191 resultados para Shrub species


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To eradicate a weed incursion, its extent must be delimited and each infestation extirpated. Measures for delimitation and extirpation are utilized to assess the progress of eradication programs currently targeting three melastome shrub species (Clidemia hirta, Miconia nervosa and M. racemosa) in north-eastern Australia. The main infested area for each species was determined during the year after initial detection, but expanded surveys have led to the discovery of isolated, smaller outlying patches. Programs are refining survey methods (including search frequency) to prevent reproduction. Weed incursions that are limited to single infestations represent a prime opportunity for eradication. However, population and dispersal data indicate that eradication will require an ongoing investment for some time for all three species. Highly persistent seed and dispersal by frugivores suggest that eradication may prove extraordinarily difficult should any of these species spread or be discovered at more locations.

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Vertebrate fauna was studied over 10 years following revegetation of a Eucalyptus tereticornis ecosystem on former agricultural land. We compared four vegetation types: remnant forest, plantings of a mix of native tree species on cleared land, natural regeneration of partially cleared land after livestock removal, and cleared pasture land with scattered paddock trees managed for livestock production. Pasture differed significantly from remnant in both bird and nonbird fauna. Although 10 years of ecosystem restoration is relatively short term in the restoration process, in this time bird assemblages in plantings and natural regeneration had diverged significantly from pasture, but still differed significantly from remnant. After 10 years, 70 and 66% of the total vertebrate species found in remnant had been recorded in plantings and natural regeneration, respectively. Although the fauna assemblages within plantings and natural regeneration were tracking toward those of remnant, significant differences in fauna between plantings and natural regeneration indicated community development along different restoration pathways. Because natural regeneration contained more mature trees (dbh > 30 cm), native shrub species, and coarse woody debris than plantings from the beginning of the study, these features possibly encouraged different fauna to the revegetation areas from the outset. The ability of plantings and natural regeneration to transition to the remnant state will be governed by a number of factors that were significant in the analyses, including shrub cover, herbaceous biomass, tree hollows, time since fire, and landscape condition. Both active and passive restoration produced significant change from the cleared state in the short term.

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Melaleuca densispicata Byrnes is an uncommon species with a limited distribution, comprising disjunct populations in inland southern Queensland and northern New South Wales, Australia. It is a dense, woody shrub, 2–4 m in height, which exhibits a marked 'clumping' growth habit. It has thick, papery bark and displays many white flowers during spring or early summer. Although it has long been known to exist, M. densispicata was only formally described in 1984, and very little is currently known about its ecology or specific management requirements. There are only seven known subpopulations of the species across its range. A major population at the western limit of its distribution occurs on Currawinya National Park (28°52'S, 144°30'E). Here, it is locally abundant and listed as a noteworthy plant species under the Management Plan (Queensland Parks & Wildlife Service 2001). This study aimed to identify patterns in the distribution of M. densispicata in Currawinya National Park, describe its ecological niche and role, and provide management recommendations for the species within the study area. Recent anecdotal observations of recruitment failure in south-western Queensland (Peter McRae, QPWS, October 2004, pers. comm.; Dick O'Connell, local grazier, July 2005 pers. comm.) caused additional emphasis to be placed on the examination of recruitment and recruitment factors.

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Invasive bird-dispersed plants often share the same suite of dispersers as co-occurring native species, resulting in a complex management issue. Integrated management strategies could incorporate manipulation of dispersal or establishment processes. To improve our understanding of these processes, we quantified seed rain, recruit and seed bank density, and species richness for bird-dispersed invasive and native species in three early successional subtropical habitats in eastern Australia: tree regrowth, shrub regrowth and native restoration plantings. We investigated the effects of environmental factors (leaf area index (LAI), distance to edge, herbaceous ground cover and distance to nearest neighbour) on seed rain, seed bank and recruit abundance. Propagule availability was not always a good predictor of recruitment. For instance, although native tree seed rain density was similar, and species richness was higher, in native plantings, compared with tree regrowth, recruit density and species richness were lower. Native plantings also received lower densities of invasive tree seed rain than did tree regrowth habitats, but supported a similar density of invasive tree recruits. Invasive shrub seed rain was recorded in highest densities in shrub regrowth sites, but recruit density was similar between habitats. We discuss the role of microsite characteristics in influencing post-dispersal processes and recruit composition, and suggest ways of manipulating these processes as part of an integrated management strategy for bird-dispersed weeds in natural areas.

