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Mires or peat swamps have a restricted distribution in Australia and are limited to areas where hydrological inputs exceed evapotranspiration. In NSW, mires are restricted to the coast, adjacent ranges or tablelands, and along the Great Dividing Range; most are listed as threatened ecological communities under State or Commonwealth legislation. Due primarily to the relatively high rainfall and suitable geology, the Blue Mountains region includes a number of such threatened mire ecological communities. Most of these mire types are largely included within the Greater Blue Mountains World Heritage Area, although there are notable exceptions, such as the endangered Newnes Plateau Shrub Swamps.
This paper reports on a little-known group of diverse, relatively isolated and largely unprotected mires, in a relatively low rainfall area in the upper Cudgegong River catchment, east of Rylstone in the NSW Central Tablelands, and of their floristic, hydrogeomorphic and typological relationship with other mires of the Blue Mountains. They can be broadly divided into montane bogs, montane fens and hanging swamps. Particular attention is focussed on the largest and most diverse one, Rollen Creek swamp, which contains all three types. It is hoped that highlighting this hitherto unrecognised group of high conservation-value mires will contribute to their improved conservation and encourage further research into mires of eastern NSW.
Floodplains and other wetlands depend on seasonal river flooding and play an important role in the terrestrial water cycle. They influence evapotranspiration, water storage and river discharge dynamics, and they are the habitat of a large number of animals and plants. Thus, to assess the Earth’s system and its changes, a robust understanding of the dynamics of floodplain wetlands including inundated areas, water storages, and water flows is required.
This PhD thesis aims at improving the modeling of large floodplains and wetlands within the global-scale hydrological model WaterGAP, in order to better estimate water flows and water storage variations in different storage compartments. Within the scope of this thesis, I have developed a new approach to simulate dynamic floodplain inundation on a global-scale. This approach introduces an algorithm into WaterGAP, which has a spatial resolution of 0.5 degree (longitude and latitude) globally. The new approach uses subgrid-scale topography, based on high-resolution digital elevation models, to describe the floodplain elevation profile within each grid cell by applying a hypsographic curve. The approach comprises the modeling of a two-way river-floodplain interaction, the separate downstream water transport within the river and the floodplain – both with temporally and spatially different variable flow velocities – and the floodplain-groundwater interactions. The WaterGAP version that includes the floodplain algorithm, WaterGAP 2.2b_fpl, estimates floodplain and river water storage, inundated area and water table elevation, and also simulates backwater effects.
WaterGAP 2.2b_fpl was applied to model river discharge, river flow velocity, water storages, water heights and surface water extent on a global-scale. Model results were comprehensively validated against ground observations and remote sensing data. Overall, the modeled and observed data are in agreement. In comparison to the former version WaterGAP 2.2b, the model performance has improved significantly. The improvements are most remarkable in the Amazon River basin. However, the seasonal variation of surface water extent and total water storage anomalies are still too low in many regions on the globe when compared to observations. A detailed analysis of the simulated results suggests that in the Amazon River basin the introduction of backwater effects is important for realistically simulating water storages and surface water extent. Future efforts should focus on the simulation of water levels in order to better model the flow routing according to water slope. To further improve the model performance in specific regions, I recommend that the globally constant model parameters that affect inundation initiation, river-floodplain interaction, DEM correction for vegetation, and backwater amount at basin or subbasin-scale be adjusted.
Wet grasslands once covered a large area in the lowlands of northern Germany, but have declined since several decades as a result of land use intensification. Permanent plot data from such grasslands in the region that would allow to assess the extent of changes in species composition and richness are still rare. Here, we present a re-visitation study of 52 quasi-permanent plots from the Stedinger Land area in the basin of the river Weser near Bremen, comparing quadrat data between 1948 and 2015. In 1948, the grasslands were characterized by species typical of wet, moderately fertile grasslands belonging to the Bromo-Senecionetum aquatici (Bromion racemosi), including 15 species currently classified as threatened. Until 2015, the vegetation had changed strongly: almost all indicators of wet grasslands had either declined or completely vanished, whereas more nutrient-demanding species of less wet soils had increased, especially grasses. The cumulative number of species had declined by 50%, while mean plot species richness had decreased by 64.6%, mainly resulting from the pronounced loss of many herbs. A comparison of mean Ellenberg indicator values suggested that the plots had become drier, but also more base- and nutrient-rich, most likely triggered by the intensification of land use with drainage and fertilization as well as more frequent and earlier cutting. Our study reflects the dramatic loss of plant species diversity in wet grasslands over the past 60−70 years in areas not preserved and properly managed, and it documents the need for protecting remnants of these grasslands and for restoring wet grassland areas by re-wetting, nutrient removal and the transition to a less intensive land use.
Naree and Yantabulla stations (31,990 ha) are found 60 km south-east of Hungerford and 112 km north-west of Bourke, New South Wales (lat. 29° 55'S; long. 150°37'N). The properties occur on the Cuttaburra Creek within the Mulga Lands Bioregion. We describe the vegetation assemblages found on these properties within three hierarchical levels (Group, Alliance & Association). Vegetation levels are defined based on flexible UPGMA analysis of coverabundance scores of all vascular plant taxa. These vegetation units are mapped based on extensive ground truthing, SPOT5 imagery interpretation and substrate. Three ‘Group’ level vegetation types are described: Mulga Complex, Shrublands Complex and Floodplain Wetlands Complex. Within these Groups nine ‘Alliances’ are described: Rat’s tail Couch – Lovegrass Grasslands, Canegrass Grasslands, Lignum – Glinus Shrublands, Coolibah – Black Box Woodlands, Turpentine – Button Grass – Windmill Grass Shrublands, Turpentine – Hop Bush – Kerosene Grass shrublands and Mulga Shrublands. Sixteen ‘Associations’ are described 1) Mulga – Poplar Box Shrubland, 2) Mulga – Poplar Box – Bastard Mulga Shrubland, 3) Turpentine – Hop Bush – Senna Shrubland, 4) Turpentine – Elegant Wattle – Boobialla Shrubland, 5) Turpentine – Hop Bush – Daisy Bush Shrubland, 5) Belah – Rosewood – Turpentine Bush Shrubland, 6) Belah – Rosewood – Turpentine Bush Shrubland, 7) Ironwood – Leopardwood – Supplejack Shrubland, 8) Yapunyah – Black Box – River Cooba Woodland, 9) Coolibah – River Cooba – Yapunyah Woodland, 10) Rat’s tail Couch – Lovegrass – Fairy Grass Grassland and Herbfield, 11) Rat’s tail Couch – Lovegrass – Purslane Grassland and Herbfield, 12) Darling Pratia – Rat’s tail Couch – Spike Rush Herbfield, 13) Canegrass Grassland, 14) Glinus – Groundsel – Lignum Herbfield, 15) Poplar Box – Mulga – Coolibah Woodland and 16) Black Box Woodland. In total 355 vascular plant taxa were found of which 6% were considered exotic in origin. A population of Dentella minutissima; a species listed as threatened (endangered) under the New South Wales Threatened Species Conservation Act 1995 was found. A summary of select structural and habitat attributes within Alliances is also presented.