive potential of Australian banksias in South African fynbos: A comparison of the reproductive potential ofBanksia ericifoliaandLeucadendron laureolum
Authors: HONIG M. A. , Cowling R. M. , RICHARDSON D. M.
Published: July 2006

AbstractSeveral taxa of the Australian Proteaceae have invaded South African fynbos and require costly management programmes to bring under control.Banksiaspp. have been introduced only recently to fynbos regions. The invasive potential ofBanksia ericifolia(Proteaceae) was investigated by comparing its recruitment potential with that of an indigenous proteaceous shrub,Leucadendron laureolum. Both species are overstorey shrubs that are killed by fire and rely on canopy‐stored seeds (serotiny) for recruitment. Eight year oldB. ericifoliashrubs produced an average of 16 500 seeds per plant, which is thirty times more than the average of 570 seeds produced by 10 year oldL. laureolumshrubs. The seed bank ofB. ericifoliawas not only larger than that ofL. laureolum(1098 vs 525 viable seeds m−2projected canopy cover), but also considerably larger than that described for the species in its native environment (200–330 seeds m−2in a 9 year old stand north of Sydney).Leucadendron laureoleumreleased most of its seed a few days after the cones were burnt, whereas seed release inB. ericifoliawas spread over 12 weeks. The seeds ofB. ericifoliahad lower wingloading and fall rates thanL. laureolumand were dispersed over greater distances. The relative seedling growth rates of the two species were very similar (0.03 g per day), but below‐ground biomass was greater and proteoid roots were more developed inB. ericifoliaseedlings than inL. laureolumafter 100 days. Four year oldB. ericifoliaplants growing in the field had attained over twice the height of indigenous pro‐teoids and accumulated up to 10 times the fresh biomass ofL. xanthoconus, a species which is ecologically similar toL. laureolum. The Bioclimatic Prediction System (BIOCLIM) was used to create a bioclimatic profile ofB. ericifoliaand identify climatically suitable areas in the Cape Province. Results show that its potential distribution covers most fynbos areas in the southwestern Cape. It is concluded thatB. ericifoliahas the potential to be highly invasive in fynbos.
Tree litter and the lower limits of subalpine herbs and grasses in the Brindabella Range, ACT
Authors: WILSON S. D. , Zammit C. A.
Published: July 2006

Abstract
Herbs and grasses form a dense understorey in subalpine woodlands dominated by Eucalyptus pauciflora but are absent from stands of Eucalyptus dives immediately down slope. We hypothesized that a relatively high rate of litter accumulation beneath E. dives was responsible for the downward limit of subalpine plants. We tested this hypothesis by removing litter and by adding E. dives litter to plots in both forest types during two growing seasons. Litter accumulation rates were 50% higher under E. dives than E. pauciflora, but understorey bio‐mass in control plots was eight times higher under E. pauciflora than E. dives. After the first growing season, seedling densities in both forest types were significantly higher in plots from which litter had been removed but, after the second growing season, understorey biomass was not higher in litter removal plots. The results indicate that litter has the potential to limit germination in both forest types, but that environmental filters other than litter subsequently limit recruitment and are ultimately responsible for the lower distributional limits of subalpine herbaceous species.
Relationship between types of prey captured and growth form in Drosera in southwestern Australia
Authors: VERBEEK N. A. M. , BOASSON R.
Published: July 2006

Abstract
Sympatrically growing species of Drosera were examined, including rosette forms, climbers and upright, self‐supporting species, in southwestern Australia, to see whether the height above ground of the capturing leaves influenced the kinds of prey caught. The leaves examined for invertebrate prey remains were all collected at the same time and the results thus represent a snapshot of the prey situation. Although the number of fully opened, active leaves and leaf size among species varied 40‐fold and 22‐fold, respectively, total catch per unit leaf area was relatively constant, regardless of growth form. Growth form was strongly correlated with the kinds of prey caught. Prostrate species caught mainly walking, non‐aerial prey, while self‐supporting and climbing species caught predominantly aerial prey.
The real story of Bridge Hill: A response to Buckney and Morrison (1992)
Authors: LEWIS JOHN W. , CLEMENTS ANNEMARIE
Published: July 2006

Abstract
In this note we demonstrate that the Buckney and Morrison (1992) data subsets are located on different geomorphological units and different pre‐mining plant communities with different fire histories. The conclusions that they have drawn from their data are therefore not valid.
Variation between Emex australis populations in seed dormancy/non‐dormancy cycles
Authors: PANETTA F. D. , RANDALL R. P.
Published: July 2006

Abstract
Seeds of four Western Australian accessions of Emex australis were stored outside and their germinability tested at 4–6 week intervals for 22 months. Accessions showed cyclical behaviour in germinability, with peaks in autumn/early winter and troughs in spring/summer. There was considerable variation between accessions in dormancy/non‐dormancy cycles, but when plants from accessions with contrasting cycles were grown in a common environment, the cycles shown by their seeds were virtually identical. Thus, the parameters of seed dormancy/non‐dormancy cycles in E. australis appear to be under environmental control.

