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1
Edwards, G. C., e D. A. Howard. "Air-surface exchange measurements of gaseous elemental mercury over naturally enriched and background terrestrial landscapes in Australia". Atmospheric Chemistry and Physics 13, n.º 10 (27 de maio de 2013): 5325–36. http://dx.doi.org/10.5194/acp-13-5325-2013.
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Abstract. This paper presents the first gaseous elemental mercury (GEM) air-surface exchange measurements obtained over naturally enriched and background (<0.1 μg g−1 Hg) terrestrial landscapes in Australia. Two pilot field studies were carried out during the Australian autumn and winter periods at a copper-gold-cobalt-arsenic-mercury mineral field near Pulganbar, NSW. GEM fluxes using a dynamic flux chamber approach were measured, along with controlling environmental parameters over three naturally enriched and three background substrates. The enriched sites results showed net emission to the atmosphere and a strong correlation between flux and substrate Hg concentration, with average fluxes ranging from 14 ± 1 ng m−2 h−1 to 113 ± 6 ng m−2 h−1. Measurements at background sites showed both emission and deposition. The average Hg flux from all background sites showed an overall net emission of 0.36 ± 0.06 ng m−2 h−1. Fluxes show strong relationships with temperature, radiation, and substrate parameters. A compensation point of 2.48, representative of bare soils was determined. For periods of deposition, dry deposition velocities ranged from 0.00025 cm s−1 to 0.0083 cm s−1 with an average of 0.0041 ± 0.00018 cm s−1, representing bare soil, nighttime conditions. Comparison of the Australian data to North American data suggests the need for Australian-specific mercury air-surface exchange data representative of Australia's unique climatic conditions, vegetation types, land use patterns and soils.
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Hewitt, Mark. "The Vegetation of the Australian Tropical Savannas". Pacific Conservation Biology 8, n.º 3 (2002): 217. http://dx.doi.org/10.1071/pc020217.
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THE publication is a CD containing 1:2 000 000 scale maps in three sheets and an accompanying technical report produced by members of the Queensland Herbarium. It is the result of a collaboration of State, Territory and Federal agencies and researchers. The full list of authors include Fox, I. D., Neldner, V. J., Wilson, G. W., Bannink, P. J., Wilson, B. A., Brocklehurst, P. S., Clark, M. J., Dickinson, K. J. M., Beard, P. S., Hopkins, A. J. M., Beeston, G. R., Harvey, J. M., Thompson, E. J., Ryan, T. S., Thompson, S. L., Butler, S. w., Cartan, H., Addicott, E. P., Bailey, L. P., Cumming, R. J., Johnson, S. C., Schmeider, M., Stephens, K. M. and Bean, A. R.
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Monamy, Vaughan, e Barry J. Fox. "Differential habitat use by a local population of subadult common dunnarts, Sminthopsis murina, following wildfire in coastal wet heath, New South Wales, Australia". Wildlife Research 32, n.º 7 (2005): 617. http://dx.doi.org/10.1071/wr04105.
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Little has been published about Sminthopsis murina, a small insectivorous marsupial encountered infrequently during trapping studies. Individuals favour vegetation associations found in recently burnt heathlands and forests; however, individuals rarely remain in such areas long enough for repeated capture. We report an unusual occurrence of habitat fidelity by a dense population of subadult S. murina in coastal wet heath, New South Wales, Australia. Individuals were captured repeatedly in the first 16 months following wildfire (30 subadults trapped 154 times: recapture rate = 80%). Densities peaked 10 months after fire at 3.75 individuals ha–1. More males than females were captured (23 males, 7 females). Habitat analyses revealed differential use of regenerating coastal wet heathland by S. murina. Significantly more captures were made in areas of high soil moisture in the first six months following fire. Captures then decreased in these areas but increased where soil moisture had been lower and where vegetation had been growing more slowly. Beyond the 1995/96 breeding season, regenerating vegetation became increasingly dense and less patchy and captures of S. murina ultimately declined to zero. This paper records a rare opportunity to examine habitat preferences of a single cohort of subadult S. murina. Habitat use may have been determined by the presence of a narrow range of vegetation structure.
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Huurdeman, E. P., J. Frieling, T. Reichgelt, P. K. Bijl, S. M. Bohaty, G. R. Holdgate, S. J. Gallagher, F. Peterse, D. R. Greenwood e J. Pross. "Rapid expansion of meso-megathermal rain forests into the southern high latitudes at the onset of the Paleocene-Eocene Thermal Maximum". Geology 49, n.º 1 (25 de agosto de 2020): 40–44. http://dx.doi.org/10.1130/g47343.1.
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Abstract Current knowledge of terrestrial ecosystem response to the Paleocene-Eocene Thermal Maximum (PETM; ca. 56 Ma) is largely based on the midlatitudes of the Northern Hemisphere. To more fully reconstruct global terrestrial ecosystem response to the PETM, we generated vegetation and biomarker proxy records from an outcrop section on the southern coast of Australia (∼60°S paleolatitude). We documented a rapid, massive, and sustained vegetation turnover as a response to regional PETM warming of ∼1–4 °C, abruptly transitioning from a warm temperate to a meso-megathermal rain forest similar to that of present-day northeastern Queensland, Australia. The onset of this vegetation change preceded the characteristic PETM carbon-isotope excursion (CIE) by several thousand years. The reconstructed ecosystem change is much stronger than in other Southern Hemisphere records, highlighting the need for consideration of regional paleoceanographic, paleogeographic, and biogeographic characteristics to fully understand the global terrestrial ecosystem response to PETM climate forcing.
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Berry, Sandra L., e Michael L. Roderick. "CO2 and land-use effects on Australian vegetation over the last two centuries". Australian Journal of Botany 50, n.º 4 (2002): 511. http://dx.doi.org/10.1071/bt01019.
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Coincident with major changes in land use and management in Australia over the past 200 years, there has been a 20% increase in the concentration of carbon dioxide ([CO2]) in the atmosphere. We investigate the way in which these two factors have modified the natural vegetation at the continental scale. We describe landscapes in terms of the abundance of three leaf functional types, 'turgor' (T), 'mesic' (M) and 'sclerophyll' (S). We have previously shown that continental-scale estimates of the TMS composition can be made from climatic and satellite data. In this study, we extend those results by estimating the TMS composition for the 'natural' vegetation (i.e. the present vegetation if there had been no change in land use and management). By comparing those estimates with the existing vegetation, we show that changes in land use have resulted in a large increase in the abundance of T leaves (seasonally green leaves of annual and ephemeral herbaceous plants) and there is a corresponding decline in plants with M and S leaves (evergreen trees, shrubs and perennial grasses). We then use a water use efficiency model to estimate the natural vegetation cover 200 years ago when the [CO2] was about 280 μmol mol–1. According to the model, 200 years ago the seasonally green (T) vegetation cover was similar to that at the present (excluding cultural vegetation cover), but there was lower evergreen cover. The increase in evergreen cover with increasing [CO2] could have been expressed as an increase in trees, shrubs or grasses having M and S leaf forms, depending on soil moisture and nutrient availability. According to our model, while 'woody vegetation thickening' may have been exacerbated by the increase in [CO2], other changes associated with European settlement are also important.
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Butcher, R., e K. R. Thiele. "An investigation of taxon boundaries in rare and range-restricted Synaphea (Proteaceae: Conosperminae) species from south-west Western Australia". Australian Systematic Botany 27, n.º 2 (2014): 119. http://dx.doi.org/10.1071/sb14015.
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The Swan Coastal Plain of south-west Western Australia has been extensively cleared since European settlement, with the fertile Pinjarra Plain land system preferentially cleared for grazing; what remains of the native vegetation is of high conservation value despite being highly fragmented and often degraded. The following six taxa of Synaphea R.Br. (Proteaceae), with conservation status corresponding to IUCN Red List categories Threatened and Data Deficient, are restricted to vegetation remnants in this region: S. stenoloba A.S.George, S. odocoileops A.S.George, S. sp. Pinjarra (R. Davis 6578), S. sp. Fairbridge Farm (D. Papenfus 696), S. sp. Pinjarra Plain (A.S. George 17182) and S. sp. Serpentine (G.R. Brand 103). Taxonomic boundaries among these morphologically similar taxa of Synaphea were investigated using morphometric analyses based on characters of leaves, inflorescences, flowers and fruits. Results allow the circumscription of the four informally named taxa from this complex, which will enable their formal description in a subsequent publication. They also provide support for several morphologically closely related taxa, including the provisional distinction of S. sp. Udumung (A.S. George 17058) from close ally S. decorticans Lindl. Two described species (S. odocoileops and S. stenoloba) and several anomalous specimens could not be adequately resolved in these analyses, and further investigation of their boundaries using molecular markers is required.
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Howell, Jocelyn, Doug Benson e Lyn McDougall. "Developing a strategy for rehabilitating riparian vegetation of the Hawkesbury-Nepean River, Sydney, Australia". Pacific Conservation Biology 1, n.º 3 (1994): 257. http://dx.doi.org/10.1071/pc940257.
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Situated on the southeastern coast at 34�S 151�E, Sydney was established in 1788 as Australia's first permanent European settlement. Clearing of natural vegetation and environmental degradation associated with the country's largest population concentration over the past 200 years have severely affected the nearby Hawkesbury-Nepean River. A strategy for rehabilitation of the riparian vegetation to conserve and enhance the natural conditions remaining along the river, with particular emphasis on habitat and natural biodiversity, has been developed. The study area encompassed the most modified part of the river, where it passes alternately through 80 km of sandstone terrain, where the natural vegetation of waterside scrub backed by open-forest remains largely unchanged, and 135 km of floodplain terrain, where most of the indigenous tall open-forest has been cleared and associated wetlands have been greatly modified. Indigenous riparian zone vegetation was recognized as critical to the maintenance of river health, providing a reservoir of biodiversity as a major value, upon which other values, including enhancement of water quality, bank stablility and erosion control, depend. As 47 per cent of study area riverbank was found to have less than 25 per cent tree cover, the strategy recommended that all remnant native vegetation and remnant native trees along the river be protected and that a substantial long-term aim should be the establishment of a 50-metre wide strip of native riparian forest vegetation on each bank along the full length of the river, to be linked ultimately with other areas of natural vegetation on the floodplain. To provide practical resources for revegetation, the strategy assembled a botanical database, including maps showing present tree cover and the past extent of floodplain vegetation types, descriptions and locations of sites where significant native riparian vegetation remains, ecological information on approximately 300 locally indigenous riparian and wetland plant species, guidelines on selection of appropriate species, replanting methods and determination of priorities at both site and landscape scale.
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Broich, M., e M. G. Tulbure. "RESPONSE OF RIPARIAN VEGETATION IN AUSTRALIA"S LARGEST RIVER BASIN TO INTER AND INTRA-ANNUAL CLIMATE VARIABILITY AND FLOODING AS QUANTIFIED WITH LANDSAT AND MODIS". ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLI-B8 (23 de junho de 2016): 577–78. http://dx.doi.org/10.5194/isprs-archives-xli-b8-577-2016.
