bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of soil salinity on plant distribution and production at Loburu delta, Lake Bogoria National Reserve, Kenya
Authors: Onkware Augustino Osoro 
Published: March 2003

AbstractA study was carried out at Loburu delta, Lake Bogoria National Reserve, Kenya, on the effect of different levels of soil salinity and moisture on plant species distribution, production, reproductive strategy and litter decomposition. The soils are coarse and vary significantly in levels of salinity and moisture. The highest salinity was greater than 3.0 S/m, ECe. Soil moisture was significantly higher in the more saline than non‐saline or low salinity soils because of ground seepage. Sixteen plant species were collected but only Sporobolus spicatus and Cyperus laevigatus were determined to be true halophytes. Biomass and above‐ground production were significantly higher in the high and medium saline soils than the non‐saline or hyper‐saline soils (>3.0 S/m, Ece). Precipitation promoted various aspects of production in both halophytes at various levels of salinity. Soil salinity did not influence biomass allocation to reproductive structures but precipitation enhanced allocation to stolons in Sporobolus spicatus. The dead plant mass was significantly higher than biomass at all salinities, which indicated low grazing pressure at the site. Litter decomposition was only marginally reduced by high soil salinity. It was concluded that low moisture limits biomass and production on the non‐saline soils and salinity is responsible for low production in the hyper‐saline soils.
Pseudoreplication in experimental designs for the manipulation of seed germination treatments
Authors: Morrison David A. , Morris E. Charles 
Published: March 2003

AbstractIn the published reports concerning the design of laboratory experiments examining signals that might trigger seed germination, there is currently a misunderstanding of what might constitute correct replication of the experimental treatment. This is particularly true for the study of dry heat, smoke and charcoal, where either an individual seed or a batch of seeds in a Petri dish or tray is being treated as the unit of replication of the experimental treatment, irrespective of whether or not those seeds were all subjected to the experimental manipulation simultaneously. Under these circumstances, the application of the treatment is unreplicated, while samples nested within that single application have been replicated, and the Petri dishes/trays are functioning solely as independent replicates of the variability in germination response within the seed batch used and variation within the pretreatment and post‐treatment environments. Thus any observed difference in germination may be due to the germination treatment but, potentially, it could also be due to any chance event affecting the treated sample. There are a number of alternative experimental designs that avoid this problem. The essential point with these designs is that the application of the experimental manipulation to each replicate should be separated in space by the use of separate experimental equipment and/or in time by the repeated use of the same experimental apparatus.
Retrospective monitoring of rangeland vegetation change: ecohistory from deposits of sheep dung associated with shearing sheds
Authors: Witt G. Bradd , Berghammer Lindi J. , Moll Robert J. S. Beeton and Eugene J. 
Published: March 2003

AbstractThis paper explores the potential of a new method of reconstructing historical vegetation change in the Australian rangelands. Historical monitoring of rangeland vegetation has been so deficient that it is not possible to determine whether a long‐term trend toward degradation has occurred (as is often assumed) or, indeed, if it is continuing to occur. Because long‐term records are unavailable any attempt to monitor vegetation retrospectively must be based on proxy measures rather than direct observation. Where historical data are lacking an integration of palaeoecological, archaeological and ecological methods is required to reconstruct the past. Our research is based on a detailed analysis of sheep faeces deposited near a shearing shed in the semiarid rangelands of south‐west Queensland between the late 1930s and the mid‐1990s. The faeces in these deposits represent the diet of sheep in the days leading up to the property’s annual shearing and as such are a potentially useful index to changes in vegetation. Results indicate significant changes in the diet of sheep since the late 1940s. The potential of this method, and its limitations, are discussed. Long‐term records are critical in understanding issues of sustainability in land management and it is intended that this paper will stimulate further research into historical vegetation change in rangelands.
Episodic seedling growth inAllosyncarpia ternata, a lignotuberous, monsoon rainforest tree in northern Australia
Authors: Fordyce I. R. , Eamus D. , Duff G. A. 
Published: March 2003

