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Land clearing in Australia's southwest has led to widespread salinisation of aquatic ecosystems. Four different ecological regimes (clear, submerged macrophyte-dominated; clear, benthic microbial community-dominated; turbid, phyto...
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Land clearing in Australia's southwest has led to widespread salinisation of aquatic ecosystems. Four different ecological regimes (clear, submerged macrophyte-dominated; clear, benthic microbial community-dominated; turbid, phytoplankton-dominated; and turbid, sediment-dominated) have previously been identified in the salinising wetlands of this region. Monitoring data from seven saline wetlands over an 18-month period were used to evaluate whether a continuum, simple threshold or alternative regimes conceptual model (sensu Hydrobiologia, 200/201, 1990, 367; Hydrobiologia, 200/201, 1990, 475) most appropriately represented transitions between these ecological regimes. The authors also aimed to identify whether factors other than salinity played a major role in defining ecological regimes or causing shifts between them. Ordination of biological variables revealed a separation of benthic microbial community-dominated from submerged macrophyte-dominated sites and times. The mean salinities of these two groups were very similar, suggesting that a salinity threshold was not responsible for benthic microbial versus macrophyte dominance. No other environmental variable was found to have a strong, direct influence on the groupings. The dynamics of regime change in saline wetlands appear not to be driven by any single variable, but by the combined effects of salinity and water regime on species life histories and competitive abilities. Macrophytes were powerful competitors, able to germinate and establish under a range of salinities, turbidities and water depths, and were favoured by seasonal drying. Data from the seven wetlands indicated that the continuum, simple threshold and alternative regimes conceptual models did not appropriately represent transitions between ecological regimes in seasonally drying wetlands. Macrophyte and benthic microbial regimes occurred at overlapping salinity levels, excluding both the continuum and threshold models, and the regular occurrence of drying appeared to preclude the alternative regimes model. Drying prevented the development of strong positive feedback mechanisms, which might otherwise have maintained the benthic microbial community-dominated regime. It is hypothesised that an alternative regimes model might still be valid for salinising ecosystems holding permanent water
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Significant rainfall declines have been observed across much of southern Australia over the last 50 years. In particular, strong declines occurred in the southwest of Western Australia (SWWA) from the late 1960s with further decli...
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Significant rainfall declines have been observed across much of southern Australia over the last 50 years. In particular, strong declines occurred in the southwest of Western Australia (SWWA) from the late 1960s with further declines in the late 1990s, and in the southwest of eastern Australia (SWEA) from the mid-1990s. As a result, most communities in these regions are facing water shortages. Meteorologically, the regions share a common winter-maximum rainfall regime, with peak rainfall occurring from May to October. In both regions, the declines have mainly occurred in the early part of the winter half-year (May-June-July, MJJ). This study aims to assess if there is an association between rainfall variability in these two regions on a range of time-scales and whether that association has altered with the recent rainfall declines. Rainfall variability in the two regions is significantly related. On synoptic time-scales, a weak but significant relationship was found in each month of the winter half-year due to rain-bearing disturbances travelling along the storm track affecting the two regions with a lag of approximately 3 days. On interannual time-scales, the relationship is stronger because of the high correlation between mean sea-level pressures (MSLP) over both regions. MJJ MSLP has seen significant increases over the last 50 years in both regions, reaching record values in 2006. In recent decades the interannual association between early winter rainfall totals has strengthened, however this is due in part to the decreasing variance at each location. The variability of the associations between these two regions provides a background on which to explore the strength and variability of the drivers that influence rainfall variability across southern Australia.
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Three new species are described, viz. E. vittata D.Nicolle, an obligate seeder previously confused with the respouter species E. sheathiana Maiden and also differing from the latter in the narrower adult leaves and smaller buds an...
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Three new species are described, viz. E. vittata D.Nicolle, an obligate seeder previously confused with the respouter species E. sheathiana Maiden and also differing from the latter in the narrower adult leaves and smaller buds and fruits; E. frenchiana D.Nicolle, an obligate seeder from between Norseman and Hyden, previously confused with E. corrugata Luehm. but most closely related to E. pterocarpa C.A.Gardner ex P.J.Lang and differing from the latter in the smaller leaves, buds and fruits and the hemispherical opercula; and E. distuberosa D.Nicolle, an obligate seeder previously confused with the respouter species E. pileata Blakely. Two subspecies are recognized in E. distuberosa, viz. subsp. distuberosa, of widespread but scattered distribution in the southern goldfields, and subsp. aerata D.Nicolle, restricted to Bronzite Ridge west of Norseman. A key to the obligate seeder taxa of E. ser. Rufispermae Maiden is provided.
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This paper examines the importance of the postwar settlement to Australian international policy. In particular, it considers how the postwar settlement of American regional primacy and economic dominance became built into the foun...