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Australia is a continent subject to high rainfall variability, which has major influences on runoff and vegetation dynamics. However, the resulting spatial-temporal pattern of flooding and its influence on riparian vegetation has not been quantified in a spatially explicit way. Here we focused on the floodplains of the entire Murray-Darling Basin (MDB), an area that covers over 1M km<sup>2</sup>, as a case study. The MDB is the country’s primary agricultural area with scarce water resources subject to competing demands and impacted by climate change and more recently by the Millennium Drought (1999–2009). Riparian vegetation in the MDB floodplain suffered extensive decline providing a dramatic degradation of riparian vegetation. <br><br> We quantified the spatial-temporal impact of rainfall, temperature and flooding patters on vegetation dynamics at the subcontinental to local scales and across inter to intra-annual time scales based on three decades of Landsat (25k images), Bureau of Meteorology data and one decade of MODIS data. <br><br> Vegetation response varied in space and time and with vegetation types, densities and location relative to areas frequently flooded. Vegetation degradation trends were observed over riparian forests and woodlands in areas where flooding regimes have changed to less frequent and smaller inundation extents. Conversely, herbaceous vegetation phenology followed primarily a ‘boom’ and ‘bust’ cycle, related to inter-annual rainfall variability. Spatial patters of vegetation degradation changed along the N-S rainfall gradient but flooding regimes and vegetation degradation patterns also varied at finer scale, highlighting the importance of a spatially explicit, internally consistent analysis and setting the stage for investigating further cross-scale relationships. <br><br> Results are of interest for land and water management decisions. The approach developed here can be applied to other areas globally such as the Nile river basin and Okavango River delta in Africa or the Mekong River Basin in Southeast Asia.
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Los, S. O., J. A. B. Rosette, N. Kljun, P. R. J. North, J. C. Suárez, C. Hopkinson, R. A. Hill et al. "Vegetation height products between 60° S and 60° N from ICESat GLAS data". Geoscientific Model Development Discussions 4, n.º 3 (19 de setembro de 2011): 2327–63. http://dx.doi.org/10.5194/gmdd-4-2327-2011.
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Abstract. We present a new method to obtain coarse resolution (0.5° × 0.5°) vegetation height and vegetation-cover fraction data sets between 60° S and 60° N for use in climate models and ecological models. The data sets are derived from the Geoscience Laser Altimeter System (GLAS) on the Ice, Cloud and land Elevation Satellite (ICESat), which is the only LiDAR instrument that provides close to global coverage when all data collected for 2003–2009 are combined. Filters are applied to the GLAS data to identify and eliminate spurious observations, e.g. data that are affected by clouds, atmosphere and terrain and as such result in erroneous estimates of vegetation height or vegetation cover. GLAS vegetation height estimates are aggregated in histograms from 0 to 70 m in 0.5 m intervals. The GLAS vegetation height product is evaluated in four ways. First, unfiltered and filtered individual GLAS vegetation height measurements are compared with aircraft LiDAR measurements of the same from seven sites in the Americas, Europe, and Australia. Application of filters increases the correlation with aircraft data from r = 0.36 to r = 0.67 and decreases the root-mean-square error by a factor 3. Second, the global aggregated GLAS vegetation height product is tested for sensitivity towards the choice of data quality filters; areas with frequent cloud cover and areas with steep terrain are the most sensitive to the choice of thresholds for the filters. Thirdly, the GLAS global vegetation height product is compared with two other global vegetation height products and is believed to produce more realistic characteristics: dominant vegetation height for tropical forests between 30 and 60 m versus 20 and 40 m in existing products. Finally, the GLAS bare soil cover fraction is compared globally with the MODIS bare soil fraction (r = 0.55) and with the FASIR bare soil cover fraction estimates (r = 0.58); the correlation between GLAS and MODIS tree-cover fraction was (r = 0.76). The evaluation indicates that filters applied to the GLAS data are conservative and eliminate a large proportion of spurious data, while only in a minority of cases at the cost of removing reliable data as well. The present GLAS vegetation height product appears more realistic than previous data sets used for input to climate models and ecological models and hence should significantly improve simulations that involve the land surface.
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Broich, M., e M. G. Tulbure. "RESPONSE OF RIPARIAN VEGETATION IN AUSTRALIA"S LARGEST RIVER BASIN TO INTER AND INTRA-ANNUAL CLIMATE VARIABILITY AND FLOODING AS QUANTIFIED WITH LANDSAT AND MODIS". ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLI-B8 (23 de junho de 2016): 577–78. http://dx.doi.org/10.5194/isprsarchives-xli-b8-577-2016.
Texto completo da fonteResumo:
Australia is a continent subject to high rainfall variability, which has major influences on runoff and vegetation dynamics. However, the resulting spatial-temporal pattern of flooding and its influence on riparian vegetation has not been quantified in a spatially explicit way. Here we focused on the floodplains of the entire Murray-Darling Basin (MDB), an area that covers over 1M km<sup>2</sup>, as a case study. The MDB is the country’s primary agricultural area with scarce water resources subject to competing demands and impacted by climate change and more recently by the Millennium Drought (1999–2009). Riparian vegetation in the MDB floodplain suffered extensive decline providing a dramatic degradation of riparian vegetation. <br><br> We quantified the spatial-temporal impact of rainfall, temperature and flooding patters on vegetation dynamics at the subcontinental to local scales and across inter to intra-annual time scales based on three decades of Landsat (25k images), Bureau of Meteorology data and one decade of MODIS data. <br><br> Vegetation response varied in space and time and with vegetation types, densities and location relative to areas frequently flooded. Vegetation degradation trends were observed over riparian forests and woodlands in areas where flooding regimes have changed to less frequent and smaller inundation extents. Conversely, herbaceous vegetation phenology followed primarily a ‘boom’ and ‘bust’ cycle, related to inter-annual rainfall variability. Spatial patters of vegetation degradation changed along the N-S rainfall gradient but flooding regimes and vegetation degradation patterns also varied at finer scale, highlighting the importance of a spatially explicit, internally consistent analysis and setting the stage for investigating further cross-scale relationships. <br><br> Results are of interest for land and water management decisions. The approach developed here can be applied to other areas globally such as the Nile river basin and Okavango River delta in Africa or the Mekong River Basin in Southeast Asia.
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Bowman, DMJS. "Diversity Patterns of Woody Species on a Latitudinal Transect From the Monsoon Tropics to Desert in the Northern Territory, Australia". Australian Journal of Botany 44, n.º 5 (1996): 571. http://dx.doi.org/10.1071/bt9960571.
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A belt transect, made up of 15 contiguous cells (width, 3.5° of longitude; length, 1° of latitude), was established from the monsoon tropics on the central north coast of the Northern Temtory (11°S) to the central Australian desert on the South Australian border (26°S). On this transect, mean annual rainfall was found to have a negative exponential decay with latitude, with arid conditions commencing at around 18"s-the limit of the monsoonal rains. The mean elevation of each cell steadily increased from the north coast to reach a maximum average elevation of 700 m at around 23°S. The mean alphadiversity (quadrat species richness), and mean beta-diversity (turnover of species along an environmental gradient) was determined for each of the 15 cells by sub-sampling a large 20 × 20 m quadrat data set (N > 2000) collected during the course of the Northern Territory 1:106 vegetation mapping program. It was found that there was little within-cell variation of beta-diversity of woody species which occurred in at least five quadrats, as approximated by the first axis of a detrended correspondence analysis (DCA) of these data. The mean first axis DCA scores were strongly correlated with latitude (r = 0.99); thus, there is no evidence for a floristic disjunction in the composition of common woody species between the monsoon tropics and desert. Mean alpha-diversity had a bimodal distribution on the latitudinal transect, with the maximum mean quadrat richness in the monsoon tropics and a second smaller peak occurred in central Australia, with the lowest levels of alpha-diversity to the south of the limit of the monsoon rains. This pattern was mirrored by the mean number and mean Shannon-Wiener diversity of 1:106 vegetation map units on the transect. It was found that 81% of the variance of mean alpha-diversity was explained by mean annual rainfall and mean elevation for the 15 cells. The increase in mean alpha-diversity in central Australia appears to be related to environmental heterogeneity associated with mountainous terrain. It is possible that the central Australian mountains are a refuge for plants that were more widespread during the last ice-age. It is unknown whether the woody species diversity patterns are in equilibrium with the prevailing climate. More data on the palaeo-environments of the Northern Territory are required to answer this question.
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Los, S. O., J. A. B. Rosette, N. Kljun, P. R. J. North, L. Chasmer, J. C. Suárez, C. Hopkinson et al. "Vegetation height and cover fraction between 60° S and 60° N from ICESat GLAS data". Geoscientific Model Development 5, n.º 2 (27 de março de 2012): 413–32. http://dx.doi.org/10.5194/gmd-5-413-2012.
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Abstract. We present new coarse resolution (0.5° × 0.5°) vegetation height and vegetation-cover fraction data sets between 60° S and 60° N for use in climate models and ecological models. The data sets are derived from 2003–2009 measurements collected by the Geoscience Laser Altimeter System (GLAS) on the Ice, Cloud and land Elevation Satellite (ICESat), the only LiDAR instrument that provides close to global coverage. Initial vegetation height is calculated from GLAS data using a development of the model of Rosette et al. (2008) with with further calibration on desert sites. Filters are developed to identify and eliminate spurious observations in the GLAS data, e.g. data that are affected by clouds, atmosphere and terrain and as such result in erroneous estimates of vegetation height or vegetation cover. Filtered GLAS vegetation height estimates are aggregated in histograms from 0 to 70 m in 0.5 m intervals for each 0.5° × 0.5°. The GLAS vegetation height product is evaluated in four ways. Firstly, the Vegetation height data and data filters are evaluated using aircraft LiDAR measurements of the same for ten sites in the Americas, Europe, and Australia. Application of filters to the GLAS vegetation height estimates increases the correlation with aircraft data from r = 0.33 to r = 0.78, decreases the root-mean-square error by a factor 3 to about 6 m (RMSE) or 4.5 m (68% error distribution) and decreases the bias from 5.7 m to −1.3 m. Secondly, the global aggregated GLAS vegetation height product is tested for sensitivity towards the choice of data quality filters; areas with frequent cloud cover and areas with steep terrain are the most sensitive to the choice of thresholds for the filters. The changes in height estimates by applying different filters are, for the main part, smaller than the overall uncertainty of 4.5–6 m established from the site measurements. Thirdly, the GLAS global vegetation height product is compared with a global vegetation height product typically used in a climate model, a recent global tree height product, and a vegetation greenness product and is shown to produce realistic estimates of vegetation height. Finally, the GLAS bare soil cover fraction is compared globally with the MODIS bare soil fraction (r = 0.65) and with bare soil cover fraction estimates derived from AVHRR NDVI data (r = 0.67); the GLAS tree-cover fraction is compared with the MODIS tree-cover fraction (r = 0.79). The evaluation indicates that filters applied to the GLAS data are conservative and eliminate a large proportion of spurious data, while only in a minority of cases at the cost of removing reliable data as well. The new GLAS vegetation height product appears more realistic than previous data sets used in climate models and ecological models and hence should significantly improve simulations that involve the land surface.
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Sinclair, Russell. "Long-term changes in vegetation, gradual and episodic, on the TGB Osborn Vegetation Reserve, Koonamore, South Australia (1926 - 2002)". Australian Journal of Botany 53, n.º 4 (2005): 283. http://dx.doi.org/10.1071/bt04144.
