Cunninghamia : A Journal of Plant Ecology for Eastern Australia, Volume 12, Issue 4 (2012)
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Species may become vulnerable because of a reduction of habitat, leading to reduction of population sizes and an increase in geographic isolation between populations, leading to genetic drift that may result in reduced reproductive fitness. The restricted sedge Gahnia insignis S.T. Blake (family Cyperaceae), occurring in isolated pockets in north-east New South Wales and Queensland, was compared to a closely related, sympatric, common and widespread Gahnia clarkei Benl for flowering phenology and reproductive success. Flowering patterns, examination of pollen, fertilisation and embryo development and seed-ovule ratios show Gahnia clarkei has every indication of successful sexual reproduction, but that Gahnia insignis appears to reproduce mostly by vegetative means, with an occasional sexual event. This was due to the rarity of pollination opportunities, and to poor pollen viability and pollen quantity, resulting in a much lower seed-ovule ratio than Gahnia clarkei. The additional high level of vegetative reproduction in Gahnia insignis suggests it may be largely clonal in Nightcap National Park. A genetic study of the whole distribution would add knowledge of the species genetic diversity and differentiation between populations.
The vegetation of the Mount Murchison and Wilga areas, Paroo Darling National Park (latitude 31o00’-32o 40’S and longitude 142o10’-144o25’E) in north western New South Wales was assessed using intensive quadrat sampling and mapped using extensive ground truthing and interpretation of aerial photograph and Landsat Thematic Mapper satellite images. In the survey 237 vascular plant species including 37 (15.6%) exotic species, from 46 families were recorded. Seventeen vegetation communities were identified and mapped, 15 for Mount Murchison area and 13 for the Wilga area. The most widespread for Mount Murchison being Maireana pyramidata low open shrubland, Flindersia maculosa low open woodland, Muehlenbeckia florulenta open shrubland and Eucalyptus coolabah / Eucalyptus largiflorens open woodland. The most widespread for Wilga being Muehlenbeckia florulenta open shrubland and Eucalyptus coolabah / Eucalyptus largiflorens open woodland. Many of these communities have been impacted by a history of 150 years of pastoral use.
Pentzia is a predominantly southern African genus of low shrubs, many of which are important fodder plants for sheep in semi-arid and arid areas. Attempts since 1869 to introduce Pentzia incana to south-eastern Australia for sheep fodder are described. One of these, near Koonamore in north-eastern South Australia, was temporarily successful there and may have led to the only extant stands in Australia – two well-established populations at Mount Serle in the northern Flinders Ranges. These events are related to the biology of the species and to similar events concerning the deliberate introduction of the species to Arizona. These data are discussed in terms of current ideas about plant introduction, dispersal, invasion and the concept of sleeper weeds. Pentzia globosa is currently known from a single stand in Australia, at Bundaleer Forest in the Mid North of South Australia. The history of this occurrence is briefly discussed. For both species, it is concluded that regular monitoring is needed in case of rapid spread and that further data are needed on the extent to which they exhibit weedy behaviour in southern Africa.
The listed threatened plant taxa within the South Coast Region of New South Wales (Helensburgh to Batemans Bay, as designated by the NSW National Parks and Wildlife Service) are documented. Of the 100 NSW listed taxa, 69 are also listed by the Commonwealth, while two additional taxa are only listed by the Commonwealth. An analysis of the individual taxa and the 62 conservation reserves in the region, found that 30 taxa can with confidence be said to be adequately reserved, while 50 are assessed as inadequately reserved; for the remaining 22 taxa, reservation status is unknown. Examples of challenges for the conservation of threatened plants in the region are examined; these challenges have relevance well beyond the South Coast Region. Managing for individual plant species may be hampered by a lack of basic ecological information; this is particularly so for the rarer species such as orchids. One of the main areas where information is lacking is the response of most species to bushfire. Conservation on private land is becoming an increasingly important and challenging area for plant species conservation as the last large areas of public land are dedicated for one purpose or another. A more co-ordinated approach to conservation on private land may produce improved outcomes for many inadequately reserved taxa.
Vegetation structure and floristics of granite landforms in the South-west Slopes of New South Wales
(2012)
We describe the natural vegetation structure and floristics of 44 small-sized granite outcrops (inselbergs) in agricultural landscapes in the South-west Slopes (SWS) bioregion of New South Wales (35º 26’ S, 147º 23’ E to 35º 58’ S, 146º 59’E) and their relationships with geomorphology. We provide a list of 196 species (117 natives and 79 exotics). We found that structurally complex outcrops supported a greater diversity of native ground cover species and fewer exotic species than structurally simple outcrops. Tor landforms lacked vegetation structural complexity and were deficient in native shrubs, mid-storey and over-storey species but typically supported exotic grasses and broadleaved exotic weeds. Floristic composition differed among landforms and cluster analysis revealed highly dissimilar native plant communities among outcrops. Our study highlights the need to rehabilitate tor landforms and manage a broad spectrum of outcrops to conserve floristic diversity in agricultural landscapes. Selecting genetically diverse species for replanting, considering the density and spatial arrangement of plantings, and controlling invasive plants and feral herbivorous animals are fundamental issues in restoring granite outcrop vegetation in the SWS bioregion.