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This paper examines the importance of the postwar settlement to Australian international policy. In particular, it considers how the postwar settlement of American regional primacy and economic dominance became built into the foundations of Australian international engagement and its long-term consequences. The first part of the paper explains how this occurred and why it is so important to Australia's current policy dilemmas. The second part of the paper examines how changes to the fundamental structures of the 1945 regional strategic settlement, focusing primarily on Northeast Asia, are driving shifts in Australian policy. It concludes with a reflection on the choices Australia has made about its strategic future as it is heavily invested in the belief that U.S. primacy can endure over the long term.
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The nomenclature and typification of several species of Trymalium Fenzl is reviewed and a revised key to species and infraspecific taxa of the genus is presented. The name T. odoratissimum Lindl. is re-instated for T. floribundum ...
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The nomenclature and typification of several species of Trymalium Fenzl is reviewed and a revised key to species and infraspecific taxa of the genus is presented. The name T. odoratissimum Lindl. is re-instated for T. floribundum Reissek and the new combination T. odoratissimum subsp. trifidum (Rye) Kellermann, Rye & K.R.Thiele is made. Lectotypes are nominated for T. billardierei Fenzl var. tomentosum Reissek (= T. odoratissimum Lindl. subsp. odoratissimum) and T. urceolare (F.Muell.) Diels. A neotype is designated for T. litorale (Diels) Domin.
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Seagrass productivity, as leaf extension, was measured using the hole punch and needle punch techniques. These methods have been widely implemented to determine seagrass leaf extension rates, yet there is no evidence in the litera...
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Seagrass productivity, as leaf extension, was measured using the hole punch and needle punch techniques. These methods have been widely implemented to determine seagrass leaf extension rates, yet there is no evidence in the literature of a comparison between methods. The hole punch method involves removing part of the basal area of a seagrass leaf and it was proposed that this measurement technique may affect the leaf extension rates that are being measured. Leaf extension rates were measured in Posidonia sinuosa meadows off the coast of Perth, Western Australia. There were no significant differences in seagrass leaf extension between the two methods. The hole punch method is favoured, as measurement of incremental leaf growth is facilitated by the obvious hole left by the punch. The needle punch method leaves lesions on seagrass leaves that are easily confused with other lesions, possibly left by invertebrate grazers. These findings are likely to be applicable to other straplike seagrass species, though a similar comparison is recommended in the initial stages of a study.
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Cladistic analyses of morphological data were used to clarify the definition of Billardiera in the context of other genera of the family Pittosporaceae. These analyses indicate that Billardiera s.str. is monophyletic including the...
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Cladistic analyses of morphological data were used to clarify the definition of Billardiera in the context of other genera of the family Pittosporaceae. These analyses indicate that Billardiera s.str. is monophyletic including the small genera Sollya and Pronaya, but excluding Marianthus and Rhytidosporum, which have been previously included in a broader concept of Billardiera. The re-circumscribed Billardiera is revised, incorporating these changes. Five taxa are reinstated at species level (B. fusiformis, B. mutabilis, B. macrantha, B. speciosa and B. venusta). Three are new combinations (B. fraseri, B. heterophylla, B. drummondii replacing Sollya drummondii) and three new taxa are described for the first time: B. nesophila, B. rubens and B. viridiflora.
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By a News Reporter-Staff News Editor at Network Daily News - Current study
results on networks have been published. According to news reporting originating from Nedlands, Australia,
by NewsRx correspondents, research stated, “C...
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By a News Reporter-Staff News Editor at Network Daily News - Current study
results on networks have been published. According to news reporting originating from Nedlands, Australia,
by NewsRx correspondents, research stated, “Compression networks are the result of a recently proposed
method to transform univariate time series to a complex network representation by using a compression
algorithm.”
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By a News Reporter-Staff News Editor at Robotics & Machine Learning Daily
News Daily News – New research on Robotics is the subject of a report. According to news reporting
originating in Adelaide, Australia, by NewsRx journalists, research stated, “This study explores the utility of
optical flow calculated from thermal imaging cameras, ‘thermal flow,’ mounted on an aircraft for localization
in day and night conditions. Our sensor implementation utilizes a long wave infrared (LWIR) micro sensor
to capture sequences of thermal images and an on-board computer to compute an optical flow estimate.”...
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By a News Reporter-Staff News Editor at Robotics & Machine Learning Daily
News Daily News – New research on Robotics is the subject of a report. According to news reporting
originating in Adelaide, Australia, by NewsRx journalists, research stated, “This study explores the utility of
optical flow calculated from thermal imaging cameras, ‘thermal flow,’ mounted on an aircraft for localization
in day and night conditions. Our sensor implementation utilizes a long wave infrared (LWIR) micro sensor
to capture sequences of thermal images and an on-board computer to compute an optical flow estimate.”
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