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The TGB Osborn Vegetation Reserve at Koonamore, South Australia, is a 390-ha exclosure in semi-arid chenopod shrubland. The area was heavily overgrazed in 1925 when it was fenced to exclude sheep. Permanent quadrats and photopoints have been maintained to the present. Feral rabbits were sometimes numerous until the mid-1970s but have since been controlled. The records represent 50 years without sheep grazing, followed by 26 years without either sheep or rabbits. Dramatic seedling establishment events have occurred since 1978 for the following species: Acacia aneura Benth., Myoporum platycarpum R.Br., Senna artemesioides subsp. coriacea Randell, S. artemesioides subsp. petiolaris Randell, Acacia burkittii Benth., Dodonaea attenuata A.Cunn., Eremophila longifolia (R.Br.) F.Muell., E. sturtii R.Br. and Maireana pyramidata (Benth.) Paul G.Wilson. However, the chenopod shrubs Atriplex vesicaria Benth. and A. stipitata Benth. increased earlier and did not respond in the same way to episodic rainfall events or rabbit control. Numbers of Alectryon oleifolius (Desf.) S.T.Reynolds and Casuarina pauper F.Muell. ex L.A.S.Johnson have remained almost unchanged, whereas Maireana sedifolia (F.Muell.) Paul G.Wilson and M. astrotricha (L.Johnson) Paul G.Wilson have shown a very gradual increase over time. The data show evidence for both episodic and gradual change among different species.
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Keast, Allen. "History of the Australian Vegetation: Cretaceous to Recent.Robert S. Hill". Quarterly Review of Biology 70, n.º 4 (dezembro de 1995): 503–4. http://dx.doi.org/10.1086/419187.
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Martin, A. R. H. "Pollen Analysis of Digger's Creek Bog, Kosciuszko National Park: Vegetation History and Tree-line Change". Australian Journal of Botany 47, n.º 5 (1999): 725. http://dx.doi.org/10.1071/bt98002.
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Digger's Creek Bog, an Empodisma minus–Callistemon pityoides–Sphagnum cristatum shrubby subalpine peat bog, alt. c. 1690 m, not far below local altitudinal tree-line, began development > 10 000 years before present as an Astelia sp.–Carex alpine soak. Surrounding vegetation was a grassy alpine herbfield with many Asteraceae, Apiaceae and Gentianella diemensis, corresponding to the regional Club Lake Zone C, dated to the same period. Astelia died out c. 6500 years before present approximately at the Club Lake C/D 1 boundary, marked by spread of Pomaderris in subjacent montane forests. Thereafter, shrubs, mainly Myrtaceae and Epacridaceae, and Restionaceae (Empodisma and Restio australis) dominated the bog. Epacris cf. paludosa and C. pityoides seem to have been the earliest shrubs to invade, Baeckea, probably B. gunniana, and Richea continentis reaching maximum prominence 5000–3000 years before present. Sphagnum was uncommon until recently. Regional arboreal pollen enable comparisons with other sites in south-eastern Australia but immigration of the tree-line species Eucalyptus pauciflora subsp. niphophila (snowgum) is not well expressed in the pollen spectra. Surface and near-surface counts of this species are higher than at any preceding time, and correspond most closely to surface counts in adjacent young snowgum woodland. The co-occurrence of weed pollens, probably associated with the late 19th and early 20th century practice of summer pasturing stock on the alpine–subalpine tract, suggests that pasturing and burning, responsible for widespread severe fires on this range, led both to the formation of dense even-aged snowgum woodland that had been open and patchy at this altitude, and a spread of Sphagnum on the bog surface.
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Kennedy, Shaun A., George G. Ganf e Keith F. Walker. "Does salinity influence the distribution of exotic willows (Salix spp.) along the Lower River Murray?" Marine and Freshwater Research 54, n.º 7 (2003): 825. http://dx.doi.org/10.1071/mf03035.
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The weeping willow Salix babylonica and crack willow S. fragilis dominate the riparian vegetation of the River Murray between Mannum and Wellington, South Australia, Australia. The presence of S. fragilis is confirmed, over-riding earlier, informal references to S. × rubens. In this region S. babylonica is represented by females and S. fragilis is represented by males. The flowering times of the two species overlap but the growing season begins earlier for the former. No evidence of hybridization was found, although this is not conclusive. Salix babylonica is most common upstream of Murray Bridge whereas S. fragilis occurs mainly downstream. A field survey in 1999 showed that estimated soil water conductivity varied between sites (median 6.0 mS cm–1) along the river, but this was not reflected in the distributions of the species. In a glasshouse experiment, cuttings of both species proved intolerant of conductivities exceeding 7 mS cm–1. In the field, foliar salt levels indicated that neither species was salt-stressed, despite growing in moderately saline soil. Also, it appears that the trees may access less saline river water in preference to that in the soil. The distributions of the two species in this region could reflect the history of planting rather than salinity tolerance.
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Bullen, R. D., e J. N. Dunlop. "Assessment of habitat usage by bats in the rangelands of Western Australia: comparison of echolocation call count and stable isotope analysis methods". Rangeland Journal 34, n.º 3 (2012): 277. http://dx.doi.org/10.1071/rj12001.
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The activity levels of seven species of insectivorous microbats in five habitats widespread across the Charles Darwin Reserve in the Murchison region of Western Australia were measured using echolocation detectors and compared with results of habitat usage revealed by stable isotope analysis. The activity levels were further compared with projective foliage density as a surrogate of productivity within each habitat. Habitat use, estimated from echolocation activity of the microbat species and from stable isotope analysis of their fur, agree and each provides complementary information on the habitats preferred by species. Both methods show that five of the species, Chalinolobus gouldii, C. morio, Mormopterus species 3, Nyctophilus geoffroyi and Tadarida australis, are active and forage over each of the five habitats. Scotorepens balstoni is shown by both methods to prefer habitats with C3 woodland over C4 shrubs and grasses. Vespadelus baverstocki is shown by both methods to fly and forage over habitats with developed arid-zone shrubland understorey vegetation. The echolocation method shows that bat activity levels align with the foliage mass of the vegetation as measured by the projected foliage density. The species’ stable isotope signatures show that the insects captured are feeding primarily on the ground cover of the habitats. The two species that have high δC signatures, S. balstoni and V. baverstocki, are shown to be most active in habitats with a C4 ground cover.
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COLLOFF, MATTHEW J. "Comparative morphology and species-groups of the oribatid mite genus Scapheremaeus (Acari: Oribatida: Cymbaeremaeidae), with new species from South Australia". Zootaxa 2213, n.º 1 (28 de agosto de 2009): 1–46. http://dx.doi.org/10.11646/zootaxa.2213.1.1.
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The morphology of the genus Scapheremaeus Berlese, 1910 is reviewed and characters of taxonomic utility delineated. Based on the morphological review, some 13 species-groups are outlined based on major morphotypes. There are two main categories: i) species that have a complete circumdorsal scissure with plicate microsculpture on the circumnotogastral plate and strongly contrasting microsculpture (foveolae, ridges or tubercles) on the centrodorsal plate (plicate species-groups), and ii) species with the circumdorsal scissure complete, incomplete or absent but with little or no contrast in microsculpture between the central and lateral regions: typically both regions foveolate or reticulate (non- plicate species-groups). A catalogue of world species of Scapheremaeus is provided. Scapheremaeus petrophagus (Banks, 1906) is not a Scapheremaeus but belongs to an undetermined genus in the Ameronothroidea. Cymbaeremaeus cyclops Oudemans, 1915 is recombined to Scapheremaeus. Five new species are described (S. angusi sp. nov., S. cheloniella sp. nov., S. ewani sp. nov., S. lambieae sp. nov., and S. pulleni sp. nov.) from soil and litter habitats in semi-arid Mallee eucalypt vegetation at Bookmark Biosphere Reserve, South Australia. These are the first members of the genus Scapheremaeus to be described from Australia, though undescribed species have been recorded previously. All the new species are morphologically closely-related and belong to a single species-group: Carinatus.
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Edney, P. A., A. P. Kershaw e P. De Deckker. "A late pleistocene and holocene vegetation and environmental record from Lake Wangoom, Western Plains of Victoria, Australia". Palaeogeography, Palaeoclimatology, Palaeoecology 80, n.º 3-4 (novembro de 1990): 325–43. http://dx.doi.org/10.1016/0031-0182(90)90141-s.
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de Salas, Miguel F., Matthew L. Baker, Lynette Cave e Gintaras Kantvilas. "The botany of the Stony Head Training Area: new records for a biodiverse remnant in northern Tasmania, Australia". Proceedings of the Royal Society of Victoria 134, n.º 2 (14 de fevereiro de 2023): 85–107. http://dx.doi.org/10.1071/rs22003.
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A flora survey of the Stony Head Training Area, northern Tasmania, was conducted in 2020–2021 as a collaboration between the Tasmanian Museum and Art Gallery’s Expeditions of Discovery and the Australian Biological Resources Study Bush Blitz programs. With a long historical use as an artillery range, the 5000-ha area contains a range of geologies, has a low profile with average elevations under 100 m asl, and its vegetation consists largely of heathy woodlands and coastal heathlands. It contains a range of relatively undisturbed, high-quality native habitats and populations of several threatened species. The survey targeted vascular plants, bryophytes and lichens, and recorded a total of 575 taxa. Nine lichens are new records for Tasmania — <i>Buellia hypostictella</i>, <i>Caloplaca gilfillaniorum</i>, <i>Cladonia subradiata</i>, <i>Graphis geraensis</i>, <i>Lecanora intumescens</i> and <i>Opegrapha diaphoriza</i> — all previously also known from mainland Australia, and <i>Micarea rhabdogena</i>, <i>M. xanthonica</i> and <i>Pseudothelomma ocellatum</i>, which represent first records for the Southern Hemisphere. Biogeographical and ecological patterns in the flora, the contribution of vegetation remnants to flora conservation, and the ongoing importance of surveys and alpha-taxonomy for documenting biodiversity are discussed. Our findings are consistent with a body of research showing a trend of healthy populations of threatened taxa within military training areas.
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Davis, JA, SA Harrington e JA Friend. "Invetebrate communities of Relict streams in the Arid Zone: the George Gill Range, Central Australia". Marine and Freshwater Research 44, n.º 3 (1993): 483. http://dx.doi.org/10.1071/mf9930483.
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The George Gill Range (24�S,132�E) 220 km south west of Alice Springs in the Northern Territory, lies within one of the driest regions of Australia. Diel and seasonal temperature differences are extreme and the average rainfall is 250 mm per annum. The streams of the Range are the largest group within the Central Ranges and are relatively pristine. Their flow regimes are episodic but deep rock pools appear to act as reservoirs of surface runoff and may also receive groundwater from the Mereenie aquifer. The waterbodies of the Range and some nearby areas were sampled in July and December 1986 to determine the composition of the macroinvertebrate communities and biogeographical relationships with the fauna of lotic systems elsewhere in Australia. Macroinvertebrate species richness at the Range was comparable with that of other Australian streams but no Plecoptera, Isopoda or Amphipoda were collected. The almost complete absence of shredders may reflect low allochthonous inputs, because riparian vegetation in the arid zone is generally sparse. A small proportion of the fauna of the Range appears to be a relictual stream fauna. Species of low vagility such as the waterpenny, Sclerocyphon fuscus, would not be capable of dispersal across the large tracts of arid land that now separate the Range from southern Australia, where it is also found. The occurrence of new species at the Range suggests that it is also a site of allopatric speciation within some groups. The conservation values of the streams of the George Gill Range and other sites, such as Giles Springs in the Chewings Range, are extremely high. They represent unique aquatic communities of both ecological and evolutionary importance in the arid zone.
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Clarke, Michael F., Sarah C. Avitabile, Lauren Brown, Kate E. Callister, Angie Haslem, Greg J. Holland, Luke T. Kelly et al. "Ageing mallee eucalypt vegetation after fire: insights for successional trajectories in semi-arid mallee ecosystems". Australian Journal of Botany 58, n.º 5 (2010): 363. http://dx.doi.org/10.1071/bt10051.