Only part of an E. australis seed population demonstrated cyclical changes in dormancy status, in contrast to many other annual species whose entire seed populations undergo such changes. Populations also contained individuals which were either continuously dormant or continuously non‐dormant following a period of after‐ripening. The latter seeds give E. australis the flexibility to recruit opportunistically after summer rainfall events in mediterranean‐climate environments.
Population increase and nesting patterns of the black noddy Anous minutus in Pisonia forest on Heron Island: Observations in 1978, 1979 and 1992
Authors: OGDEN JOHN
Published: July 2006

Abstract
Estimates of the population size of black noddy Anous minutus on Heron Island were made by counting nests in permanently marked plots in Pisonia grandis forest in 1978, 1979 and 1992. The results, and published data, indicate that the population has been increasing at ca 7% per annum since early this century and currently is ca 63 000 ± 7000 pairs. The continued exponential increase in bird numbers poses interesting ecological questions and potential management problems, as more of the island is occupied by the birds and interaction with the vegetation intensifies. Pisonia is by far the most common tree on the island and most nests are in this species. However, there is evidence that Ficus opposita is preferred over Pisonia and the high mortality of this species in the marked plots may be due to excessive use by noddies. Pisonia trees which reach the forest canopy and are in the 40–60 cm stem diameter class have more nests than smaller trees. Larger stems (>60 cm diameter) are also underutilized relative to their size, and it is suggested that this is because they are more liable to windthrow in cyclones.
Climatic limitation of the southern distribution of the common blossom batSyconycteris australisin New South Wales
Authors: LAW BRADLEY STUART
Published: July 2006

AbstractThis study investigates the importance of climate as a factor influencing the southern distributional limit of the common blossom bat (Syconycteris australis). Using the climatic predictive model BIOCLIM and 73 locality records, 5. australis was predicted to have a coastal distribution in eastern Australia, where winter temperatures are relatively warm and moist conditions prevail throughout the year. The actual southern limit ofS. australis, determined by mist‐netting suitable habitats, was found to be at Booti‐Booti (32°19'S 152°3l'E) on the mid‐north coast of New South Wales. BIOCLIM predicted the southerly limit of 5. australis to be 150–200km further south of their actual limit. Booti‐Booti was occupied at relatively low levels of abundance year round, while the abundance ofS. australisat a site 50 km to the north was much greater, fluctuating with changes inBanksiaflower numbers. Seasonal range extensions beyond Booti‐Booti were not detected, despite the availability of apparently suitable habitat at Myall Lakes only 20–35 km further south. Metabolic costs ofS. australisat Booti‐Booti were estimated to exceed basal metabolic rate (BMR) by 4.5 times, well above the physiologically predicted limit of 2.5 times BMR. These results, together with the lack of range extensions and the close correspondence of BIOCLIM'S predicted southern limit ofS. australiswith their actual limit, suggest that the bat's southern distribution is limited by cold, wet winters and dry summers.
Biological control and the species status of two host‐associated populations of Trissolcus basalis (Wollaston) (Hymenoptera: Scelionidae).
Authors: CLARKE A. R. , WALTER G. H.
Published: July 2006

Abstract
Populations of the morphologically defined taxon Trissolcus basalis (Wollaston) from two major hosts (Nezara viridula [L.] and Agonoscelis rutila [F.]) were tested, using biological criteria, to determine whether they represented populations of one genetical species, or whether they represented populations of two host‐associated sibling species. Individuals from both hosts exhibited no obvious courtship differences and they selected mates at random in mate‐choice experiments. In addition, female wasps produced offspring of both sexes after mating with a male from either population. We conclude that the individuals of the two populations tested constitute a single genetical species.
Spatial and trophic niche differentiation in two sympatric lizards (Tropidurus torquatus and Cnemidophorus ocellifer) with different foraging tactics
Authors: BERGALLO HELENA GODOY , ROCHA CARLOS FREDERICO DUARTE
Published: July 2006

