Transformations of catchment nutrients in southeast Queensland. Human activity in catchments throughout southeast Queensland has increased nutrient loads in receiving waters. However, until recently there has been a lack of accurate quantification of these loads, and little understanding of their role in stimulating algal blooms. This proposal will examine the links between catchment nutrient inputs to waterways, their transformations and effects on stimulating algal growth in freshwater systems ....Transformations of catchment nutrients in southeast Queensland. Human activity in catchments throughout southeast Queensland has increased nutrient loads in receiving waters. However, until recently there has been a lack of accurate quantification of these loads, and little understanding of their role in stimulating algal blooms. This proposal will examine the links between catchment nutrient inputs to waterways, their transformations and effects on stimulating algal growth in freshwater systems. The outcomes from this research will be information on how catchment nutrients are affecting water quality, thus providing a vehicle for targeting management strategies designed to reduce nutrient loads.Read moreRead less
Turning water into carbon: a synthesis of plant water-use efficiency from leaf to globe. The efficiency with which plants use water to gain carbon is a fundamental aspect of plant growth that has been frequently measured but is poorly understood. Using our new theory to draw together major datasets, the project will make a dramatic advance in our ability to understand and predict this key aspect of ecosystem function.
New approaches for protecting stream health in temperate Australia: Devising nutrient and salinity guidelines using diatoms. Salinity and nutrient enrichment are the most significant forms of water quality degradation in Australian lowland rivers. This project will identify the biological effect of the water quality pollution and develop new methods for its assessment. Most importantly, through the identification of water quality "thresholds" which result in reduced biodiversity, better guidelin ....New approaches for protecting stream health in temperate Australia: Devising nutrient and salinity guidelines using diatoms. Salinity and nutrient enrichment are the most significant forms of water quality degradation in Australian lowland rivers. This project will identify the biological effect of the water quality pollution and develop new methods for its assessment. Most importantly, through the identification of water quality "thresholds" which result in reduced biodiversity, better guidelines for maintaining stream health will be developed.Read moreRead less
Enhancing nutrient retention in soils through management of microbial biomass. Soil microbial-processes are generally studied in relation to mineralisation of nutrients but rarely for their potential to retain nutrients and reduce nutrient leaching. We hypothesise that management of microbial immobilisation will enhance nutrient retention in nutrient enriched soils during seasonal rains. This hypothesis will be tested under strongly seasonal environments of southwest Australia where nutrient lea ....Enhancing nutrient retention in soils through management of microbial biomass. Soil microbial-processes are generally studied in relation to mineralisation of nutrients but rarely for their potential to retain nutrients and reduce nutrient leaching. We hypothesise that management of microbial immobilisation will enhance nutrient retention in nutrient enriched soils during seasonal rains. This hypothesis will be tested under strongly seasonal environments of southwest Australia where nutrient leaching from soils degrades quality of surface and groundwater. We will first investigate pathways and conditions leading to microbial immobilisation. We will then explore the regulation of substrate and nutrient conditions to promote such retention, and subsequently develop management interventions based on microbially-mediated nutrient retention.Read moreRead less
Forestry effects on headwater ecosystem health: a multi-catchment experiment. Most catchments in southern Australia have been logged historically. Increasingly, native forest harvesting occurs in regrowth or drier areas. Although foresters have empirical data on ecological effects of harvesting in pristine or wetter catchments, little exists for drier regrowth areas, hampering effective management to minimize impacts on stream ecosystem health. This project will supply ecological data on stre ....Forestry effects on headwater ecosystem health: a multi-catchment experiment. Most catchments in southern Australia have been logged historically. Increasingly, native forest harvesting occurs in regrowth or drier areas. Although foresters have empirical data on ecological effects of harvesting in pristine or wetter catchments, little exists for drier regrowth areas, hampering effective management to minimize impacts on stream ecosystem health. This project will supply ecological data on stream ecosystems to supplement 4 years of hydrological data collected by Forests NSW from 5 experimental catchments. Results will provide a firmer scientific basis for ecologically sustainable harvesting in this forest type, with flow-on benefits to our national economy, biodiversity, and environment.Read moreRead less
