A standardised approach to calculating floodplain tree condition to support environmental watering decisions

Wallace, Todd; Gehrig, Susan; Doody, Tanya M.

doi:10.1007/s11273-020-09716-1

Cited by 8 publications

(16 citation statements)

References 42 publications

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“…Each tree was semipermanently labelled to facilitate repeat assessment. In situ tree crown condition was collected using TLM tree condition method (Souter et al, 2010), and data were interpreted as per Wallace, Gehrig, et al (2020). In brief, crown extent (CE), percentage of existing branches with live leaves and crown density (CD) and percentage of skylight blocked by live crown (Souter et al, 2010) were visually assessed.…”

Section: Methodsmentioning

confidence: 99%

“…In brief, crown extent (CE), percentage of existing branches with live leaves and crown density (CD) and percentage of skylight blocked by live crown (Souter et al, 2010) were visually assessed. TCI was calculated by placing CE and CD data into categories ranging from 0 to 7 and CE and CD category scores to generate a TCI within a range of 0–14 (Wallace, Gehrig, et al, 2020).…”

Section: Methodsmentioning

confidence: 99%

“…Wallace, Gehrig, and Doody (2020) present a pragmatic reporting, communication and decision support tool for the use of data derived from standardised visual assessments of tree crown condition that meets the needs of floodplain managers. The approach, termed the Tree Condition Index (TCI), relies on visual assessment of prevailing condition and trajectory, relative to a predefined measurable statement of desired condition (an ecological target) and a threshold (a condition point) that indicates a need for management action(s) to determine watering priority.…”

Section: Introductionmentioning

confidence: 99%

“…A key strength of the decision support tool presented by Wallace, Gehrig, et al (2020) is its simplicity and low cost, using a simple data collection method (Souter et al, 2010) that is already in wide spread use. This method enables the assessment of large numbers of diverse sites and can provide a transparent and repeatable prioritisation of sites.…”

Section: Introductionmentioning

confidence: 99%

“…This method enables the assessment of large numbers of diverse sites and can provide a transparent and repeatable prioritisation of sites. However, the decision support tool relies on a single line of evidence and is based on the assumption that tree crown extent/density reflects tree accessible soil water stores (Wallace, Gehrig, et al, 2020). While this assumption is likely to be robust at each end of the water availability gradient (e.g.…”

Section: Introductionmentioning

confidence: 99%

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A multiple‐lines‐of‐evidence approach for prioritising environmental watering of wetland and floodplain trees

Wallace

Gehrig²,

Doody

et al. 2021

Ecohydrology

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Long‐lived vegetation is a key attribute of lowland river floodplains; yet dieback is increasingly being reported globally, with prior studies identifying salinity, drought and altered flow regimes as key stressors. In the Murray–Darling Basin (Australia), many floodplain/wetland areas have management strategies that aim to maintain the condition of floodplain tree communities. Environmental water delivery is a key tool used to achieve such outcomes. Currently, one of the primary tools for determining the need for environmental water delivery is a qualitative visual assessment of tree crown condition. To advance to more quantitative assessment and understanding of tree condition, we present a suite of techniques ranging from low‐cost, rapid visual assessment of tree crown condition to laboratory analysis of components of soil condition and in situ measurement of tree physiology. The aim is to address a number of key knowledge gaps on how to use the linkages between soil water availability ↔ tree physiology ↔ tree visual condition to quantitatively inform environmental water delivery decisions to meet management objectives. We have developed a multiple‐lines‐of‐evidence management assessment framework that presents a pathway to enable managers to improve prioritisation management actions. Furthermore, increased confidence in predicted outcomes should assist water holders and floodplain managers to optimise timing and maximise the benefits of environmental watering. Application of outcomes of this research will increase the efficiency of environmental water use.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

A multiple‐lines‐of‐evidence approach for prioritising environmental watering of wetland and floodplain trees

Wallace

Gehrig²,

Doody

et al. 2021

Ecohydrology

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Determining water requirements for Black Box (Eucalyptus largiflorens) floodplain woodlands of high conservation value using drip‐irrigation