Spring wetlands on the Strathbogie plateau were mapped using recent aerial photography to estimate their current and former extent. The floristic composition and relationships of the vegetation with topographic, environmental and land use variables were interpreted from an analysis of quadrat data. Wetland condition, threats to their persistence and future management requirements were also identified. More than half of the original wetland vegetation in the study area appears to have been lost, probably as a result of clearing for agriculture. Nine floristic assemblages, identified using agglomerative hierarchical clustering, were identified on acidic to mildly alkaline peat in five different hydrogeomorphic settings. One of these assemblages (Low Open Sedgeland) was uniquely confined to spring-fed mounds, not previously described in Victoria. A key to identification of these groups was developed. Floristic composition was correlated with climate and site disturbance but charcoal throughout sediment cores suggested that historical disturbance regimes included fire. Forested sites at higher elevations where grazing pressure appears to have been less intense were the least disturbed sites. Approximately 60% of the wetlands surveyed were assessed as showing signs of soil moisture loss but there was no evidence that water extraction via dams and known bores was a significant driver of current vegetation composition. Threats requiring management were related to habitat destruction and degradation, dysfunction of physical and biological processes, and changes to disturbance regimes. Establishment of native vegetation buffers and biomass management are likely to be of benefit for future management of spring wetland vegetation.
Newnes Plateau Shrub Swamps are a series of low nutrient temperate montane peat swamps around 1100 m elevation in the upper Blue Mountains, west of Sydney (lat 33° 23’ S; long 150° 13’E). Transect-based vegetation studies show a closely related group of swamps with expanses of permanently moist, gently sloping peatlands. Vegetation patterns are related to surface hydrology and subsurface topography, which determine local peat depth. While there is evidence that a group of the highest elevation swamps on the western side of the Plateau are more dependent on rainwater, the majority of swamps, particularly those in the Carne Creek catchment, and east and south of it, may beconsidered primarily groundwater dependent with a permanently high watertable maintained by groundwater aquifers. An integral part of the swamps are a number of threatened groundwater dependent biota (plants–Boronia deanei subsp. deanei, Dillwynia stipulifera, dragonfly– Petalura gigantea, lizard– Eulamprus leuraensis), which are obligate swamp dwellers. This association of dependence leaves the entire swamp ecosystem highly susceptible to threats from any loss of groundwater, the current major one being the impact of damage to the confining aquicludes, aquitards, aquifers and peat substrates as a result of subsidence associated with longwall mining. Impacts on the swamps may also result from changes to hydrology through damming of creeks, mine waste water discharge, increased moisture competition from pine plantations, recreational motorbike and off-road vehicle tracks and climate change. If these groundwater dependent ecosystems do not receive protection from activities such as longwall mining subsidence, significant ecological damage is unlikely to be avoided or able to be mitigated even where provisions of the Commonwealth Environment Protection and Biodiversity Conservation and NSW Threatened Species Conservation Acts apply to groundwater dependent swamps and biota. The importance of the highest elevation part of the Plateau for a number of restricted (some endemic) plant species is also discussed.
Aerial photo interpretation of high resolution airborne imagery (ADS40) was used in a three-dimensional (3-D) digital Geographic Information System (GIS) environment to map native plant communities defined in the NSW Vegetation Classification and Assessment (NSW VCA) in central-southern New South Wales. NSW VCA plant community types form part of the NSW BioMetric vegetation type dataset underpinning NSW natural resource management (NRM) planning frameworks. This region was previously devoid of detailed vegetation mapping. In addition to developing a novel method for mapping plant communities, the use of ADS40 imagery allowed for capture of multiple attributes in each map polygon including attributes pertaining to dominant species and vegetation condition. Such data informs multi-attribute models used in conservation planning, providing utility beyond that of a singular plant community map.
A total of 546,150 hectares of native vegetation in 100 native plant communities was mapped across the study area (Coolamon, Cootamundra, Junee, Lockhart, Narrandera, Tarcutta, Urana, Wagga Wagga and Yanco 1:100,000 mapsheets and Ariah Park, Wallaroobie Range and Yoogali 1:50,000 mapsheets). Exotic pine plantations and native species plantings were also mapped. Remnants of greater than one hectare were captured through on-screen GIS digitising at scales of approximately 1:4,000. The plant community type mapping was independently assessed using random blind validation points as having a user accuracy of 87%. This level of accuracy demonstrates the applicability of the methodology for mapping open forests, woodlands and open woodlands of south-eastern Australia and probably other vegetation elsewhere. Such accurate mapping provides end users with confidence when using vegetation maps in environmental assessment and land use planning.