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A critical requirement in the ecological management of fire is knowledge of the age-class distribution of the vegetation. Such knowledge is important because it underpins the distribution of ecological features important to plants and animals including retreat sites, food sources and foraging microhabitats. However, in many regions, knowledge of the age-class distribution of vegetation is severely constrained by the limited data available on fire history. Much fire-history mapping is restricted to post-1972 fires, following satellite imagery becoming widely available. To investigate fire history in the semi-arid Murray Mallee region in southern Australia, we developed regression models for six species of mallee eucalypt (Eucalyptus oleosa F.Muell. ex. Miq. subsp. oleosa, E. leptophylla F.Muell. ex. Miq., E. dumosa J. Oxley, E. costata subsp. murrayana L. A. S. Johnson & K. D. Hill, E. gracilis F.Muell. and E. socialis F.Muell. ex. Miq.) to quantify the relationship between mean stem diameter and stem age (indicated by fire-year) at sites of known time since fire. We then used these models to predict mean stem age, and thus infer fire-year, for sites where the time since fire was not known. Validation of the models with independent data revealed a highly significant correlation between the actual and predicted time since fire (r = 0.71, P < 0.001, n = 88), confirming the utility of this method for ageing stands of mallee eucalypt vegetation. Validation data suggest the models provide a conservative estimate of the age of a site (i.e. they may under-estimate the minimum age of sites >35 years since fire). Nevertheless, this approach enables examination of post-fire chronosequences in semi-arid mallee ecosystems to be extended from 35 years post-fire to over 100 years. The predicted ages identified for mallee stands imply a need for redefining what is meant by ‘old-growth’ mallee, and challenges current perceptions of an over-abundance of ‘long-unburnt’ mallee vegetation. Given the strong influence of fire on semi-arid mallee vegetation, this approach offers the potential for a better understanding of long-term successional dynamics and the status of biota in an ecosystem that encompasses more than 250 000 km2 of southern Australia.
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Coupland, Grey T., Eric I. Paling e Keith A. McGuinness. "Vegetative and reproductive phenologies of four mangrove species from northern Australia". Australian Journal of Botany 53, n.º 2 (2005): 109. http://dx.doi.org/10.1071/bt04066.
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Mangrove communities in the tropical north of Australia are some of the most species rich in the world, yet surprisingly little is known of their reproductive and vegetative phenology. This study investigated the phenology of four mangrove species: Avicennia marina (Forsk.) Vierh., Ceriops australis (C.T.White) Ballment, T.J.Sm & Stoddart, Rhizophora stylosa Griff. and Sonneratia alba J.Smith, in Darwin Harbour over 24 months. Investigations included documenting the flowering and fruiting phenology, periods of leaf flush and leaf longevity. Flowering in these mangroves generally occurred during the dry season (June–October), with the exception of R. stylosa in which flowering occurred in the middle of the wet (December–February). Fruits and propagules were released in the dry and ‘build up’ periods (August–November), with the exception of A. marina, which released propagules in the middle of the wet season. Fruit and/or propagule maturation took less than 2 months in A. marina and S. alba, whereas in C. australis and R. stylosa maturation took 12 and 11 months, respectively. Timing of new leaf production generally coincided with the wet season, after the flowering and fruiting periods of each of the four species. Periods of leaf flush and leaf fall were often closely linked, and species with longer-lived leaves produced fewer leaves at each period of leaf flush. Maximum leaf longevity varied considerably among mangroves, ranging from 8 months in the lower canopy of S. alba to more than 24 months in C. australis. There was also large variability in leaf longevity among different regions of the canopy, with shade leaves generally living longer than sun leaves, and leaves in the upper canopy (3–7 m) longer than those in the lower regions (0–3 m).
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Coates, T. D. "The effect of fox control on mammal populations in an outer urban conservation reserve." Australian Mammalogy 30, n.º 2 (2008): 51. http://dx.doi.org/10.1071/am08007.
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European red foxes were systematically removed from a 370 ha conservation reserve on Melbourne?s urban fringe between December 2003 and September 2005. Activity indexes monitored throughout the removal phase indicated that the fox population declined dramatically when poison baits were available and then increased again predictably during winter and summer each subsequent year. Three alternate indices of fox activity were highly synchronous throughout the study suggesting that the bait-removal index used widely in Australia may provide a reliable measure of overall fox activity in small urban reserves. With monitoring and strategic baiting, fox activity was maintained at a fraction of its pre-control level. Activity indices for several other species of mammal also appeared to respond to the reduced density of foxes at the site after 2003. Southern brown bandicoots (Isoodon obesulus) and swamp wallabies (Wallabia bicolor) increased in both activity and range after the reduction in the fox population indicating that fox predation may act to limit both the total size of populations and types of vegetation occupied by indigenous mammals in small patches of remnant vegetation.
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Basinger, J. F., D. R. Greenwood, P. G. Wilson e D. C. Christophel. "Fossil flowers and fruits of capsular Myrtaceae from the Eocene of South Australia." Canadian Journal of Botany 85, n.º 2 (janeiro de 2007): 204–15. http://dx.doi.org/10.1139/b07-001.
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Flowers and fruits of the Myrtaceae are described from the Middle Eocene Golden Grove locality of South Australia, and the taxon is here named Tristaniandra alleyi gen. et sp.nov. Flowers are pentamerous and perigynous, with sepals, petals, and stamens inserted on the rim of a hypanthium. Filaments are basally fused to form antepetalous stamen bundles, each consisting of about 6–8 stamens. The tricarpellate ovary becomes exserted on maturation, forming a partly exserted, dry fruit with loculicidal dehiscence. These features are typical of capsular-fruited members of the Myrtaceae; in particular, taxa in the tribe Kanieae. While the characteristics of the fossils are not found within any one extant genus, the fossils show some similarity to living species of Tristaniopsis , although the staminal bundles are more comparable to those found in Tristania , which is only distantly related and has a rather different fruit. Capsular-fruited Myrtaceae are now primarily confined to Australasia, and appear to have had a Gondwanic origin in the latest Cretaceous to Paleogene. Nevertheless, as fossil flowers and fruits are rare, and infrafamilial identification of pollen and leaves is difficult, the Paleogene record of capsular Myrtaceae is largely equivocal. The Golden Grove fossils establish a record of the tribe Kanieae within Eocene coastal rainforest vegetation at paleolatitude 55°–58°S during a time of global warmth.
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Wells, PM, e RS Hill. "Fossil imbricate-leaved Podocarpaceae from tertiary sediments in Tasmania". Australian Systematic Botany 2, n.º 4 (1989): 387. http://dx.doi.org/10.1071/sb9890387.
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Fifteen new species belonging to five genera (one, Mesibovia, newly described) of the Podocarpaceae with imbricate leaves are described from Oligocene–Early Miocene localities in Tasmania. Nine of these species belong to Dacrycarpus, which is now extinct in Australia, and their living affinities are widespread in latitude and altitude from New Zealand to New Guinea. Three species of Dacrydium s. str. demonstrate that this genus was diverse in Tasmania in the Tertiary, although it is now extinct in Australia. A species of Microstrobos, which is very similar to the extant alpine/subalpine Tasmanian endemic M. niphophilus, occurs in both high- and low-altitude sites, and suggests that this type was once more widespread. The Oligocene Lagarostrobos marginata is intermediate between the two extant species of Lagarostrobos, and suggests a closer relationship between them than do other lines of evidence. Mesibovia rhomboideu, recovered from three localities, shares features with several extant genera, and is of importance in understanding evolution within this group. The significance of the fossils for climatic and vegetation reconstruction is discussed.
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Olesen, T., C. M. Menzel, N. Wiltshire e C. A. McConchie. "Flowering and shoot elongation of lychee in eastern Australia". Australian Journal of Agricultural Research 53, n.º 8 (2002): 977. http://dx.doi.org/10.1071/ar01179.
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We investigated the effects of the timing of shoot elongation on the flowering of lychee (Litchi chinensis Sonn.) in eastern Australia. Trees of cv. Kwai May Pink growing in Alstonville (lat. 28.9° S) were pruned during spring and summer, and subsequent shoot elongation was measured until the following spring. New shoots grew by discrete flushes, with the trees initiating 3, 2, or 1 vegetative shoots prior to winter, according to the pruning sequence. Shoots were vegetative when the mean temperature during early flush development was above 17-19°C, and floral at lower temperatures. Trees with successive flushes commencing in February (late summer) and June (early winter) were more likely to flower than trees with flushes commencing in April and August, because the weather conditions in June were cooler than those in August and more likely to favour induction. The importance of cool weather conditions during early flush development for floral determination was not significantly affected by the number of vegetative flushes to develop between pruning and winter. Having shown that the phase of recurrent flushing affects flowering, we sought to model the process in order to recognise reproductive and non-reproductive cycles along Australia's north-eastern seaboard, and to develop a management strategy for the promotion of flowering. From the results of the Alstonville pruning trial, the interval between successive flushes was regressed against the mean product of daily irradiation and mean daily temperature (°C.MJ/[m2.day]) during the interval. The regression was used in conjunction with long-term weather records to estimate the flush commencement dates required for the completion of 1 or 2 vegetative flushes by the winter solstice at different latitudes. The earliest date for the completion of 1 flush ranged from 16 February in northern New South Wales (lat. 30° S) to 13 March in northern Queensland (lat. 17° S). To test the model, a pruning trial was conducted near Mareeba (lat. 17° S). Trees pruned on 10 February, estimated to produce ≈ 1.5 flushes prior to winter (i.e. flushes in late autumn and early spring, but not in winter), flowered poorly and had low yields. In contrast, trees pruned on 11 March, estimated to produce 1 vegetative flush by winter, had good flowering and yields. Thus, strategic pruning after harvest can be used to manipulate flushing times, so that new, potentially flowering shoots emerge in winter. Cool temperatures are still required for successful flowering, and we provide estimates of the likelihood of such weather in the major growing areas by calculating the annual number of days with a mean temperature <20°C. For Cairns (lat. 16.9° S) the number of such days varied from 0 to 39 from 1888 to 1993, which is consistent with the irregular flowering of lychee in coastal northern Queensland. Our work is the first demonstration for any species that the phase of recurrent flushing affects flowering, and emphasises the interplay between a plant's endogenous developmental cycle and seasonal variations in weather.
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Orgill, Susan E., Jason R. Condon, Mark K. Conyers, Stephen G. Morris, Brian W. Murphy e Richard S. B. Greene. "Parent material and climate affect soil organic carbon fractions under pastures in south-eastern Australia". Soil Research 55, n.º 8 (2017): 799. http://dx.doi.org/10.1071/sr16305.