Abstract
In a ‘restinga’ habitat of southeastern Brazil, we studied the food habits and the microhabitat use of two lizards with distinct foraging modes: the tropidurid Tropidurus torquatus, a sit‐and‐wait predator, and the teiid Cnemidophorus ocellifer, a wide forager. The diet of the two species differed strongly, indicating a low level of similarity in their trophic niche. The sit‐and‐wait predator fed mainly on mobile prey, whereas the wide forager fed mainly on sedentary prey (larvae). The spatial niche breadth of T. torquatus was larger than that of C. ocellifer. Despite interspecific differences, the two species overlapped greatly in micro‐habitat use. The data indicate that at Linhares the two lizard species differed more in food resources than in microhabitat, and that most of the food differences reflect the foraging patterns of the species.
Use of algae and other plants for monitoring rivers
Authors: WHITTON BRIAN A. , KELLY MARTYN G.
Published: July 2006

Abstract
A brief account is given of the methods developed for use of algae, bryophytes and angiosperms to monitor rivers and streams. The methods fall broadly into those based on features of populations of representative species, those based on part or all of the whole photosynthetic community and those based on various types of bioassay and ecotoxicological test. The methodology for using bioaccumulation of heavy metals, insecticides and other organic molecules is well developed and has been applied widely in western Europe for practical purposes. Coarse filamentous algae and bryophytes are especially useful, but some angiosperms are suitable, provided general information about bioaccumulation in the particular species is available; it is difficult to use periphyton. Other methods based on species include measurement of genetic tolerance, physiological approaches (chlorophyll: phaeophytin ratio, tissue N: P ratio and surface phosphatase assays) and observations on cyanobacterial and eukaryotic algal morphology.

Among community‐based methods for monitoring, measurement of biomass is used widely for phytoplankton, but seems of little use for benthos. The use of indices based on benthic communities, especially diatoms, has, however, been applied widely. The earlier indices based on diversity have been replaced almost entirely by ones integrating ecological information from component species. In addition, the authors have started to produce a diatom‐based parallel to the macroinvertebrate‐based RIVPACS by obtaining floristic data from ‘clean’ sites. Bioassays and ecological tests, mainly using algae or Lemna, are often carried out together with the other methods.
The use of diatoms to assess past and present water quality
Authors: REID M. A. , TIBBY J. C. , PENNY D. , GELL P. A.
Published: July 2006

AbstractDiatoms possess a number of attributes which contribute to their suitability as biological indicators. They are highly sensitive to water chemistry changes, abundant in aquatic environments, largely cosmopolitan in distribution, less habitat dependent than macroinverte‐brates and have a well‐studied taxonomy and ecology. Furthermore, the preservation of diatom valves in lake sediments means that they can provide otherwise unavailable baseline data which can be used to assess and contextualize human impacts on aquatic ecosystems. The value of diatoms as bioindicators in contemporary and palaeolimnological studies has been well established overseas. Despite this, they have been under‐utilized in Australia. This paper outlines some of the applications and potential for the use of diatoms as biological indicators in Australia.
Rapid assessment of rivers using macroinvertebrates: Case studies in the Nepean River and Blue Mountains, NSW
Authors: CROWNS JANE E. , CHESSMAN BRUCE C. , MCEVOY PAUL K. , WRIGHT IAN A.
Published: July 2006

Abstract
Two sets of data were used to evaluate the procedure for rapid assessment of rivers described by Chessman (1995): (i) 72 samples from four habitats at 27 sites on the Nepean River and tributaries; and (ii) 41 riffle samples from the Blue Mountains. In the Nepean system all the sites had moderate anthropogenic disturbance but none had gross organic pollution. There were, however, conductivity differences related to mixed sandstone and shale lithology. The sites differed widely in natural physical attributes such as stream order (2–6) and altitude (40–600 m). The Blue Mountains data included sites with little or no anthropogenic disturbance and sites greatly affected by organic pollution. There was again a wide range of altitudes (15–1000 m) but stream orders were more restricted (1–4). The occurrence of macroinvertebrate families was analysed using cluster analysis (TWINSPAN) and ordination (semi‐strong hybrid multidimensional scaling). Relationships between the patterns observed, the SIGNAL biotic index, and physical and chemical data were investigated. The Nepean data showed that the sample size of 100 animals used in the rapid procedure was sufficient to reveal natural distribution patterns in the communities, and that SIGNAL was essentially independent of these patterns. In the Blue Mountains, water pollution had a greater effect on macroinvertebrate communities than the physical habitat, and SIGNAL distinguished sites with differing levels of pollution.
Baseline requirements for assessment of mining impact using biological monitoring
Authors: HUMPHREY C. L. , FAITH D. P. , DOSTINE P. L.
Published: July 2006