Sediment and seed bank dynamics in river systems of southeastern Australia: Implications for vegetation-based river rehabilitation. Every year in Australia millions of dollars are spent revegetating degraded riparian corridors as part of best practice river rehabilitation. The planting and maintenance of riparian tubestock is an expensive but essential component of current on-the-ground river management across the country. What if the success rate of riparian rehabilitation could be enhanced by ....Sediment and seed bank dynamics in river systems of southeastern Australia: Implications for vegetation-based river rehabilitation. Every year in Australia millions of dollars are spent revegetating degraded riparian corridors as part of best practice river rehabilitation. The planting and maintenance of riparian tubestock is an expensive but essential component of current on-the-ground river management across the country. What if the success rate of riparian rehabilitation could be enhanced by combining geomorphic and ecological knowledge to maximise the germination of native seeds stored in riparian seed banks? As the conservation of biodiversity becomes integral to environmental management, understanding riparian seed bank dynamics and seedling establishment within a geomorphic framework is an essential tool in river rehabilitation practice.Read moreRead less
Sediment-derived scenarios of wetland status and change, the Lower River Murray, SA. River Murray wetlands changed early in European settlement so the pre-impact conditions are invisible to managers relying on anecdote or monitoring. Baseline conditions of wetlands can be derived from ecological archives preserved in sediments. Fossil diatom assemblages, reflective of past water quality, and other fossils, will be exhumed from sediment sequences to reconstruct wetland conditions. The integration ....Sediment-derived scenarios of wetland status and change, the Lower River Murray, SA. River Murray wetlands changed early in European settlement so the pre-impact conditions are invisible to managers relying on anecdote or monitoring. Baseline conditions of wetlands can be derived from ecological archives preserved in sediments. Fossil diatom assemblages, reflective of past water quality, and other fossils, will be exhumed from sediment sequences to reconstruct wetland conditions. The integration of multiple indicators of the past will generate graphic re-enactments of natural wetland dynamics. These will provide a vision for community and government on-ground managers enabling them to perceive appropriate targets for wetland state and so generate measures to work towards sustainable conditions.Read moreRead less
Retrospective ecological character assessment for a review of Ramsar status of The Coorong, SA. Integrated analyses of the chemical and biological remains contained in the sediments of the Coorong will provide for a reconstruction of ecological change and variability over the last several thousand years. Detailed analyses of the recent sediments will measure how the condition of the Coorong has departed from this natural background and so provide an audit of human impact on the last wetland in t ....Retrospective ecological character assessment for a review of Ramsar status of The Coorong, SA. Integrated analyses of the chemical and biological remains contained in the sediments of the Coorong will provide for a reconstruction of ecological change and variability over the last several thousand years. Detailed analyses of the recent sediments will measure how the condition of the Coorong has departed from this natural background and so provide an audit of human impact on the last wetland in the Murray darling Basin. This evidence will directly inform the determination of the ecological character of this Ramsar listed, national ecological asset and steer its management for a sustainable future. Read moreRead less
Testing the Flood Pulse Concept for rivers with variable flow regimes. For floodplain rivers the major unifying conceptual model linking hydrology, biogeochemistry and ecology is the Flood Pulse Concept (FPC). The model is based on rivers that have a seasonally predictable and long duration inundation of floodplain habitats. Recent reviews of the FPC indicate that the model needs to be broadened to describe the function of rivers with more variable flow regimes. This project will test some of th ....Testing the Flood Pulse Concept for rivers with variable flow regimes. For floodplain rivers the major unifying conceptual model linking hydrology, biogeochemistry and ecology is the Flood Pulse Concept (FPC). The model is based on rivers that have a seasonally predictable and long duration inundation of floodplain habitats. Recent reviews of the FPC indicate that the model needs to be broadened to describe the function of rivers with more variable flow regimes. This project will test some of the predictions of the FPC for variable dryland rivers by investigating how food webs in the channels of a floodplain reach respond to flows of different magnitude, seasonal timing and duration.Read moreRead less
Spatial scale of influence of riparian and catchment land use on stream ecosystem health. Human activities at the landscape scale comprise one of the greatest threats to the ecological integrity of river ecosystems. Government and community groups across Australia are making significant efforts in riparian protection and rehabilitation in an attempt to improve the health of degraded waterways but are hampered in their goal to maximise the environmental gains for every dollar or unit effort inve ....Spatial scale of influence of riparian and catchment land use on stream ecosystem health. Human activities at the landscape scale comprise one of the greatest threats to the ecological integrity of river ecosystems. Government and community groups across Australia are making significant efforts in riparian protection and rehabilitation in an attempt to improve the health of degraded waterways but are hampered in their goal to maximise the environmental gains for every dollar or unit effort invested. The proposed research on understanding the spatial scale of influence of land use and the aggregative effects on stream ecosystems will provide a robust framework to assess various options and optimise benefits from management actions. Read moreRead less