AbstractOn the western Arnhem Land Plateau, Northern Territory, Australia, seedlings of the canopy treeAllosyncarpia ternataS.T. Blake typically spend many years (perhaps decades) as small (<1 m), multistemmed plants on the forest floor. In this establishment phase, long periods of apparent inactivity are interrupted by episodes of rapid growth. This paper describes a 5‐year field‐monitoring program to examine the pattern of seedling growth and survival in allosyncarpia forest, and field and shadehouse measurements of lignotuber size. Individual seedlings may produce, each wet season, a number of fast‐growing stems, which then die back in the following dry season. As a result, mean annual above‐ground growth during this life stage is negligible. With each wet season, however, the seedling extends its below ground parts – a large lignotuber and a deep root system. After a number of years, when the lignotuber has grown large enough to sustain massive shoot growth, when a suitable light gap becomes available, and presumably when roots reach reliable dry‐season water supplies, the seedling grows rapidly. Thus, the shortage of saplings in allosyncarpia forest is due to the short time that individual plants spend at that particular growth‐stage, rather than to any dysfunction in recruitment.
Grazing effects on plant cover, soil and microclimate in fragmented woodlands in south‐western Australia: implications for restoration
Authors: Yates Colin J. , Norton David A. , Hobbs Richard J. 
Published: March 2003

AbstractThis study investigated the impacts of livestock grazing on native plant species cover, litter cover, soil surface condition, surface soil physical and chemical properties, surface soil hydrology, and near ground and soil microclimate in remnant Eucalyptus salmonophloia F. Muell woodlands. Vegetation and soil surveys were undertaken in three woodlands with a history of regular grazing and in three woodlands with a history of little or no grazing. Livestock grazing was associated with a decline in native perennial cover and an increase in exotic annual cover, reduced litter cover, reduced soil cryptogam cover, loss of surface soil microtopography, increased erosion, changes in the concentrations of soil nutrients, degradation of surface soil structure, reduced soil water infiltration rates and changes in near ground and soil microclimate. The results suggest that livestock grazing changes woodland conditions and disrupts the resource regulatory processes that maintain the natural biological array in E. salmonophloia woodlands. Consequently the conditions and resources in many remnant woodlands may be above or below critical thresholds for many species. The implications of these findings for restoration of plant species diversity and community structure are discussed. Simply removing livestock from degraded woodlands is unlikely to result in the restoration of plant species diversity and community structure. Restoration will require strategies that capture resources, increase their retention and improve microclimate.
Smoke and heat effects on soil seed bank germination for the re‐establishment of a native forest community in New South Wales
Authors: Read T. R. , Bellairs S. M. , Mulligan D. R. , Lamb D. 
Published: March 2003

AbstractThe effects of plant‐derived smoke and of heat on the emergence of seedlings from seeds were assessed. Seeds had been stored in forest topsoil used for mine site rehabilitation. The study was carried out in a dry sclerophyll, spotted gum (Corymbia maculata), forest community at the Mount Owen open‐cut coal mine in the Hunter Valley region of New South Wales. Samples of the surface 2.5 cm of topsoil were either exposed to cool smoke from eucalypt foliage for 60 min, heated to 80°C, or left untreated. Seedling emergence from the seed bank in this soil was then monitored in a glasshouse. Within the first month, smoke alone promoted a 4.3‐fold increase in the density of seedlings relative to control. There were 540 emergents per m2 in the control and 2309 per m2 in the smoke treated topsoil. Many annual and perennial herbs emerged but grasses responded most strongly to smoke. Germination in seven of the 20 grass species was promoted by smoke. Smoke promoted the germination of some introduced species as well as native species, and accelerated the rate at which seedlings emerged, although these differences sometimes declined with time. Heat also stimulated germination but smoke and heat stimuli appeared to be complementary in their promotion of seedling emergence from the topsoil seed bank. Each treatment increased the density of different species, enhanced the species richness of different components of the seed bank, and had different effects on the rate of emergence. The results suggest that increased seed germination in the field immediately following a moderate intensity fire may sometimes be the result of smoke stimulation and sometimes the result of heat stimulation of the soil seed bank. These findings may have important implications for minesite revegetation programs where topsoils are replaced after mining and rapid germination of seeds stored in these soils is required during short periods when conditions are favourable for germination.
Invasions: the perspective of diverse plant communities
Authors: Prieur‐Richard Anne‐Helene , Lavorel Sandra 
Published: March 2003