Abstract
Biological monitoring programmes for environmental protection should provide for both early detection of possible adverse effects, and assessment of the ecological significance of these effects. Monitoring techniques are required that include responses sensitive to the impact, that can be subjected to rigorous statistical analysis and for which statistical power is high. Such issues in baseline research of‘what and how to measure?’and‘for how long?’have been the focus of a programme being developed to monitor and assess effects of mining operations on the essentially pristine, freshwater ecosystems of the Alligator Rivers Region (ARR) in tropical northern Australia. Application of the BACIP (Before, After, Control, Impact, Paired differences) design, utilizing a form of temporal replication, to univariate (single species) and multivariate (community) data is described. The BACIP design incorporates data from single control and impact sites. We argue for modification of the design for particular studies conducted in streams, to incorporate additional independent control sites from adjacent catchments. Inferential power, by way of (i) more confidently attributing cause to an observed change and (ii) providing information about the ecological significance of the change, will be enhanced using a modified BACIP design. In highly valued environments such as the ARR, monitoring programmes require application of statistical tests with high power to guarantee that an impact no greater than a prescribed amount has gone undetected. A minimum number of baseline years using the BACIP approach would therefore be required in order to achieve some desired level of statistical power. We describe the results of power analyses conducted on 2–5 years (depending upon the technique) of baseline data from streams of the ARR and discuss the implications of these results for management.
Biological monitoring of water quality in Australia: Workshop summary and future directions
Authors: BUNN STUART E.
Published: July 2006

Abstract
Biological methods are widely accepted in water quality monitoring programmes worldwide; however, some concern remains over their effectiveness in predicting the effects of contaminants on aquatic ecosystems. While the so‐called‘early warning’ approaches, such as bioassays and biomarkers, have been used in Australia to demonstrate mechanisms of toxic action and exposure to contaminants, as elsewhere, little attempt has been made to link observed effects at these lower levels of biological organization to real impacts on aquatic systems. The ecological consequences of exposure to contaminants is undoubtedly best studied at higher levels of biological organization (i. e. at the population or community level). However, monitoring aquatic communities is labour intensive and inadequate for the early detection of impacts. Research is needed to identify links between the bioassessment measures used, so that changes at the lowest biological level (e. g. using biomarkers and bioassays) can be translated into likely‘real’ impacts on the aquatic system, as measured at the population or community level. Monitoring the genetic structure of populations of aquatic organisms, particularly invertebrates, may provide a potential link between subtle effects observed in bioassay tests and subsequent changes in population density and/or community structure. A streamlined approach to monitoring changes at the community level needs to be developed to improve predictive ability and to make this approach more responsive to the early detection and prevention of unacceptable impacts. In addition, research on the use of ecosystem level parameters, such as production/respiration ratios or community metabolism, should be undertaken to determine their suitability for routine biomonitoring of water quality in Australian inland waters.
An examination of observer bias as a source of error in surveys of seagrass shoots
Authors: INGLIS GRAEME J. , SMITH MARCUS P. LINCOLN
Published: July 2006

Abstract
Mensurative experiments investigated the effects of different observers on estimates of the density of shoots of two species of seagrass: Posidonia australis Hook and Zostera capricorni Aschers. Balanced programmes of sampling were used to examine variation in counts of seagrass shoots attributable to different observers, sizes of quadrats, depths and locations within large beds of each species of seagrass. A separate experiment examined differences between novice observers and a more experienced observer, when an ‘optimal’ size of sampling unit was used. Estimated densities of Zostera shoots varied inconsistently among observers, quadrats, depths and locations. Differences between observers were not affected by the size of quadrat used to count Posidonia shoots, but varied between locations in the seagrass bed. Experience had only a minor impact on biases. Only two of 12 novices produced counts that were different from the experienced observer. These results emphasize the importance of considering both accuracy and precision in the design of field studies of seagrasses.
Effects of fire frequency on plant species composition of sandstone communities in the Sydney region: Combinations of inter‐fire intervals
Authors: CARY GEOFFREY J. , MORRISON DAVID A.
Published: July 2006