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In the present field survey, 72 sites were sampled to assess the effect of climate (Monaro, Boorowa and Coleambally regions) and parent material (Monaro region only; basalt and granite) on soil organic carbon (OC) under perennial pastures. In the higher-rainfall zone (Monaro and Boorowa; >500mm mean annual rainfall), OC stocks under introduced and native perennial pastures were compared, whereas in the lower-rainfall zone (Coleambally; <500mm mean annual rainfall) OC stocks under crops and pastures were compared. Carbon fractions included total OC (TOC), particulate OC (POC), resistant OC (ROC) and humic OC (HUM). Higher OC stocks were associated with higher spring and summer rainfall and lower annual temperatures. Within a climatic zone, parent material affected the stock of OC fractions in the 0–30cm soil layer. Within a climatic zone, when grouped by parent material, there was no difference in OC stock with vegetation type. There were significant correlations between soil factors associated with parent material and OC concentration, including negative correlations between SiO2 and HUM (P<0.05) and positive correlations between cation exchange capacity and TOC, POC and ROC (P<0.01). TOC was also positively correlated with total nitrogen (N) and available sulfur (S; P<0.05), indicating organic matter in soil is important for N and S supply for plant production in the studied regions, and vice versa. Although ensuring adequate available S may increase OC stocks in south-eastern Australia, the large stock of OC in the soil under perennial pastures, and the dominating effect of climate and parent material on this stock, may mean that modest increases in soil OC due to management factors go undetected.
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T. Kingsford, Richard. "Managing Australia's Scarce Water Resources for the Environment". Pacific Conservation Biology 15, n.º 1 (2009): 4. http://dx.doi.org/10.1071/pc090004.
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Australia has 12 major drainage basins, but most water use and extraction comes from the Murray- Darling Basin, despite not having Australia?s more populous cities. About 66% of surface water use in Australia is extracted from the rivers of the Murray-Darling Basin (NLWRA 2001). The ecological impacts are widespread and insurmountable: key ecosystems are in various stages of collapse. Many of these are conservation reserves and wetlands recognized for their international importance under the Ramsar Convention. Populations of native fish species are considered to be only at 10% of pre European levels with 46% of the 35 fish species now listed as threatened at state level (MDBC 2004). Waterbird populations are also declining significantly, sometimes up to 80% over a period of about 25 years (Kingsford and Thomas 2004; Nebel et al. 2008). Many communities of floodplain vegetation are also in decline. The River Murray no longer breaks through the sand barriers to naturally flow out to sea, with flow now only maintained by a dredge (costing ~$100,000 per week) to ensure that sand does not completely block the Murray mouth. The lower lakes are below sea level for the first time in more than 7,000 years and marine incursions into this freshwater ecosystem have allowed colonies of marine worms Ficopomatus enigmaticus to build their calcareous colonies on the backs of freshwater turtles and crabs weighing them down.
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Novikova, N. M., I. S. Iljina e I. N. Safronova. "Mapping the flood-plain vegetation of the Lower Volga River". Geobotanical mapping, n.º 1998-2000 (2000): 62–76. http://dx.doi.org/10.31111/geobotmap/1998-2000.62.
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In the paper the legend for 8 vegetation maps of key polygons s. 1 : 200 000, compiled by unified method, is given. The maps characterize the state of vegetation cover in different parts of the Lower Volga River (Volga-Akhtuba flood-plain and delta) in the late 90th. The Volga-Akhtuba flood-plain is well-divided into 2 morphogenetic types: the river-side flood-plain and the inner (central) one. Delta consists of numerous islands separated by channels and is subdivided into 3 parts: upper, middle and lower ones. At the mapping of flood-plain vegetation it is important to reveal the spatial variations in vegetation cover connected with regime of inundation, topography elevation, structure of surface, ground water table. The generalized legend to all maps is constructed according to ecological-dynamic principle reflecting the composition and structure of vegetation cover. Large divisions correspond to differentiation of vegetation at the level of main topographic types of territory: A. Vegetation of flood-plain, Б. Vegetation of delta. The divisions of the next rank are: I. Vegetation of river-side flood-plain and II. Vegetation of the inner flood- plain. Within the delta the following division are distinguished: 1. Forest-shrub- meadow and riparian-aquatic vegetation; 2. Desert vegetation. Mapping units proper (marked by numerical indices) characterize the phytocoenotical and floristic composition of vegetation as well as different patterns of its spatial structure and dynamics among the different elevation levels and forms of relief. Construction of Data Bases (DB) at mapping process has its specific features. Map organizes and differentiates the process of collecting information itself. The main instrument in this process is the map legend and the contents of mapping units. The botanical-cartographical DB suggests storing already synthesized and classified information, presented in form of mapping types of geobotanical polygons along with indices of environmental factors. The flood-plain vegetation of the Lower Volga River is represented by forests, shrub thickets, meadows, and aquatic-riparian Herbaceous communities. The forests are restricted mainly to the inner gentle ridges flood-plain. Oak forests (Quercus robur) are characteristic of only northern part of the Lower Volga River occuring between city of Volgograd and Kapustin Yar settlement. Willow forests (Salix alba) are spread throughout the all Lower Volga River (from Volgograd down to the Caspian Sea). They predominate in delta. In the middle part of delta the groves of Elaeagnus angustifolia appear. The channel-side natural levers of the lower seaward part of delta are occupied by forests of Salix alba. Shrubs thickets are less characteristic of these habitats; Tamarix ramosissima should be mentioned which appears south of 48°N in Volga- Akhtuba flood-plain in the limits of the Northern desert subzone. Forests of Populus nigra are wide-spread in the Volga-Akhtuba flood-plain from city of Volgograd southward up to Selitrennoye village. However they occupy habitats of middle topographical level. The same level in the river-side flood-plain and delta shrub thickets occupy. They are formed mainly by willows — Salix triandra, S. viminalis, S. acutifolia. Meadow vegetation predominate in the Lower Volga valley. Vegetation of high topographic level is formed by meadows of Calamagrostis epigeios, Bromopsis inermis, Elytrigia repens. Meadows of the middle topographic level are represented by grass-sedge communities. Meadows of the low topographic level are formed by communities of Carex acuta, Eleocharis spp., Elytrigia repens, Phragmites australis, Butomus umbellatus. The riparian-aquatic vegetation is formed by the communities of Phragmites australis, Typha spp., Scirpus lacustris, Phalaroiodes arundinacea, Butomus umbellatus, Sagittaria sagittifolia, Sparganium ramosum along the shores of water bodies and on the bottoms of depressions. Communities-indicators of soils with high salt content are characteristic of delta vegetation. On the overmoistened islands, free of water for a short time, with the surface salinification, the communities of Aeluropus spp., Crypsis aculeata, Bolboshoenus maritimus, Suaeda confusa, Salicornia europaea, Cynodon dactylon are spread.
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Guérette, Élise-Andrée, Clare Paton-Walsh, Ian Galbally, Suzie Molloy, Sarah Lawson, Dagmar Kubistin, Rebecca Buchholz et al. "Composition of Clean Marine Air and Biogenic Influences on VOCs during the MUMBA Campaign". Atmosphere 10, n.º 7 (10 de julho de 2019): 383. http://dx.doi.org/10.3390/atmos10070383.
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Volatile organic compounds (VOCs) are important precursors to the formation of ozone and fine particulate matter, the two pollutants of most concern in Sydney, Australia. Despite this importance, there are very few published measurements of ambient VOC concentrations in Australia. In this paper, we present mole fractions of several important VOCs measured during the campaign known as MUMBA (Measurements of Urban, Marine and Biogenic Air) in the Australian city of Wollongong (34°S). We particularly focus on measurements made during periods when clean marine air impacted the measurement site and on VOCs of biogenic origin. Typical unpolluted marine air mole fractions during austral summer 2012-2013 at latitude 34°S were established for CO2 (391.0 ± 0.6 ppm), CH4 (1760.1 ± 0.4 ppb), N2O (325.04 ± 0.08 ppb), CO (52.4 ± 1.7 ppb), O3 (20.5 ± 1.1 ppb), acetaldehyde (190 ± 40 ppt), acetone (260 ± 30 ppt), dimethyl sulphide (50 ± 10 ppt), benzene (20 ± 10 ppt), toluene (30 ± 20 ppt), C8H10 aromatics (23 ± 6 ppt) and C9H12 aromatics (36 ± 7 ppt). The MUMBA site was frequently influenced by VOCs of biogenic origin from a nearby strip of forested parkland to the east due to the dominant north-easterly afternoon sea breeze. VOCs from the more distant densely forested escarpment to the west also impacted the site, especially during two days of extreme heat and strong westerly winds. The relative amounts of different biogenic VOCs observed for these two biomes differed, with much larger increases of isoprene than of monoterpenes or methanol during the hot westerly winds from the escarpment than with cooler winds from the east. However, whether this was due to different vegetation types or was solely the result of the extreme temperatures is not entirely clear. We conclude that the clean marine air and biogenic signatures measured during the MUMBA campaign provide useful information about the typical abundance of several key VOCs and can be used to constrain chemical transport model simulations of the atmosphere in this poorly sampled region of the world.
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Saintilan, Neil, e Debashish Mazumder. "Fine-scale variability in the dietary sources of grazing invertebrates in a temperate Australian saltmarsh". Marine and Freshwater Research 61, n.º 5 (2010): 615. http://dx.doi.org/10.1071/mf09187.
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Saltmarsh floristic diversity declines with increasing latitude on the Australian east coast, with the dominant tropical C4 grass Sporobolus virginicus being replaced progressively by a suite of mostly succulent C3 species. The temperate Towra Point saltmarsh consists of a mosaic of vegetation communities, including stands of the C4 saltmarsh grass Sporobolus virginicus, and the C3 succulents Suaeda australis and Sarcocornia quinqueflora. The contrasting stable isotope signatures of these plants provide an opportunity to determine the extent to which plant material is contributing to the diet of grazing invertebrates inhabiting these communities. The grazing crabs Parasesarma erythrodactyla and Helograpsus haswellianus, and the snail Littoraria luteola, were sampled for their carbon and nitrogen isotope signatures. In the Sarcocornia communities, crab and snail δ13C signatures could not be matched to the signature of dominant plants, but were close to the fine benthic material on the marsh surface. In the Sporobolus community, the δ13C signatures of the same species were enriched and closer to that of the dominant plant. Results suggest that grazing herbivores feed over very small spatial ranges within mosaics of vegetation on locally sourced benthic material, with S. virginicus plant material making a contribution to dietary carbon where present.
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Henne, Anicia, Nathan Reid, Robert L. Thorne, Samuel C. Spinks, Tenten Pinchand e Alistair White. "Multi-Media Geochemical Exploration in the Critical Zone: A Case Study over the Prairie and Wolf Zn–Pb Deposits, Capricorn Orogen, Western Australia". Minerals 11, n.º 11 (22 de outubro de 2021): 1174. http://dx.doi.org/10.3390/min11111174.
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In this study, we compared traditional lithochemical sample media (soil) with hydrochemical (groundwater), biogeochemical (plant matter of mulga and spinifex), and other near-surface sample media (ferro-manganese crust), in a case study applied to mineral exploration in weathered terrain, through the critical zone at the fault-hosted Prairie and Wolf Zn–Pb (Ag) deposits in Western Australia. We used multi-element geochemistry analyses to spatially identify geochemical anomalies in samples over known mineralization, and investigated metal dispersion processes. In all near-surface sample media, high concentrations of the metals of interest (Zn, Pb, Ag) coincided with samples proximal to the mineralization at depth. However, the lateral dispersion of these elements differed from regional (several km; groundwater) to local (several 100′s of meters; solid sample media) scales. Zinc in spinifex leaves over the Prairie and Wolf deposits exceeded the total concentrations in all other sample media, while the metal concentrations in mulga phyllodes were not as pronounced, except for Ag, which exceeded the concentrations in all other sample media. These observations indicate potential preferential metal-specific uptake by different media. Pathfinder elements in vegetation and groundwater samples also indicated the Prairie Downs fault zone at the regional (groundwater) and local (vegetation) scale, and are, therefore, potentially useful tools to trace fault systems that host structurally controlled, hydrothermal Zn–Pb mineralization.