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The ecology of the uncultured, but large and morphologically conspicuous, rumen bacterium Oscillospira spp. was studied. Oscillospira-specific 16S rRNA gene sequences were detected in North American domestic cattle, sheep from Australia and Japan, and Norwegian reindeer. Phylogenetic analysis of the sequences obtained allowed definition of three operational taxonomic units within the Oscillospira clade. Consistent with this genetic diversity, we observed atypical smaller morphotypes by using an Oscillospira-specific fluorescence in situ hybridization probe. Despite the visual disappearance of typical large Oscillospira morphotypes, the presence of Oscillospira spp. was still detected by Oscillospira-specific PCR in the rumen of cattle and sheep. These observations suggest the broad presence of Oscillospira species in various rumen ecosystems with the level, and most likely the morphological form, dependent on diet. An ecological analysis based on enumeration of the morphologically conspicuous, large-septate form confirms that the highest counts are associated with the feeding of fresh forage diets to cattle and sheep and in two different subspecies of reindeer investigated.

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In the coastal region of central Queensland female red-spot king prawns, P. longistylus, and the western or blue-leg king prawns, P. latisulcatus, had high mean ovary weights and high proportions of advanced ovary development during the winter months of July and August of 1985 and 1986. On the basis of insemination, both species began copulating at the size of 26-27 mm CL, but P. longistylus matured and spawned at a smaller size than P. latisulcatus. Abundance of P. longistylus was generally three to four times greater than that of P. latisulcatus but the latter was subject to greater variation in abundance. Low mean ovary weight and low proportions of females with advanced ovaries were associated with the maximum mean bottom sea-water temperature (28.5ºC) for both species. Population fecundity indices indicated that peaks in yolk or egg production (a) displayed a similar pattern for both species, (b) varied in timing from year to year for both species and (c) were strongly influenced by abundance. Generally, sample estimates of abundance and commercial catch rates (CPUE) showed similar trends. Differences between the two may have been due to changes in targeted commercial effort in this multi-species fishery.

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Yelsemia lowrieana sp . nov. (Ustilaginomycetes) is described and illustrated from Byblis rorida collected in northwestern Western Australia. Infected plants had galls filled with spores on stems and pedicels. The spores were unusual in that each could be separated from a dark outer spore wall. This is the first record of a smut fungus on the dicotyledonous host family Byblidaceae.

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Five species of commercial prawns Penaeus plebejus, P. merguiensis, P. semisulcatus/P. esculentus and M. bennettae, were obtained from South-East and North Queensland, chilled soon after capture and then stored either whole or deheaded on ice and ice slurry, until spoilage. Total bacterial counts, total volatile nitrogen, K-values and total demerit scores were assessed at regular intervals. Their shelf lives ranged from 10-17 days on ice and >20 days on ice slurry. Initial bacterial flora on prawns from shallower waters (4-15m) were dominated by Gram-positives and had lag periods around 7 days, whereas prawns from deeper waters (100m) were dominant in Pseudomonas spp. with no lag periods in bacterial growth. The dominant spoiler in ice was mainly Pseudomonas fragi whereas the main spoiler in ice slurry was Shewanella putrefaciens. Bacterial interactions seem to play a major role in the patterns of spoilage in relation to capture environment and pattern of storage

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Five new species of the flightless scarabaeine genus Aptenocanthon Matthews are described from northern Australia: jimara sp. nov. from the Northern Territory; kabura sp. nov., wollumbin sp. nov., winyur sp. nov. and speewah sp. nov. from mountains in the wet tropics of northern Queensland. A key is given to the eight species in the genus. A. jimara is the first record of the genus away from the east coast. Biology and distribution are discussed.