Abstract
Fire frequency is the number of fires experienced by a particular community within a given time period. This variable can potentially be resolved into a number of interacting components, including time since the most recent fire, and the length of the inter‐fire intervals. We estimated the effects of inter‐fire intervals and sequences of inter‐fire intervals, independently of time‐since‐fire, on the floristic composition of 26 samples from dry sclerophyll vegetation with different fire histories in Brisbane Water National Park near Sydney. In particular, we examined the effects in the recent fire history of: the length of the shortest inter‐fire interval (1–26 years); repetition of very short (1–3 years) and medium (7–14 years) inter‐fire intervals; and recovery from very short (1–3 years) and short (4–6 years) inter‐fire intervals. Our analyses suggest that inter‐fire interval may account for about 55% of the floristic variation among our samples, which were taken at a uniform 18 months after the most recent fire. There appear to be at least three general and unrelated effects of the recent history of inter‐fire intervals on the floristic composition of this vegetation: (i) shorter inter‐fire intervals were associated with a reduction in the number of species present in the community, along with a more unequal abundance of the remaining species, particularly of those large Proteaceae shrubs that often dominate the community biomass in dry sclerophyll shrublands of southeastern Australia; (ii) the presence of an inter‐fire interval that is 1–6 years long was associated with an additional reversible reduction in the number of fire‐sensitive species present in the community, particularly those common shrub species with a canopy‐stored seed‐bank and non‐leguminous species with a soil‐stored seed‐bank; and (iii) repetition of inter‐fire intervals that are 1–5 years long was associated with an increase in the abundance of herbaceous fire‐tolerant species. This means that variation in these characteristics is associated with changes in abundance of different plant species, and that the floristic composition of any one area can be influenced in three different ways by these variables. Management of fire for plant species conservation must therefore be based on both length of time‐since‐fire and length of inter‐fire intervals if it is to be effective.
Habitat utilization patterns of sympatric populations of Pseudomys gracilicaudatus and Rattus lutreolus in coastal heathland: A multivariate analysis
Authors: HAERING RON , FOX BARRY J.
Published: July 2006

Abstract
Habitat usage characteristics of two species of native murid rodents, Pseudomys gracilicaudatus and Rattus lutreolus were investigated on an area of coastal heathland at Myall Lakes National Park. A grid of 151 trap stations comprising 17 traplines was positioned across a mosaic of habitats. At each trap station 19 structural vegetation and physical variables known to affect the microdistribution of small mammals were measured. Multivariate statistical procedures identified those microhabitat variables that contribute to individual species' habitat use and habitat partitioning, and reduce potential competition for space. Cluster analysis classified trap stations into one of six habitat types that were mapped on the study area, identifying a heterogeneous assemblage of interlocking habitats. The pattern is a consequence of topographic variation on the site and, to a lesser extent, its fire history. Trapping results show P. gracilicaudatus and R. lutreolus exhibit similar macrohabitat selection, preferring topographically low habitats, with both species predominantly occupying short dense heath with dense sedge cover. The high overlap in macrohabitat use is greatly reduced when considered trap station by trap station, so that discriminant function and multiple regression analyses demonstrate marked microhabitat selection. Elevation was a highly significant variable, accounting for 41% and 27% of the variance in the habitat used by P. gracilicaudatus and R. lutreolus, respectively. This variable represents a soil moisture gradient that determines changes in the floristic and structural components of the biotic environment. Two other structural vegetation variables and vegetation height contributed 30% of the variance in P. gracilicaudatus distribution. Sedge cover was found to be significant and explained 13% of the variance in R. lutreolus distribution. Within‐habitat separation was explained best with a linear combination of variables in a discriminant function, rather than by any single variable. Differential microhabitat selection, interference competition and diet separation appear to be the major factors facilitating coexistence of these two species.
Palaeontology., adaptation and community ecology: A response to Walter and Pater son (1994)
Authors: Andersen Alan N.
Published: July 2006

AbstractThis paper challenges Walter and Paterson's (1994) assertion that the community concept ought to be abandoned because of recent palaeontological evidence pointing to the ‘individualistic’ nature of biological communities. The ‘individualistic’ versus ‘superorganismic’ community concepts might provide good grist for the philosophical mill, but have little practical relevance to contemporary community ecology. Ecologists define communities in terms of current species distributions and interactions, and seek to integrate the roles of both biotic and abiotic factors influencing species distributions. There is no assumption of tight co‐evolution among component species; Walter and Paterson confuse ‘organization’ with ‘co‐adaptation’. Nor, contrary to the authors’ claims, is there an implicit assumption that all community patterns are caused by competition. For most ecologists, the ‘competition debate’ ended a decade ago. Walter and Paterson's view that competition is rarely, if ever, important in structuring communities is not even held by the main protaganists of the ‘competition is not so important’ school of the 1980s, and is in direct contradiction of the extensive, more recent literature on the subject. It entirely ignores plant ecology. Many of Walter and Paterson's misunderstandings appear to arise from the false premise that explanation of adaptation should be the ultimate goal of any ecological discipline. The authors are hostile to community ecology because, if communities are individualistic, then little light can be shed on species adaptations. Fortunately, most ecologists are not so preoccupied with adaptation.
Leaf dynamics and insect herbivory in aEucalyptus camaldulensisforest under moisture stress
Authors: STONE C. , BACON P. E.
Published: July 2006

