Why focus on vegetation?
Australia’s floodplains, wetlands and riverine ecosystems are characterised by unique, diverse and often iconic vegetation. From ancient River red gum forests fringing wide lazy rivers, to sedges and grasses emerging from open wetlands, vegetation shapes our landscapes and provides a range of ecological, cultural and economic services.
For tens of thousands of years, Australia’s Aboriginal people used the incredible diversity of floodplain and wetland plants to provide themselves with food, shelter, fibre and medicines. We see echoes of their presence in the scar trees that dot the banks of our inland rivers. European settlers were similarly drawn to our rivers, their floodplains and wetlands for the resources they provided.
The combination of land-clearing, grazing and water use have fundamentally changed the nature and condition of the vegetation across our rivers, floodplains and wetlands. There has been widespread loss of vegetation and, what remains is often in poor condition. One of the main causes of the decline has been changes to the frequency, duration and timing of the water received by a wide variety of vegetation communities. Water for the environment is used throughout the Murray-Darling Basin to support the diversity and condition of vegetation – both woody (trees) and non-woody (groundcover) vegetation including a wide range of shrubs from Tangled lignum to floating ferns such as Azolla. The use of water for the environment to achieve outcomes needs to be underpinned by the best available science.
The Vegetation Theme will evaluate the outcomes from using Commonwealth environmental water to support the diversity and condition of non-woody vegetation. Our evaluation is part of the adaptive management framework that enables us to learn from using water for the environment and contributes to long term improvements in the way water is used. We will conduct research that will improve our ability to evaluate and predict the responses across the Murray-Darling Basin from using Commonwealth environmental water for vegetation outcomes – both woody (trees) and non-woody (groundcover).
Overall, our work will contribute to enduring change by informing the efficient and strategic use of water for the environmental outcomes in the Basin.
Evaluation across six Selected Areas
Under the LTIM program, vegetation data have been collected across six Selected Areas within the Murray-Darling Basin. This data will continue to be collected over the duration of Flow-MER, with the inclusion of a seventh Selected Area. We will use these data to describe vegetation diversity responses to Commonwealth environmental water in both the short (<1year) and longer (1-7years) term. We will focus on species richness (the number of plant species present) and cover (the density of the species) across a variety of vegetation communities.
We have learnt from the LTIM and EWKR programs that the non-woody vegetation that occurs across the riparian, floodplain and wetland areas of the Basin is diverse and highly variable. More than 600 species have been recorded over the past 5 years and many species are confined to distinct places within the Basin at specific times. We now know that Commonwealth water can be used strategically to produce improvements in species richness and cover, as well as producing a greater abundance of native wetland plant species and reduce the cover of exotic plant species. This knowledge will be used to help us understand patterns that will enable us to predict outcomes in places where monitoring is not undertaken.
Extending existing research
The research component of the Vegetation Theme will build on the research undertaken in the EWKR Program, as well as other existing projects, to improve our ability to evaluate outcomes at a Basin-scale, and to determine what drives sustainable populations and diverse communities of water-dependent vegetation in the Murray-Darling Basin.
We will be focusing our efforts in two areas:
Project V1: Benchmarks for non-woody vegetation
This research aims to develop a framework of hierarchical condition benchmarks as well as a process for evaluating success of outcomes for non-woody vegetation at a Basin-scale. This research will benefit environmental water managers by providing:
- a framework for evaluating success of outcomes for non-woody vegetation.
- improved potential to extrapolate outcomes to unmonitored areas.
- a guide for developing objectives and targets.
Project V2: Remote sensing trends and temporal responses of woody vegetation to environmental water.
Maintaining the extent and condition of woody floodplain vegetation, such as River red gum, Black box, Coolibah and Lignum, are key objectives within the Basin Wide Environmental Watering Strategy. Methods are required to remotely assess and interpret data relating to the condition of woody vegetation populations to support Basin-scale prioritisation of where environmental water needs to be delivered, as well as evaluating the outcomes from watering actions.
This research project will focus on determining critical thresholds of water use and vegetation response that will:
- provide Basin-scale assessment of the influence of Commonwealth water with data available every 8 days from 2001.
- determine relationships between vegetation response and water regimes/inundation extent across multiple scales.
- inform local and Basin-scale prioritisation of environmental water for woody vegetation outcomes.
- quantify the links between vegetation change and hydrology, harnessing remotely sensed inundation mapping in collaboration with the hydrology team.
Evaluating the response of non-woody vegetation to Commonwealth environmental water
Non-woody vegetation field data collected by monitoring and evaluation teams at the Selected Areas will be analysed to evaluate the effects of Commonwealth environmental water on the diversity of plants and vegetation communities with respect to:
- species level responses of individual plant species across Selected Areas, including changes to species presence, distribution and abundance.
- community level responses of particular vegetation communities within specific habitat types (e.g. Australian National Aquatic Ecosystem vegetation types) across Selected Areas, including changes in species richness, composition and structure.
- landscape level responses of vegetation communities across the Selected Areas, including changes in the presence, distribution and diversity of particular vegetation communities.
Benchmarks for non-woody vegetation
This research project is being undertaken by Cherie Campbell as a PhD project at the University of Canberra.
This research project aims to address the following questions:
- how can we improve the evaluation of outcomes for non-woody vegetation at a Basin-scale?
- can we develop benchmarks against which to evaluate outcomes for non-woody vegetation?
- can we extrapolate outcomes to unmonitored areas?
These questions will be addressed by reviewing literature, through expert elicitation and by modelling relationships using existing data (both qualitatively and quantitatively).
Remote sensing trends and temporal responses of woody vegetation to environmental water
This research project aims to investigate:
- what existing remotely sensed models tell us about the previous and current condition of long-lived woody floodplain vegetation at regional and Basin-scales.
- translation of remotely sensed evapotranspiration into a Basin-wide condition / response metric and identification of key thresholds.
- how vegetation condition / response trends are related to hydrology across scales including Basin-scale.
- determination of condition of long-lived woody floodplain vegetation prior to the involvement of Commonwealth environmental water.
- the influence of environmental water on woody vegetation condition / response.
- use of remotely sensed tools to inform water management and underpin intervention decisions.
- how tree biomass and carbon link to integration across the Themes.
Dr Tanya Doody is a CSIRO Principal Research Scientist specialising in ecohydrology with a focus on field measurement of tree water use to understand vegetation water requirements and the links between water availability and vegetation condition. Tanya leads the Flow MER vegetation Theme as well as a research project that will enable scaling of floodplain tree water use and hence condition, across the Murray-Darling Basin using remote sensing.
Cherie Campbell is a vegetation ecologist interested in the maintenance and recovery of wetland and floodplain vegetation in river-floodplain ecosystems. Cherie leads a research project that will develop a framework of condition benchmarks and a process for evaluating outcomes for non-woody wetland and floodplain vegetation at a Basin-scale.
Fiona Dyer is a freshwater scientist interested in understanding the way freshwater systems respond to natural and man-made variations in flow so that she can inform decision making in water resource management. Fiona leads the evaluation of the outcomes from using environmental water to support the diversity and condition of non-woody vegetation.
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