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Los, S. O. "Testing gridded land precipitation data and precipitation and runoff reanalyses (1982–2010) between 45° S and 45° N with normalised difference vegetation index data". Hydrology and Earth System Sciences 19, n.º 4 (14 de abril de 2015): 1713–25. http://dx.doi.org/10.5194/hess-19-1713-2015.
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Abstract. The realistic simulation of key components of the land-surface hydrological cycle – precipitation, runoff, evaporation and transpiration, in general circulation models of the atmosphere – is crucial to assess adverse weather impacts on environment and society. Here, gridded precipitation data from observations and precipitation and runoff fields from reanalyses were tested with satellite derived global vegetation index data for 1982–2010 and latitudes between 45° S and 45° N. Data were obtained from the Climate Research Unit (CRU), the Global Precipitation Climatology Project (GPCP) and Tropical Rainfall Monitoring Mission (TRMM; analysed for 1998–2010 only) and precipitation and runoff reanalyses were obtained from the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR), the European Centre for Medium-Range Weather Forecasts (ECMWF) and the NASA Global Modelling and Assimilation Office (GMAO). Annual land-surface precipitation was converted to annual potential vegetation net primary productivity (NPP) and was compared to mean annual normalised difference vegetation index (NDVI) data measured by the Advanced Very High Resolution Radiometer (AVHRR; 1982–1999) and Moderate Resolution Imaging Spectroradiometer (MODIS; 2001–2010). The effect of spatial resolution on the agreement between NPP and NDVI was investigated as well. The CRU and TRMM derived NPP agreed most closely with the NDVI data. The GPCP data showed weaker spatial agreement, largely because of their lower spatial resolution, but similar temporal agreement. MERRA Land and ERA Interim precipitation reanalyses showed similar spatial agreement to the GPCP data and good temporal agreement in semi-arid regions of the Americas, Asia, Australia and southern Africa. The NCEP/NCAR reanalysis showed the lowest spatial agreement, which could only in part be explained by its lower spatial resolution. No reanalysis showed realistic interannual precipitation variations for northern tropical Africa. Inclusion of runoff in the NPP prediction resulted only in marginally better agreement for the MERRA Land reanalysis and slightly worse agreement for the NCEP/NCAR and ERA Interim reanalyses.
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Los, S. O. "Testing gridded land precipitation data and precipitation and runoff reanalyses (1982–2010) between 45° S and 45° N with Normalized Difference Vegetation Index data". Hydrology and Earth System Sciences Discussions 11, n.º 12 (2 de dezembro de 2014): 13175–205. http://dx.doi.org/10.5194/hessd-11-13175-2014.
Texto completo da fonteResumo:
Abstract. The realistic simulation of key components of the land-surface hydrological cycle – precipitation, runoff, evaporation and transpiration – in general circulation models of the atmosphere is crucial to assess adverse weather impacts on environment and society. Here, gridded precipitation data from observations and precipitation and runoff fields from reanalyses were tested with satellite-derived global vegetation index data for 1982–2010 and latitudes between 45° S and 45° N. Data were obtained from the Climate Research Unit (CRU), the Global Precipitation Climatology Project (GPCP) and Tropical Rainfall Monitoring Mission (TRMM; analysed for 1998–2010 only) and (precipitation and runoff) reanalyses were obtained from the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR), the European Centre for Medium-Range Weather Forecasts (ECMWF) and the NASA Global Modelling and Assimilation Office (GMAO). Annual land-surface precipitation was converted to annual potential vegetation net primary productivity (NPP) and was compared to mean annual Normalized Difference Vegetation Index data measured by the Advanced Very High Resolution Radiometer (1982–1999) and MODIS (2001–2010). The effect of spatial resolution on the agreement between NPP and NDVI was investigated as well. The CRU and TRMM derived NPP agreed most closely with the NDVI data. The GPCP data showed weaker spatial agreement, largely because of their lower spatial resolution, but similar temporal agreement. MERRA Land and ERA Interim precipitation reanalyses showed similar spatial agreement as the GPCP data and good temporal agreement in semi-arid regions of the Americas, Asia, Australia and southern Africa. The NCEP/NCAR reanalysis showed the lowest spatial agreement which could only in part be explained by its lower spatial resolution. No reanalysis showed realistic interannual precipitation variations for northern tropical Africa. Inclusion of runoff in the NPP prediction resulted only in (marginally) better agreement for the MERRA Land reanalysis and worse agreement for the NCEP/NCAR and ERA Interim reanalyses.
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Moseby, K. E., e J. L. Read. "Population Dynamics and Movement Patterns of Bolam's Mouse, Pseudomys bolami, at Roxby Downs, South Australia." Australian Mammalogy 20, n.º 3 (1998): 353. http://dx.doi.org/10.1071/am98353.
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Basic ecological data were collected on Bolam's mouse, Pseudomys bolami, during a six year trapping study at Roxby Downs in northern South Australia. Pseudomys bolami inhabited mixed arid land systems in the Roxby Downs area, sheltering in the longitudinal orange sand dunes but foraging at night principally on the adjacent chenopod swales. Distances of up to 334m were traversed in a single night and recapture rates were high within trapping sessions but low between sessions suggesting wide-ranging movements and short-term residency. Dietary observations imply an omnivorous diet. Whilst the closely related P. hermannsburgensis is regarded as having an opportunistic breeding strategy, P. bolami reproduced opportunistically but also regularly in spring and early summer. Different reproductive strategies may be influenced by the latitudinal distribution of P. bolami near the southern margin of the arid-zone, where rainfall can occur at any time of year but winter rainfall is more predictable. This contrasts with P. hermannsburgensis, which inhabits more northerly arid areas where rainfall is erratic and unpredictable. There was a 10 fold fluctuation in P. bolami captures over the trapping period with numbers of P. bolami and house mice, Mus domesticus peaking 12 months after above average rains during 1992. Rodent captures remained high for two years afterwards. Although P. bolami persisted throughout the study period, M. domesticus was only present when conditions were above average. Trap success of P. bolami or M. domesticus did not vary between the five sub habitats at the 1 ha study site. However, trap success of P. bolami was positively related to vegetation cover, particularly cover of low bluebush, Maireana astrotricha. Maireana astrotricha may be important in providing both food and cover for P. bolami, a scenario consistent with the utilisation of spinifex, Triodia spp. by P. hermannsburgensis in the northern arid-zone. Past over- grazing of chenopod shrublands may have reduced cover and contributed to the suggested decline in the distribution of P. bolami.
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McHenry, Melinda T., Brian R. Wilson, Peter V. Lockwood, Christopher N. Guppy, Brian M. Sindel, Matthew K. Tighe, Ivor O. Growns e John M. Lemon. "The impact of individual Callitris glaucophylla (white cypress pine) trees on agricultural soils and pastures of the north-western slopes of NSW, Australia". Rangeland Journal 31, n.º 3 (2009): 321. http://dx.doi.org/10.1071/rj08052.
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Woody vegetation thickening occurs in agri-ecosystems worldwide, often with negative consequences for production. Dense Callitris glaucophylla (Joy Thomps. & L.A.S. Johnson) stands affect landscapes across NW NSW, Australia, and strategies to reduce tree density to levels which maintain biodiversity values alongside agricultural production are currently being sought. We investigated soil chemical and groundcover patterns associated with individual small and large C. glaucophylla trees at six sites of variable management history and lithology in NW NSW, Australia. We posed two questions: (1) do individual C. glaucophylla trees impose patterns on soil and groundcover (soil extractable P, C, N, S and pH, litter biomass, litter P and pasture cover), and, (2) if patterns exist, do they differ between tree sizes? Results showed that extractable P, C and pH decreased away from trees of both sizes, but significantly higher values were recorded adjacent to the stem of large trees. Litter biomass exhibited a strong site-related trend independent of soil variables. Positive correlations between litter and soil variables existed for some sites and not others, indicative of processes such as grazing which contribute to the transport of litter away from the tree. Irrespective of tree size ground-storey vegetation cover increased significantly away from the stem, presumably as a consequence of competition for soil water. Further results indicated that single C. glaucophylla trees enrich soils in patterns analogous to other species in similar environments worldwide. However, localised soil improvements must be weighed up against the negative effects of decreased groundcover associated with trees, and the potential for the species to re-seed prolifically into managed paddocks. Future research will discern the impact of individual C. glaucophylla trees at higher densities, where soil patterning may be modified by intense within-stand competition.
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Werner, P. A., I. D. Cowie e J. S. Cusack. "Juvenile tree growth and demography in response to feral water buffalo in savannas of northern Australia: an experimental field study in Kakadu National Park". Australian Journal of Botany 54, n.º 3 (2006): 283. http://dx.doi.org/10.1071/bt04135.
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Tree populations in the wooded savannas of northern Australia lack a well developed seed bank, but instead rely on a persistent ground layer of suppressed juvenile plants <1 m of indeterminate ages. The feral Asian water buffalo has been implicated as a factor in inhibiting the movement of juvenile trees to sapling stage. In a 6-year field study in Kakadu National Park, 656 juvenile plants were monitored for growth and survival, and in exploring the effects of buffalo, clipping surrounding vegetation and ambient fire. Buffalo were removed from one half of the sites across an environmental gradient in a landscape-scale experiment. Juvenile trees grew more slowly but fewer became dormant where buffalo were absent. Experimental clipping of surrounding vegetation produced significantly increased height at the buffalo-absent sites, but not at the buffalo-present sites, demonstrating that the positive effect of buffalo on growth was indirect, by reducing the competitive regime for juvenile trees. Within 3 years of removal of buffalo, ground-level green biomass increased 2–10 times and litter 1.3–2 times over a topographic gradient. Mortality of juvenile trees was not significantly different between buffalo-present and buffalo-absent sites when plots remained unburnt. By contrast, at buffalo-absent sites, three times more juveniles died after late dry-season fires than at unburnt sites, but there was no difference among buffalo-present sites. Overall, the total juvenile tree bank decreased by 7% where buffalo grazed and by 18% where buffalo had been removed. The study demonstrated a major mechanism(s) responsible for recorded changes in vegetation patterns of these savannas, whereby buffalo initiate a cascade of effects by changing ground-level biomass, which change competitive relationships and fuel loads, which then have an impact on tree growth and demography. The results are discussed with respect to dynamics of the juvenile tree bank and implications for long-term sustainability of these wooded savannas.
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Woodall, G. S., e C. J. Robinson. "Natural diversity of Santalum spicatum host species in south-coast river systems and their incorporation into profitable and biodiverse revegetation". Australian Journal of Botany 51, n.º 6 (2003): 741. http://dx.doi.org/10.1071/bt02118.