AbstractThe influence of soil moisture content on leaf dynamics and insect herbivory was examined between September 1991 and March 1992 in a river red gum (Eucalyptus camaldulensis) forest in southern central New South Wales. Long‐term observations of leaves were made in trees standing either within intermittently flooded waterways or at an average of 37. 5m from the edge of the waterways. The mean soil moisture content was significantly (P≤0.05) greater in the waterways than in the non‐flooded areas. Trees in the higher soil moisture regime produced significantly larger basal area increments and increased canopy leaf area. This increase in canopy leaf area was achieved, in part, through a significant increase in leaf longevity and mean leaf size. Although a greater number of leaves was initiated and abscissed per shoot from the non‐flooded trees, more leaves were collected from litter traps beneath the denser canopies of the flooded trees. Consumption of foliage by insects on the trees subjected to flooding compared to the non‐flooded trees was not significantly different. However, the relative impact of insect herbivory was significantly greater on the non‐flooded trees. Leaf chewing was the most common form of damage by insects, particularly Chryso‐melidae and Curculionidae. No species was present in outbreak during this study. Leaf survival decreased as the per cent area eaten per leaf increased. In addition, irrespective of the level of herbivory, leaf abscission tended to be higher inE. camaldulensisunder moisture deficit. The influence of soil moisture content on the balance between river red gum growth and insect herbivory is discussed.
The effect of fire and ants on the seed‐bank of a shrub in a semi‐arid grassland
Authors: HARRINGTON GRAHAM N. , DRIVER MARTIN A.
Published: July 2006

AbstractInvasion of grasslands by woody plants following the introduction of domestic stock is a worldwide phenomenon. Burning is frequently recommended as a remedial measure but for a pastoral enterprise it is costly and the frequency of the fires required is of critical economic importance. The size and longevity of the soil seed‐bank is an essential part of the response of shrub populations to prescribed fire regimes. In this study the seed‐bank of the semi‐arid zone shrubDodonaea attenuatainEragrostis eriopodatussock grassland was examined in relation to harvesting by ants and the burning history of the sites. On unburnt sites, more than 3500 seeds per m2 entered the seed‐bank in the summer 1984–85 but sites burnt 5 years previously produced less than one‐third of that number. Burnt shrubs did not flower for 5 years and no seeds survived in the soil through to 1985. Burning immediately prior to seed ripening destroyed the seed crop but burning after seed‐fall stimulated a greater germination in the following spring than on unburnt treatments. Ants rapidly harvested most of the seeds produced and after 20 months the combined effects of ant harvesting and germination had reduced the seed‐bank at unburnt sites to 8–21 seeds per m2 and at sites burnt 7 years previously to less than two seeds per m2. Seeds were initially harvested in summer by Pheidole spp. of ants for their elaiosome and then discarded in middens outside the entrance to the ant nest. During the subsequent cool season the seeds were taken back into the nest and stored at depths ranging from 2 to 30cm. It was concluded that ants provided short‐range dispersal (< 10 m) and promoted the contagious distribution ofD. attenuata, which is advantageous for a fire‐susceptible, arid‐zone shrub invading a grassland liable to be burnt: seedlings derived from seeds in ant storage chambers near the soil surface and in sparse grass situations caused by competition from shrubs may obtain some survival advantage. Prescribed fire has potential as a management tool for controlling population density ofD. attenuatabecause, depending upon season and frequency, it reduces seed rain by killing shrubs, suppresses flowering activity and destroys seed crops on the plant. Under the influence of a regime of regular burning, such as prevailed prior to the European pastoral industry, the limited soil seed‐bank would have been a major constraint onD. attenuatapopulations.
Comparison of regeneration following burning, clearing or mineral sand mining at Tomago, NSW: I. Structure and growth of the vegetation
Authors: FOX BARRY J. , FOX MARILYN D. , TAYLOR JENNIFER E. , JACKSON G. P. , SIMPSON JOHN , HIGGS PETER , REBEC LOUISA , AVERY RONALD
Published: July 2006