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Aptenocanthorn monteithi sp. Nov. is described from Atherton Tableland areas in northern Queensland. The nearest relatives are from mountains in eastern New South Wales.

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Twenty new Australian species of the scarabaeine genus Onthophagus Latreille are described: O. arkoola, O. beelarong, O. bindaree, O. binyana, O. bundara, O. cooloola, O. dinjerra, O. godarra, O. gurburra, O. kakadu, O. mije, O. mongana, O. pinaroo, O. trawalla, O. weringerong, O. williamsi, O. worooa, O. yackatoon, O. yaran, O. yourula. Notes and scanning electron micrographs are given to assist in the separation of each from previously described Australian species. Distribution maps are provided for each species

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Aulacopris mallhewsi sp. nov. is described from mountains behind Cape Tribulation in northern Queensland. Its nearest relatives are in southeastern Queensland. The species is the smallest in the genus and is flightless. Individuals engaged in ball making and ball rolling activities in the laboratory.

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Six new species of Onthophagus are described from Queensland and Northern Territory: 0. kiambram. 0. yarrumba, 0. kora, O.punthari, 0. terrara and 0. wanappe. All six species are related to the Australian 0. rubescens Macleay, and a key is given to separate the 14 species in that group.

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A new tribe, the Stereomerini, is established for four unusual genera: Stereomera Arrow, Termitaxis Krikken, Australoxenella n.gen., and Bruneixenus n.gen. The previously described genera are monotypic, as is Bruneixenus, the type species being B. squamosus n.sp. from Brunei. Australoxenella contains two new species, A. humptydooensis, type species, and A. bathurstensis, both from the Northern Territory, Australia. The relationships of the new tribe are analyzed and compared with the most closely related tribe, the Rhyparini, in the Aphodiinae. The tribe Rhyparini is redefined, and the genus Notocaulus Quedenfeldt is transferred to the Eupariini. A key to genera in both the Stereomerini and the Rhyparini is presented, important characters are illustrated, a cladogram is given, and convergence is discussed.

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Recolonisation and succession in a multi-species tropical seagrass meadow was examined by creating gaps (50×50 cm) in the meadow and manipulating the supply of sexual and asexual propagules. Measurements of leaf shoot density and estimates of above-ground biomass were conducted monthly to measure recovery of gaps between September 1995 and November 1997. Measurements of the seeds stored in the sediment (seed bank) and horizontal rhizome growth of colonising species were also conducted to determine their role in the recovery process. Asexual colonisation through horizontal rhizome growth from the surrounding meadow was the main mechanism for colonisation of gaps created in the meadow. The seed bank played no role in recolonisation of cleared plots. Total shoot density and above-ground biomass (all species pooled) of cleared plots recovered asexually to the level of the undisturbed controls in 10 and 7 months, respectively. There was some sexual recruitment into cleared plots where asexual colonisation was prevented but seagrass abundance (shoot density and biomass) did not reach the level of unmanipulated controls. Seagrass species did not appear to form seed banks despite some species being capable of producing long-lived seeds. The species composition of cleared plots remained different to the undisturbed controls throughout the 26-month experiment. Syringodium isoetifolium was a rapid asexual coloniser of disturbed plots and remained at higher abundances than in the control treatments for the duration of the study. S. isoetifolium had the fastest horizontal rhizome growth of species asexually colonising cleared plots (6.9 mm day−1). Halophila ovalis was the most successful sexual coloniser but was displaced by asexually colonising species. H. ovalis was the only species observed to produce fruits during the study. Small disturbances in the meadow led to long-term (>2 years) changes in community composition. This study demonstrated that succession in tropical seagrass communities was not a deterministic process. Variations in recovery observed for different tropical seagrass communities highlighted the importance of understanding life history characteristics of species within individual communities to effectively predict their response to disturbance. A reproductive strategy involving clonal growth and production of long-lived, locally dispersed seeds is suggested which may provide an evolutionary advantage to plants growing in tropical environments subject to temporally unpredictable major disturbances such as cyclones