Doody

Gehrig

Vervoort

et al. 2021

Hydrological Processes

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Black Box (Eucalyptus largiflorens F. Muell.), is a keystone tree species of lowland semi-arid floodplain ecosystems in south-eastern Australia. E. largiflorens woodlands are of high conservation value and threatened by climate change-induced drought and irrigation water diversions due to their location on upper floodplain areas where flood frequency has declined. Water requirements of E. largiflorens have not been well quantified using empirical data. Accordingly, knowledge gaps exist in relation to volumes of environmental water required to maintain and improve ecological condition for disconnected floodplain woodlands. To further assist conservation and water resource management, we tested the use of drip irrigation to provide a variety of water regimes to experimental plots in order to monitor tree responses. Water was provided via irrigation delivery across four regimes representing known volumes of water, referred to as an environmental water provision, applied over a 22-week period for two Austral summers. Benefits to trees were identified by measuring transpiration and plant water status using sap flow sensors and a Scholander pressure chamber, respectively. Results indicate that volumes of 0.3, 0.4, 0.7 and 0.8 ML increased transpiration and improved plant water status in comparison to a control, with delivery recommended to commence early autumn. Greater volumes (1.4 ML), substantially increased transpiration and improved water status, especially when delivered at a rate of $25 mm week À1 compared to a monthly 'burst' which broadly represented natural, sporadic summer rainfall in the region. For an environmental watering provision of 25 mm week À1 , $178 ha of E. largiflorens woodland can be watered with a 1 GL environmental water allocation. The study methods presented are relevant worldwide and our results further the collective understanding of the benefits environmental water provides to E. largiflorens.

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Constraining organic matter composition and dynamics as a dominant driver of hypoxic blackwater risk during river Murray floodplain inundation

Gibbs

Wallace

Mosley

2022

Hydrological Processes

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The ecology of floodplain ecosystems evolved according to the historical frequency and extent of inundation. In many dryland rivers, inundation frequency has reduced due to regulation, competition for water resources and climate change. In some rivers infrastructure has been constructed to enable temporary rises in water level and more frequent floodplain inundation, delivering environmental water to ecosystems that are dependent on surface water. During such events, the release of dissolved organic carbon (DOC) from inundated plant material may result in depletion of dissolved oxygen (DO). If the rate of DO depletion exceeds re‐aeration, hypoxic conditions can occur. Models have been developed to represent these processes, however, there is a wide range of chemical and biological interactions, and hence model parameters, involved. The aim of this research was: (1) identify the dominant parameters through sensitivity analysis, (2) design and implement a field monitoring program to quantify the inherent variability in those parameters, and (3) translate that input variability into the modelled DO, ultimately to support risk management decisions when planning delivery of environmental water. The results indicated that the mass of organic matter on a floodplain had the greatest impact on the modelled DO concentrations. Based on the field monitoring results, the steady state load of organic matter, that is, when the accumulation and decay rates are equal, was estimated, and vegetation mapping used to apply the field monitoring results across the floodplain for a 206 km reach of river of the River Murray, Australia. The model results from multiple, cumulative, operations identified one particular high‐risk operational site. The results are useful to prioritize monitoring effort to focus on the most sensitive model parameters and indicate that the likelihood of hypoxic conditions can be reduced through slower rates of inundation and timing events to coincide with periods with lower water temperature. The methodology developed can be transferred to other sites where hypoxic conditions are a potential outcome associated with delivery of environmental water.

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A standardised approach to calculating floodplain tree condition to support environmental watering decisions

Cited by 8 publications

References 42 publications

A multiple‐lines‐of‐evidence approach for prioritising environmental watering of wetland and floodplain trees

A multiple‐lines‐of‐evidence approach for prioritising environmental watering of wetland and floodplain trees

Determining water requirements for Black Box (Eucalyptus largiflorens) floodplain woodlands of high conservation value using drip‐irrigation

Constraining organic matter composition and dynamics as a dominant driver of hypoxic blackwater risk during river Murray floodplain inundation

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