AbstractExotic plant invasions represent a threat to natural and managed ecosystems. Understanding of the mechanisms that determine why a given species may invade a given ecosystem, or why some biomes and regions seem more prone to invasions, is limited. One potential reason for this lack of progress may lie in how few studies have addressed invasion mechanisms from the point of view of the invaded community. On the other hand, the renewed debate about the relationship between ecological diversity and ecosystem stability offers the opportunity to revisit existing theory and empirical evidence, and to attempt to investigate which characteristics of plant communities, including their diversity, contribute to their invasibility. Empirical studies have shown both positive and negative relationships between species diversity of resident plant communities and their invasibility by external species. Rather than attempting to build a larger collection of case studies, research now needs to address the mechanisms underlying these relationships. Previous knowledge about the mechanisms favouring invasion needs to be coupled with community theory to form the basis of these new investigations. Modern community theory offers hypotheses and techniques to analyse the invasibility of communities depending on their diversity and other factors, such as species’ life histories and environmental variability. The body of knowledge accumulated in invasion ecology suggests that the role of disturbances, in interaction with fertility, and the importance of interactions with other trophic levels, are specific factors for consideration. In addition, it is essential for future studies to explicitly tease apart the effects of species richness per se from the effects of other components of ecological diversity, such as functional diversity (the number of functional groups) and trophic diversity (the number of interactions among trophic levels).
Arthropod responses to experimental fire regimes in an Australian tropical savannah: ordinal‐level analysis
Authors: Andersen Alan N. , MÜller Warren J. 
Published: March 2003

AbstractFire is widely used for conservation management in the savannah landscapes of northern Australia, yet there is considerable uncertainty over the ecological effects of different fire regimes. The responses of insects and other arthropods to fire are especially poorly known, despite their dominant roles in the functioning of savannah ecosystems. Fire often appears to have little long‐term effect on ordinal‐level abundance of arthropods in temperate woodlands and open forests of southern Australia, and this paper addresses the extent to which such ordinal‐level resilience also occurs in Australia’s tropical savannahs. The data are from a multidisciplinary, landscape‐scale fire experiment at Kapalga in Kakadu National Park. Arthropods were sampled in the two major savannah habitats (woodland and open forest) using pitfall traps and sweep nets, in 15–20 km2 compartments subjected to one of three fire regimes, each with three replicates: ‘early’ (annual fires lit early in the dry season), ‘late’ (annual fires lit late in the dry season), and ‘unburnt’ (fires absent during the five‐year experimental period 1990–94). Floristic cover, richness and composition were also measured in each sampling plot, using point quadrats. There were substantial habitat differences in floristic composition, but fire had no measured effect on plant richness, overall composition, or cover of three of the four dominant species. Of the 11 ordinal arthropod taxa considered from pitfall traps, only four were significantly affected by fire according to repeated‐measures
ANOVA. There was a marked reduction in ant abundance in the absence of fire, and declines in spiders, homopterans and silverfish under late fires. Similarly, the abundances of only four of the 10 ordinal taxa from sweep catches were affected by fire, with crickets and beetles declining in the absence of fire, and caterpillars declining under late fires. Therefore, most of the ordinal taxa from the ground and grass‐layer were unaffected by the fire treatments, despite the treatments representing the most extreme fire regimes possible in the region. This indicates that the considerable ordinal‐level resilience to fire of arthropod assemblages that has previously been demonstrated in temperate woodlands and open forests of southern Australia, also occurs in tropical savannah woodlands and open forests of northern Australia.
Predation by red foxes limits recruitment in populations of eastern grey kangaroos
Authors: Banks Peter B. , Newsome Alan E. , Dickman Chris R. 
Published: March 2003

AbstractWe investigated the impact of red fox (Vulpes vulpes Linnaeus 1758) predation on juvenile eastern grey kangaroos (Macropus giganteus Shaw 1790) using a replicated predator removal experiment. In two sites in Namadgi National Park, south‐eastern Australia, a persistent 1080 poisoning campaign over 18 months reduced fox density by more than 85%, and to less than 10% of the fox density in two other sites with no fox baiting. Changes in the mother : young ratios and densities of kangaroo populations were monitored twice monthly along 2‐km transects in each site from July 1993 to February 1995. Compared to nonremoval sites, where foxes were controlled, 25–40% more females retained juveniles over the period when these young became emergent from the pouch. This higher survival of emergent pouch young resulted in a significantly higher proportion of juveniles in kangaroo populations at fox control sites, which resulted in a significantly higher annual growth rate. We conclude that predation upon juveniles is an important limiting factor for kangaroo populations in Namadgi NP.
Diversity of insect‐induced galls along a temperature– rainfall gradient in the tropical savannah region of the Northern Territory, Australia
Authors: Blanche K. R. 
Published: March 2003