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The commercially valuable root hemiparasite Santalum spicatum (R.Br.) A.DC. (sandalwood) once grew throughout the medium- to low-rainfall areas of the south-western agricultural region of Australia; however, this resource has been exhausted by over-exploitation and clearing for agriculture. There has been growing interest from the farming community and other investors in the development of a plantation Santalum spicatum industry in southern Western Australia. This study investigated the distribution of remnant S. spicatum within the Pallinup River catchment and assessed the risk of S. spicatum population decline due to salinity. The natural range of host species at different sites (river catchments) across the south coast was also investigated. Remnant populations of S.�spicatum within and adjacent to the Pallinup River catchment were small (1–70 trees) and highly fragmented. The risk of further population decline due to salinity was concluded to be small because remnant trees were generally growing in well drained, sandy soils that were elevated above (median 9 m) their immediate drainage line. Across the seven river catchments surveyed, S. spicatum occurred in a range of vegetation associations and parasitised numerous species (68) from a wide range of genera and families. The suite of species exploited varied within and between catchments. Thirty species, including most monocots and Myrtaceae, were not successfully parasitised. Remnant S. spicatum always occurred on well drained soil types that supported open-woodland or mallee–heath communities. Sandalwood plantations, supported by numerous individuals of a range of host species (10–40 species), were shown to be productive in terms of sandalwood growth. The scale of the developing sandalwood plantation industry is likely to be small and unlikely to cover large areas of catchments. Thus, this industry alone is unlikely to address the salinity crisis through broadscale recharge management. However, additional to on-site recharge reduction, biodiverse host plantations may improve the prospects for biodiversity and rivers in salinising landscapes through the protection and enhancement of natural biodiversity, creation of new habitat, conservation of plant species and by providing a commercial incentive to protect biodiversity.
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Barrow, Lauren, Catherine L. Parr e James L. Kohen. "Biogeography and diversity of ants in Purnululu (Bungle Bungle) National Park and Conservation Reserve, Western Australia". Australian Journal of Zoology 54, n.º 2 (2006): 123. http://dx.doi.org/10.1071/zo06009.
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We describe the diversity, composition, functional group organisation and biogeography of ants in Purnululu National Park (128°19′E, 17°19′S) in Western Australia’s Kimberley region, located at a semi-arid/tropical zone boundary. Pitfall trapping collected a representative sample of ants from three main habitats within the park: spinifex, sandplain and gorges. In total, 154 species from 25 genera were collected. The richest genera were Melophorus, Iridomyrmex and Monomorium. Iridomyrmex was the most abundant genus, accounting for 80% of all individuals recorded in traps. Functional group composition was dominated by Dominant Dolichoderinae (41% of individuals collected) and Hot Climate Specialists (26%). Biogeographical composition was typical of semi-arid zone assemblages located on the overlap between Eyrean and Torresian zones: 50% of the species recorded represented Eyrean taxa, followed by 33% with Torresian affinities, and 10% Widespread. Differences in ant species richness, abundance and assemblage composition between the three habitat types were attributed to a combination of variation in vegetation structure and microhabitat composition. This paper provides baseline data on local ant communities in the semi-arid Kimberley, enabling a greater understanding of the conservation value of reserves within the Kimberley, one of Australia’s least studied bioregions.
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Dodsworth, Steven, Maarten J. M. Christenhusz, John G. Conran, Maïté S. Guignard, Sandra Knapp, Monika Struebig, Andrew R. Leitch e Mark W. Chase. "Extensive plastid-nuclear discordance in a recent radiation of Nicotiana section Suaveolentes (Solanaceae)". Botanical Journal of the Linnean Society 193, n.º 4 (24 de maio de 2020): 546–59. http://dx.doi.org/10.1093/botlinnean/boaa024.
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Abstract Nicotiana section Suaveolentes is the largest section of Nicotiana and is a monophyletic group of allotetraploid species. Most of the species are endemic to Australia, but three species occur on islands in the South Pacific as far east as French Polynesia and one species is native to Namibia. Here, we present phylogenetic results based on genome skimming, with near-complete taxon sampling and multiple accessions sampled for several species. These represent the first phylogenetic results for the section that include most recognized taxa, using wild-sourced material wherever possible. Despite known chromosome number and genome size changes in the section, there is little divergence in the ribosomal DNA operon (26S, 18.S and 5.8S plus associated spacers) and plastid genomes, with little to no taxonomic signal in plastome phylogenetic results and clear plastid-nuclear discordance. These results contrast with strong morphological differentiation (both floral and vegetative) between most of the core Australian taxa and obvious differences in ecological preferences. Together, these initial results portray Nicotiana section Suaveolentes as experiencing recent and ongoing radiation in the arid zone of Australia.
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Davis, R. A., e J. A. Wilcox. "Adapting to suburbia: bird ecology on an urban-bushland interface in Perth, Western Australia." Pacific Conservation Biology 19, n.º 2 (2013): 110. http://dx.doi.org/10.1071/pc130110.
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Birds in urban landscapes must contend with fragmented and degraded remnants of native vegetation and their survival may be dependent on factors such as their ability to disperse through and/or utilize the urban matrix. We examined the frequency of occurrence of birds in native bushland in Kings Park, Perth, Western Australia, and in nine adjacent suburban gardens. We quantified dispersal capacity by observing bird crossing frequency and height over a major six-lane road separating the bushland from adjacent gardens. Finally we quantified matrix utilisation by recording foraging behaviour in urban gardens and bushland. Native bushland had a higher species richness than urban gardens (30 versus 17 species) and 18 species were associated more strongly with bushland. Of these 18 species, 61% were never recorded in urban gardens. Gardens were typified by three generalist species, the Singing Honeyeater Lichenostomus virescens and the introduced Laughing Dove Spilopelia senegalensis and Spotted Dove S. chinensis. Three generalist species, the Red Wattlebird Anthochaera carunculata, Rainbow Lorikeet Trichoglossus haematodus, and Brown Honeyeater Lichmera indistincta were equally abundant in all habitats. Four of 18 bird species (Singing Honeyeater Red Wattlebird, Rainbow Lorikeet, and Australian Ringneck Barnardius zonarius) accounted for the majority of road crossing events. Urban gardens provided a rich resource for generalists and urban exploiters, all of which spent significantly more time foraging on nectar in gardens and significantly more time foraging on insects in bushland. We conclude that urban gardens provide habitat for some species that exploit nectar, but most species in bushland, particularly insectivores, do not use gardens. Our results indicate the importance of retaining well-managed bushland for supporting viable urban bird populations.
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Verbeke, T., J. Lathière, S. Szopa e N. de Noblet-Ducoudré. "Impact of future land cover changes on HNO<sub>3</sub> and O<sub>3</sub> surface dry deposition". Atmospheric Chemistry and Physics Discussions 15, n.º 13 (8 de julho de 2015): 18459–85. http://dx.doi.org/10.5194/acpd-15-18459-2015.
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Abstract. Dry deposition is a key component of surface–atmosphere exchange of compounds, acting as a sink for several chemical species. Meteorological factors, chemical properties of the trace gas considered and land surface properties are strong drivers of dry deposition efficiency and variability. Under both climatic and anthropogenic pressure, the vegetation distribution over the Earth has been changing a lot over the past centuries, and could be significantly altered in the future. In this study, we perform a modeling investigation of the potential impact of land-cover changes between present-day (2006) and the future (2050) on dry deposition rates, with special interest for ozone (O3) and nitric acid vapor (HNO3), two compounds which are characterized by very different physico-chemical properties. The 3-D chemistry transport model LMDz-INCA is used, considering changes in vegetation distribution based on the three future projections RCPs 2.6, 4.5 and 8.5. The 2050 RCP 8.5 vegetation distribution leads to a rise up to 7 % (+0.02 cm s−1) in VdO3 and a decrease of −0.06 cm s−1 in VdHNO3 relative to the present day values in tropical Africa, and up to +18 and −15 % respectively in Australia. When taking into account the RCP 4.5 scenario, which shows dramatic land cover change in Eurasia, VdHNO3 increases by up to 20 % (annual-mean value) and reduces VdO3 by the same magnitude in this region. When analyzing the impact of dry deposition change on atmospheric chemical composition, our model calculates that the effect is lower than 1 ppb on annual mean surface ozone concentration, for both for the RCP8.5 and RCP2.6 scenarios. The impact on HNO3 surface concentrations is more disparate between the two scenarios, regarding the spatial repartition of effects. In the case of the RCP 4.5 scenario, a significant increase of the surface O3 concentration reaching locally up to 5 ppb (+5 %) is calculated on average during the June–August period. This scenario induces also an increase of HNO3 deposited flux exceeding locally 10 % for monthly values. Comparing the impact of land-cover change to the impact of climate change, considering a 0.93 °C increase of global temperature, on dry deposition velocities, we estimate that the strongest increase over lands occurs in the North Hemisphere during winter especially in Eurasia, by +50 % (+0.07 cm s−1) for VdO3 and +100 % (+0.9 cm s−1) for VdHNO3. However, different regions are affected by both changes, with climate change impact on deposition characterized by a latitudinal gradient, while the land-cover change impact is much more heterogeneous depending on vegetation distribution modification described in the future RCP scenarios. The impact of long-term land-cover changes on dry deposition is shown to be non-negligible and should be therefore considered in biosphere-atmospheric chemistry interaction studies in order to have a fully consistent picture.
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Dong, Qian, Qingqing Zhang, Anbang Liao, Chi Xu e Maosong Liu. "Plant Adaptability and Vegetation Differentiation in the Coastal Beaches of Yellow–Bohai Sea in China". International Journal of Environmental Research and Public Health 19, n.º 4 (16 de fevereiro de 2022): 2225. http://dx.doi.org/10.3390/ijerph19042225.
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To identify the key soil factors influencing the vegetation differentiation in the coastal tidal flats of the Yellow−Bohai Sea in China, this study investigated the corresponding relationship between the Spartina alterniflora (SA), Suaeda salsa (SS), and Phragmites australis (PA) communities and their respective soil factors with published data, and combined the ecological strategy for analysis. The results showed a corresponding relationship between community and soil factors. The SA community had a lower bulk density (BD) and higher soil total nitrogen (TN), and the SS community was the opposite, while the PA community had the lowest salinity and higher TN. BD, salinity and TN acted as the main soil factors driving vegetation differentiation, but the explained proportion of the three factors to vegetation differentiation changed by season and region. Considering that higher TN facilitates the competitors, salinity represents the environmental stresses, and BD is positively related to the frequency of perturbation in the specific habitat in the study area, SA, SS and PA could be recognized as C–S, S–R and C strategic species to some extent. It is likely that some coexistent mechanisms for invasive and local species will be developed, especially the SS community which seriously shrunk recently but served as an important habitat for waterfowls in tidal flat habitats.
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Dickman, Christopher R., Adele S. Haythornthwaite, Gayle H. McNaught, Paul S. Mahon, Bobby Tamayo e Mike Letnic. "Population dynamics of three species of dasyurid marsupials in arid central Australia: a 10-year study". Wildlife Research 28, n.º 5 (2001): 493. http://dx.doi.org/10.1071/wr00023.
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This study investigated the population dynamics of three species of dasyurid marsupials in sand ridge habitat of the Simpson Desert, western Queensland, over a 10-year period between March 1990 and December 1999. The lesser hairy-footed dunnart (Sminthopsis youngsoni), was captured most consistently over the period of study, followed by the wongai ningaui (Ningaui ridei), and the mulgara (Dasycercus cristicauda). Rates of recapture were low (4.5–22.2%), probably because individuals of each species are very mobile. All species bred in late winter or early spring when animals were aged at least 8–10 months, and independent juveniles first appeared usually in summer. S. youngsoni reared a second litter in late spring or early summer in 3 of the 10 years studied, when the availability of food was likely to have been high; neither N. ridei nor D. cristicauda were known to attempt a second litter within a season. To explore factors that might influence population dynamics, we compared capture rates of each species with measures of rainfall, temperature, vegetation cover, abundance of predators [feral cats (Felis catus), red foxes (Vulpes vulpes), and goannas (Varanus spp.)], dragons, other dasyurids and indices of food abundance. The abundance of S. youngsoni appeared to depend primarily on the cover of spinifex 7–9 months earlier, that of D. cristicauda was related most strongly to rainfall 7–9 months earlier, while that of N. ridei was related to minimum temperature lagged by 1–3 months. While the dynamics of other arid-zone mammals are driven demonstrably by interactions between rainfall, resource availability and predation, our findings suggest that dasyurids have limited flexibility in their life histories and are influenced more subtly and by factors such as facilitation that are just beginning to become apparent.