Abstract
We have begun a long‐term ecological research project to address questions about the impact of multiple disturbances on the species richness of communities and whether multiple disturbances are additive or interactive. A protected water catchment area was chosen, which is subjected to fires, sand mining and clearing, and for which detailed records are available. The study area, at Tomago (32°52′S, 151°45′E), has forest, woodland, shrubland and swamp on a sand substrate, with the vegetated dunes forming part of a coastal embayment. Forty‐four sites were located in forested areas that had undergone disturbance by either fire, sand mining or clearing. Sites of each disturbance type were grouped into four age classes: less than 1 year since disturbance, nominally 1991; 5 years, nominally 1986; 11 years, nominally 1980; and 17 years, nominally 1974. A set of burned sites, with the time of the last fire matched to the times of the other disturbances, was used as the control response. In this paper we describe the study area and sites, then examine the effects of each single disturbance on vegetation structure. Canopy cover increased with time and type of disturbance, with 17 year old cleared or mined sites similar to the cover of 11 year old burned sites. In the first two years after disturbance, burned sites had significantly more understorey vegetation than cleared or mined sites, but by 5 years all three were similar. The data presented here show that regeneration of mined sites at Tomago is substantially slower than regeneration following disturbance by fire, with the regeneration of cleared sites intermediate but closer to mining than fire. After 17 years regeneration, cleared and sand mined sites had not returned to the vegetation structure of the pre‐disturbance state. Understorey height and the amount of vegetation on cleared or mined sites have not achieved the levels in the original forest, although canopy cover did seem to have reached pre‐disturbance levels. Current rehabilitation techniques are more sophisticated than those used 17 years ago and continued monitoring of sites currently being rehabilitated may show a faster return to pre‐disturbance states. Having established the hierarchy and nature of the response to each single disturbance here, we are now in a position to investigate the impact of multiple disturbances.
Vertebrate‐dispersed species in a fire‐prone environment
Authors: FRENCH KRISTINE , WESTOBY MARK
Published: July 2006

Abstract
It is hypothesized that plant species that produce vertebrate‐dispersed seeds (fleshy fruits and brightly coloured arillate seeds) would not be common in fire‐prone vegetation because seeds are deposited on the soil surface and are unlikely to survive fires. They have not previously been known to have any means of burial that would enable them to await the next fire as a buried soil seed‐bank. We studied vertebrate‐dispersed species in fire‐prone sclerophyll vegetation to look at mechanisms used by vertebrate‐dispersed plants for persisting in these environments. Seeds do not survive heating to 150°C, although species from fire‐prone environments are more likely to tolerate moderate heating (80°C) without affecting viability than vertebrate‐dispersed species from environments where fire is rare. Most vertebrate‐dispersed species have the capacity to regenerate vegetatively, although they are not more likely to have this strategy than ant‐dispersed species. Finally, ants do take vertebrate‐dispersed seeds and fruits (particularly small ones) indicating the potential for the formation of a soil seed‐bank. Some species only persist in fire‐prone environments by recolonizing from unburnt areas.
Potential food resources available to malleefowl Leipoa ocellata in marginal mallee lands during drought
Authors: HARLEN RUSSELL , PRIDDEL DAVID
Published: July 2006

Abstract
Prime mallee lands that once supported high densities of malleefowl, Leipoa ocellata in New South Wales have been extensively cleared for agriculture. Malleefowl are now restricted largely to more and habitat. Given the added competition from introduced herbivores, there is concern that these marginal habitats may not contain sufficient food resources to support viable populations of malleefowl, particularly in times of drought. An opportunistic feeding strategy and omnivorous diet enable malleefowl to exploit a diverse array of food items. Vegetative and invertebrate food resources available to malleefowl in marginal mallee lands were monitored over a period of 1 year during drought. Food resources were varied, transient and patchily distributed. Composition and abundance fluctuated considerably, but potential food was never entirely absent. Despite the prevailing drought, food was obtainable throughout the year provided malleefowl adapted to the fluctuating availability of each of the various potential food resources. Reduced food resources in marginal habitat is not implicated as a major factor in the demise of the malleefowl. Food was most abundant between August and November, inclusive, due largely to the abundance of herbs, the diverse supply of buds, flowers and fruit on perennial shrubs, and the sporadic proliferation of cockroaches. Food availability was least, and therefore most critical, during February, March and June. The most favourable time of the year, in terms of available food resources, for the release of captive‐bred individuals was during spring, around September.
Field experiments on the effect of ticks on breeding success and chick health of cattle egrets
Authors: McKILLIGAN N. G.
Published: July 2006