AbstractEvidence regarding the effect of temperature and rainfall on gall‐inducing insects is contradictory: some studies indicate that species richness of gall‐inducing insects increases as environments become hotter and drier, while others suggest that these factors have no effect. The role of plant species richness in determining species richness of gall‐inducing insects is also controversial. These apparent inconsistencies may prove to be due to the influence of soil fertility and the uneven distribution of gall‐inducing insect species among plant taxa. The current study tested hypotheses about determinants of gall‐inducing insect species richness in a way different to previous studies. The number of gall‐inducing insect species, and the proportion of species with completely enclosed galls (more likely to give protection against heat stress and desiccation), were measured in replicate plots at five locations along a 500‐km N‐S transect in the seasonal tropics of the Northern Territory, Australia. There is a strong temperature–rainfall gradient along this transect during the wet season. Plant species lists had already been compiled for each collection plot. All plots were at low elevation in eucalypt savannah growing on infertile soils. There was no evidence to suggest that hot, dry environments in Australia have more gall‐inducing insect species than cooler, wetter environments, or that degree of enclosure of galls is related to protecting insects from heat stress and desiccation. The variable number of gall‐inducing insect species on galled plant species meant that plant species richness did not influence gall species richness. Confirmation is still required that low soil fertility does not mask temperature–rainfall effects and that galls in the study region are occupied predominantly in the wet season, when the temperature–rainfall gradient is most marked.
Palaeo‐ecology of the Gap and Coturaundee Ranges, western New South Wales, using stick‐nest rat (Leporillus spp.) (Muridae) middens
Authors: Allen V. , Head L. , Medlin G. , Witter D. 
Published: March 2003

AbstractPollen, plant and animal macrofossils recovered from nine Leporillus spp. (Muridae) middens found in the Gap and Coturaundee Ranges, western New South Wales were examined. By comparing current vegetation, pollen from modern surface samples and pollen from midden samples, general vegetation characteristics over the last 6500 years
BP were reconstructed. Evidence shows that a greater shrub cover was apparent between 6500 and 5200
BP, while other aspects of the vegetation cover were similar to present. An increase in tree pollen, possibly indicating greater tree cover, occurred around 3400–2600
BP, while vegetation in the last 1300 years was similar to present. These interpretations, particularly from the older samples, are tentative due to spatial and temporal limitations. Animal macrofossils from the middens indicate that several mammal species now extinct or uncommon in western New South Wales have occurred in the area in the past 3000 years. This study also confirms that reconstruction of vegetation from Leporillus spp. midden evidence should be seen as separate ‘snapshots’, rather than continuous records over a stratigraphically defined timescale.
Swapping space for time and unfair tests of ecological models
Authors: Tyre Andrew J. , Tenhumberg Brigitte , Mccarthy Michael A. 
Published: March 2003

AbstractTesting ecological models for management is an increasingly important part of the maturation of ecology as an applied science. Consequently, we need to work at applying fair tests of models with adequate data. We demonstrate that a recent test of a discrete time, stochastic model was biased towards falsifying the predictions. If the model was a perfect description of reality, the test falsified the predictions 84% of the time. We introduce an alternative testing procedure for stochastic models, and show that it falsifies the predictions only 5% of the time when the model is a perfect description of reality. The example is used as a point of departure to discuss some of the philosophical aspects of model testing.
Roost preferences and foraging ranges of the eastern forest bat Vespadelus pumilus under two disturbance histories in northern New South Wales, Australia
Authors: Law Bradley S. , Anderson Jason 
Published: March 2003

AbstractLittle is known about the habitat requirements of Australian bats; however, this information is needed to make better‐informed decisions when systems are disturbed. This study contrasts the roosting and foraging ecology of the eastern forest bat Vespadelus pumilus (Vespertilionidae), one of Australia’s smallest bats, between two sites of differing disturbance history on the mid‐north coast of New South Wales. Lorne Flora Reserve (182 ha) is primarily old‐growth forest surrounded by regrowth forest and eucalypt plantations, while Swans Crossing is dominated by regrowth and eucalypt plantations established on part of an old dairy farm. A total of 38 bats were tracked during the maternity and mating seasons at the two sites. Roost preferences were determined by comparing trees used as roosts with those randomly available, while foraging bats were triangulated from fixed stations at night. Bats tracked at Lorne Flora Reserve typically roosted in hollows within large, mature trees and showed a strong preference for roosting and foraging (females only) within the Reserve. Lactating females at Swans Crossing roosted in hollows of remnant rainforest trees within a gully and dead eucalypts, while males often roosted in understorey trees (such as Acacia). Dead trees were frequently used as roosts at both sites. Under both disturbance histories, the mean distance of female maternity roosts from creeks was 20 m, indicating that riparian zones provide important roosting habitat for V. pumilus. However, roosts shifted to the mid‐slope prior to winter when bats mate. Retention of mature trees in a variety of topographic locations may allow behavioural adjustments with the seasons. Bats caught in the regrowth forest also foraged there, with foraging ranges averaging just 5.3 ha (n = 10), indicating that regrowth is used by this bat for both foraging and roosting.