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Parsons, Scott A., Alex Kutt, Eric P. Vanderduys, Justin J. Perry e Lin Schwarzkopf. "Exploring relationships between native vertebrate biodiversity and grazing land condition". Rangeland Journal 39, n.º 1 (2017): 25. http://dx.doi.org/10.1071/rj16049.
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Although commercial grazing can degrade natural habitats, sustainably grazed land may be effective for wildlife conservation. Thus, land condition frameworks that assess the landscape quality of grazed land may also be useful for assessment of habitat quality for wildlife. However, the relationship between the condition of grazed land and native biodiversity is mostly unknown, and this knowledge gap must be addressed to adequately balance commercial production and conservation. In the present case study we determined the relevance of a widely used grazing land condition scale to understanding native vertebrate species richness and abundance (birds, reptiles, amphibians, mammals and all these vertebrate classes grouped) in grazed rangelands in northern Australia (~24–13°S; annual rainfall ranging from >1200 to <400 mm), sampled over approximately 10 years from 17 unique sites, containing 381 1-ha study plots. We defined the land condition scale relative to climate and comprehensive assessment of habitat attributes, and then described the relationships between land condition, habitat and biodiversity. The land condition scale partially explained richness and abundance patterns only for mammals (especially rodents), which tended to be higher in better-condition pasture. For other vertebrate groups, the scale was a very poor descriptor of richness and abundance. The land condition scale was not useful to assess wildlife diversity primarily because ‘woody thickening’ (increases in woody vegetation on grazed land, including shrubs and trees) lowers the ‘grazing value’ of land while also generally promoting vertebrate diversity. In line with this, biodiversity decreased with increasing bare ground and erosion, together with, and in the absence of, vegetation cover (i.e. desertification), consistent with grazing land degradation. The present study supports observations that land clearing and reductions in woody vegetation on grazed rangelands are particularly detrimental to native vertebrates.
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Kelley, G., A. P. O'Grady, L. B. Hutley e D. Eamus. "A comparison of tree water use in two contiguous vegetation communities of the seasonally dry tropics of northern Australia: the importance of site water budget to tree hydraulics". Australian Journal of Botany 55, n.º 7 (2007): 700. http://dx.doi.org/10.1071/bt07021.
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Tree water use in two contiguous communities (eucalypt open-forest and Melaleuca paperbark forest) was measured in tropical Australia, over a 2-year period. The aims of the study were to (1) quantify daily and seasonal patterns of water use in each community, (2) compare patterns of water use among the communities and (3) compare relationships among tree size, sapwood area and water use within the two contrasting vegetation communities. Access to deep soil water stores and the effect of run-on from the eucalypt forest resulted in a relatively high pre-dawn water potential throughout the year, particularly for Melaleuca forest. There were no differences in daily rates of water use, expressed on a sapwood area (Q s) basis, between the two eucalypt species examined (Eucalyptus miniata Cunn. Ex Schauer and E. tetrodonta F.Muell) at any time in the eucalypt forest. For both the eucalypt and Melaleuca forests, there was less seasonal variation in water use expressed on a leaf area (Q l) basis than on a Q s basis, and neither year nor season were significant factors in Q l. In the mono-specific Melaleuca forest, Q s was not significantly different between years or seasons. Water use on a Q l basis was similarly not significantly different between years or seasons in the Melaleuca forest. Leaf area index (LAI) of the eucalypt forest was about half of that of the Melaleuca forest throughout the year but sapwood area per hectare was 33% larger in the eucalypt than the Melaleuca forest, despite the basal area of the Melaeuca forest being almost double that of the eucalypt forest. There was no significant difference in stand water use (mm day–1) between eucalypt and Melaleuca forests during 1998; however, in 1999 Melaleuca stand water use was larger than that of the eucalypt forest. Because of the enhanced dry-season availability of water in the Melaleuca forest and its larger LAI, average annual water use of the Melaleuca forest was almost 60% larger than that of the eucalypt forest. Despite differences in Q l, Q s and annual water use between forests, the ratio of LAI to stand water use was similar for all seasons in both forests. The applicability of ‘universal rules’ linking tree water use and tree hydraulics and the importance of ecosystem location on site water budgets and plant adaptations are discussed.
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Verbeke, T., J. Lathière, S. Szopa e N. de Noblet-Ducoudré. "Impact of future land-cover changes on HNO<sub>3</sub> and O<sub>3</sub> surface dry deposition". Atmospheric Chemistry and Physics 15, n.º 23 (9 de dezembro de 2015): 13555–68. http://dx.doi.org/10.5194/acp-15-13555-2015.
Texto completo da fonteResumo:
Abstract. Dry deposition is a key component of surface–atmosphere exchange of compounds, acting as a sink for several chemical species. Meteorological factors, chemical properties of the trace gas considered and land surface properties are strong drivers of dry deposition efficiency and variability. Under both climatic and anthropogenic pressure, the vegetation distribution over the Earth has been changing a lot over the past centuries and could be significantly altered in the future. In this study, we perform a modeling investigation of the potential impact of land-cover changes between the present day (2006) and the future (2050) on dry deposition velocities at the surface, with special interest for ozone (O3) and nitric acid (HNO3), two compounds which are characterized by very different physicochemical properties. The 3-D chemistry-transport model LMDz-INCA is used, considering changes in vegetation distribution based on the three future projections, RCPs 2.6, 4.5 and 8.5, and present-day (2007) meteorology. The 2050 RCP 8.5 vegetation distribution leads to a rise of up to 7 % (+0.02 cm s−1) in the surface deposition velocity calculated for ozone (Vd,O3) and a decrease of −0.06 cm s−1 in the surface deposition velocity calculated for nitric acid (Vd,HNO3) relative to the present-day values in tropical Africa and up to +18 and −15 %, respectively, in Australia. When taking into account the RCP 4.5 scenario, which shows dramatic land-cover change in Eurasia, Vd,HNO3 increases by up to 20 % (annual-mean value) and reduces Vd,O3 by the same magnitude in this region. When analyzing the impact of surface dry deposition change on atmospheric chemical composition, our model calculates that the effect is lower than 1 ppb on annual-mean surface ozone concentration for both the RCP 8.5 and RCP 2.6 scenarios. The impact on HNO3 surface concentrations is more disparate between the two scenarios regarding the spatial repartition of effects. In the case of the RCP 4.5 scenario, a significant increase of the surface O3 concentration reaching locally by up to 5 ppb (+5 %) is calculated on average during the June–August period. This scenario also induces an increase of HNO3 deposited flux exceeding locally 10 % for monthly values. Comparing the impact of land-cover change to the impact of climate change, considering a 0.93 °C increase of global temperature, on dry deposition velocities, we estimate that the strongest increase over lands occurs in the Northern Hemisphere during winter, especially in Eurasia, by +50 % (+0.07 cm s−1) for Vd,O3 and +100 % (+0.9 cm s−1) for Vd,HNO3. However, different regions are affected by both changes, with climate change impact on deposition characterized by a latitudinal gradient, while the land-cover change impact is much more heterogeneous depending on vegetation distribution modification described in the future RCP scenarios. The impact of long-term land-cover changes on dry deposition is shown to be significant and to differ strongly from one scenario to another. It should therefore be considered in biosphere–atmospheric chemistry interaction studies in order to have a fully consistent picture.
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Bolpagni, Rossano, e Andrea Piotti. "Hydro-hygrophilous vegetation diversity and distribution patterns in riverine wetlands in an agricultural landscape: a case study from the Oglio River (Po Plain, Northern Italy)". Phytocoenologia 45, n.º 1 (1 de julho de 2015): 69–84. http://dx.doi.org/10.1127/0340-269x/2014/0044.
Texto completo da fonteResumo:
In the European plains, up to eighty percent of riverine wetlands have been lost due to alteration of hydrological regime and catchment exploitation. This condition is expected to be further negatively exacerbated by climate change. To better understand the observed change in distribution patterns of hydro-hygrophilous vegetation in temperate and Mediterranean floodplains, a vegetation survey was conducted within the lower Oglio River reach in Northern Italy. This river is a mid-size, altered and nutrient-rich left tributary of the Po River. During the 2008 growing season, a total of 60 marginal aquatic habitats were investigated. Overall, 37 vegetation communities were detected, showing a clear predominance of hygrophilous herbaceous plant communities both in terms of representativeness (55.1%) and diversity (54.1%) with respect to woody (22.9% and 10.8%, respectively), and obligate aquatic vegetation (22.0% and 35.1%, respectively). Our main findings were (1) the widespread presence of highly opportunistic, non-native and invasive hygrophilous plant communities (largely dominated by Amorpha fruticosa, Phragmites australis s.l., Amaranthus spp., Bidens spp., and Cyperus spp.), and (2) the limited distribution of hydrophyte vegetation usually dominated by pleustophytes (e.g., Spirodela polyrhiza and Lemna spp.). The present study confirms the dominance of secondary plant communities characterized by the widespread presence of alien species in lowland over-exploited riverscapes, coupled with a low local representativeness of native willow (Salix alba, S. cinerea) communities and anchored macrophyte (batrachid, ceratophyllid, elodeid, myriophyllid) meadows. Total vegetation diversity is consistent with previous studies in similar ecological contexts; on the other hand, at the site scale, the diversity values were extremely low. This is especially true for the aquatic vegetation, and can be related to the high water turbidity and chlorophyll-a concentrations that prevent the establishment and colonization of submerged and rooted hydrophytes. Consequently, we stress the need for metabolic and biogeochemical indicators to assess the actual trophic status of lowland wetlands in order to clarify their potential to be restored.
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Start, A. N. "The mistletoe flora of southern Western Australia, with a particular reference to host relationships and fire". Australian Journal of Botany 63, n.º 8 (2015): 636. http://dx.doi.org/10.1071/bt15028.
Texto completo da fonteResumo:
The mistletoe flora of southern Western Australia was studied over a 30-year period with a particular emphasis on distributions, host relationships and fire. The study area encompassed Western Australia south of ~26° S. It included all the South-west Botanical Province and southern components of the Eremaean Botanical Province, with the northern boundary corresponding with bioregional boundaries. Vegetation ranges from wet and dry sclerophyll forest through woodlands and heaths to deserts. The mistletoe flora comprises 21 taxa, 19 in the Loranthaceae and two in the Santalaceae. They infect 153 species in 25 genera and 15 families. The Fabaceae provides hosts to more taxa than any other family; however, the genus with most host species, Eucalyptus (Myrtaceae), supports only two mistletoe species, one of which barely enters the study area. Melaleuca (also Myrtaceae) is host to seven species. The number of mistletoe species per bioregion ranges from 0 to 18, with 12 species in the seven bioregions of the South-west Botanical Province and 20 in the six bioregions of Eremaean Botanical Province that are within the study area. In both provinces, diversity is lower in coastal areas and higher in more arid, inland areas. Most mistletoe habitats in the study area are fire-prone. One species is probably capable of resprouting whereas all other taxa are obligate seeders. With no means of in situ seed storage, post-fire recovery depends on seed importation. Fire is the most pervasive (but not the only) threatening process operating today. However, fire management in more populous agricultural and urban areas safeguards many populations in the South-west Province.