Abstract
Two experiments compared broods that were naturally tick‐infested with an equal number that were rendered tick‐free by application of an acaricide to their nests and of barriers against further infestation. In the first experiment conducted in 1991–92 nestlings in tick‐infested broods had up to 159 larval ticks at once and a mean infestation of 23.6 larval ticks per chick per day. The chick's mean tick load was inversely correlated with its longevity. Chicks that survived to at least 18 days post‐hatching had significantly lower larval tick loads than those that died by 18 days, excluding the third‐hatched chick in each brood whose survival rate was low irrespective of tick‐infestation. At 7 days post‐hatching, tick‐infested chicks had a lower haematocrit and higher polychromasia than tick‐free chicks. I infer that blood loss anaemia caused the deaths of tick‐infested chicks in their first week. None died in their second week and the demise of those in their third week may have been due to the paralysis manifested prior to their death. I conclude that heavy tick infestation of their chicks reduced the breeding success of the parent egrets below that of the egrets whose chicks were kept free of ticks. In the second experiment in the 1992–93 season the mean level of tick infestation was much lower (5.1 per chick) and these chicks survived equally with tick‐free chicks through fledging.
Fertilizer impacts on the understorey of a regenerating Mountain Ash (Eucalyptus regnans F. Muell.) forest, Victoria
Authors: WANG LIANGMIN , ATTIWILL PETER M. , ADAMS MARK A.
Published: July 2006

Abstract
We examined the effects of adding fertilizers on nutrient concentrations in foliage, and on species composition and density of the understorey in a 10 year old Mountain Ash (Eucalyptus regnans F. Muell.) forest. Nutrient concentrations in foliage of three woody understorey species (Acacia dealbata, Pomaderris aspera and Olearia argophylla) showed no significant response to the addition of phosphorus and nitrogen either alone, in combination or combined with other nutrients. The phosphorus concentration in foliage and stems of two herbaceous species (Australina pusilla and Urtica incisa) was significantly increased by applying phosphorus. The addition of fertilizers had no significant effect on species composition and density of the understorey.
Tree seed germination and seedling establishment in treefall gaps and understorey in a subtropical forest of northeast India
Authors: RAO P. , BARIK S. K. , PANDEY H. N. , TRIPATHI R. S.
Published: July 2006

Abstract
Seed germination, and survival and growth of seedlings of four dominant tree species, Quercus dealbata, Quercus griffithii, Quercus glauca and Schima khasiana were studied in the treefall gaps and forest understorey of an undisturbed mature‐phase humid subtropical broadleaved forest in northeast India. Three important microenvironmental factors namely photosynthetically active radiation (PAR), soil moisture and litter depth, were also measured in the forest understorey and gaps and correlated with seedling mortality. Seed germination of S. khasiana was significantly higher in the treefall gaps than in the understorey; among the tree species studied, it had the highest germination. Quercus seedlings were abundant in the understorey and small gaps, while S. khasiana seedlings were more numerous in the large gaps. The survivorship curves for the seedling populations revealed that the three Quercus species survived better in the understorey, while S. khasiana did so in the gaps. PAR and soil moisture were positively correlated with tree seedling mortality, which occurred mainly during the winter months. The Quercus seedlings grew better in the forest understorey and small gaps and S. khasiana seedlings in the large gaps. The differential performance of the tree seedlings to the conditions prevailing in the understorey and gaps of two sizes indicates that different species were adapted to different light environments depending upon their optimum requirements. This could be an effective mechanism for promoting species coexistence in the forest community.
Introduced animals and their parasites: The cane toad,Bufo marinus, in Australia
Authors: BARTON DIANE P.
Published: July 2006

AbstractThe impact of introducing animals into an established ecosystem can be directly observed through predator‐prey and competition interactions. The impact of animalsviamore obscure relationships, such as the host‐parasite relationship, are generally not considered. The cane toadBufo marinus(Linnaeus) was introduced to Australia in 1935. Despite intensive research into many aspects of the biology of the toad, there has been no systematic survey of the parasite fauna ofB. marinusin Australia. It is unknown exactly what parasites the toad may have introduced to Australia and also the range of parasites that may have adapted to the toad from native fauna since its introduction. The provisional conclusion from this review is that all the helminth parasites so far recorded fromB. marmusin Australia have been acquired from local hosts. The interaction of toads and nativa faunaviatheir parasites remains unknown.