Patrick Mitchell

Patrick Mitchell
The Commonwealth Scientific and Industrial Research Organisation | CSIRO · Land and Water Flagship

30.66
 · 
Doctor of Philosophy

About

57
Publications
22,008
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
3,211
Citations
Research Experience
July 2008 - August 2010
University of Melbourne
Position
  • PostDoc Position
January 2006 - July 2008
University of Western Australia
Position
  • Research Associate
Education
March 2004 - September 2009
University of Western Australia
Field of study
  • Plant Biology

Publications

Publications (57)
Conference Paper
Full-text available
Extensive ruminant livestock production is complex, and it is difficult and time-consuming to obtain quantitative information for decision making (e.g. biomass and quality of forage). Increasingly data from historic records, seasonal forecasts, or near real-time data from remote or on-farm sensors. However, there is limited capacity to compile, int...
Article
Full-text available
Key message Comparing juvenile and adult shoots of Eucalyptus globulus reveals that juvenile leaves are more vulnerable to hydraulic failure than adults while stems show no significant differences. Abstract Understanding variation in the susceptibility for xylem tissue to cavitate and lose its function during water stress exposure is critical for...
Article
Extreme disturbance events, such as wildfire and drought, have large impacts on carbon storage and sequestration of forests and woodlands globally. Here, we present a modelling approach that assesses the relative impact of disturbances on carbon storage and sequestration, and how this will alter under climate change. Our case study is semi-arid Aus...
Technical Report
Full-text available
The Bioregional Assessment Programme provides transparent scientific information to better understand the potential impacts of coal seam gas (CSG) and coal mining developments on water resources and water-dependent assets such as wetlands and groundwater bores. A bioregional assessment (BA) is a regional-scale analysis of the ecology, hydrology, ge...
Technical Report
The conceptual model of causal pathways characterises the causal pathways, the logical chains of events ‒ either planned or unplanned ‒ that link coal resource development and potential impacts on water resources and water-dependent assets. This section details the specific application to the Namoi subregion of methods described in the companion su...
Article
Full-text available
Heat waves have profoundly impacted biota globally over the past decade, especially where their ecological impacts are rapid, diverse, and broad-scale. Although usually considered in isolation for either terrestrial or marine ecosystems, heat waves can straddle ecosystems of both types at subcontinental scales, potentially impacting larger areas an...
Article
Reforestation schemes, which encompass environmental plantings and natural regeneration of vegetation on cleared land, are increasingly being established for the purposes of mitigating anthropogenic carbon emissions. However, these schemes are themselves at risk from climate change and associated changes in disturbance regimes. Simultaneously, ther...
Article
Full-text available
In the version of this Perspective originally published, affiliations 1 and 4 ware incorrect, and should have read: “¹Antarctic Climate & Ecosystems CRC, University of Tasmania, Hobart, Tasmania, Australia” and “⁴Centre for Water, Climate and Land (CWCL), University of Newcastle, Callaghan, NSW, Australia”. These have been corrected in the online v...
Article
Full-text available
The interaction of gradual climate trends and extreme weather events since the turn of the century has triggered complex and, in some cases, catastrophic ecological responses around the world. We illustrate this using Australian examples within a press-pulse framework. Despite the Australian biota being adapted to high natural climate variability,...
Article
Full-text available
During the night, plant water loss can occur either through the roots, as hydraulic redistribution (HR), or through the leaves via the stoma, as nocturnal transpiration (En), which was methodologically difficult to separate from stem refilling (Re). While HR and En have been reported across a range of species, ecosystem, and climate zone, there is...
Article
Full-text available
Understanding intraspecific variation in the vulnerability of the xylem to hydraulic failure during drought is critical in predicting the response of forest tree species to climate change. However, few studies have assessed intraspecific variation in this trait, and a likely limitation is the large number of measurements required to generate the st...
Article
Full-text available
Widespread tree mortality associated with drought has been observed on all forested continents and global change is expected to exacerbate vegetation vulnerability. Forest mortality has implications for future biosphere-atmosphere interactions of carbon, water and energy balance, and is poorly represented in dynamic vegetation models. Reducing unce...
Article
Full-text available
Drought can cause major damage to plant communities, but species damage thresholds and postdrought recovery of forest productivity are not yet predictable. We used an El Niño drought event as a natural experiment to test whether postdrought recovery of gas exchange could be predicted by properties of the water transport system, or if metabolism, pr...
Article
Widespread tree mortality associated with drought has been observed on all forested continents and global change is expected to exacerbate vegetation vulnerability. Forest mortality has implications for future biosphere–atmosphere interactions of carbon, water and energy balance, and is poorly represented in dynamic vegetation models. Reducing unce...
Article
The complex regulatory system controlling stomata involves physical and chemical signals that affect guard cell turgor to bring about changes in stomatal conductance (gs). Abscisic acid (ABA) closes stomata, yet the mechanisms controlling foliar ABA status in tree species remain unclear. The importance of foliage-derived ABA in regulating gas excha...
Article
The surge in global efforts to understand the causes and consequences of drought on forest ecosystems has tended to focus on specific impacts such as mortality. We propose an eco-climatic framework that takes a broader view of the ecological relevance of water deficits, linking elements of exposure and resilience to cumulative impacts on a range of...
Article
Full-text available
Tree species are exposed to single and combined forms of stress capable of inducing severe changes in plant functioning and survival. Climate change and other human disturbance continue to introduce novel combinations of stressors in forest ecosystems that make predicting their impact exceedingly difficult. In this chapter, we examine the causes an...
Article
Full-text available
Growth responses to water deficit translate into discernible changes in the structure of woody tissues and provide an integrated record of historical water availability throughout the life of the individual. The highly dynamic nature of woody growth can impart adaptive changes in physiological performance through changes in xylem elements that regu...
Article
Full-text available
The evolution of lignified xylem allowed for the efficient transport of water under tension, but also exposed the vascular network to the risk of gas emboli and the spread of gas between xylem conduits, thus impeding sap transport to the leaves. A well-known hypothesis proposes that the safety of xylem (its ability to resist embolism formation and...
Article
Full-text available
Successful management of forest systems requires a deeper understanding of the role of ecophysiological traits in enabling adaptation to high temperature and water deficit under current and anticipated changes in climate. A key attribute of leaf water relations is the water potential at zero turgor (πtlp), because it defines the operating water pot...
Article
Full-text available
The objective of this study was to estimate the recovery trajectory of evapotranspiration (Et) and streamflow (Q) in resprouting forested catchments following wildfire. Recovery dynamics were assessed in mixed species eucalypt forests in south-eastern Australia which recover from disturbance largely via vegetative resprouting, and to a lesser degre...
Article
Full-text available
Stomatal conductance (gs) is a key land-surface attribute as it links transpiration, the dominant component of global land evapotranspiration, and photosynthesis, the driving force of the global carbon cycle. Despite the pivotal role of gs in predictions of global water and carbon cycle changes, a global-scale database and an associated globally ap...
Chapter
Full-text available
Environmental stress can be viewed as the physical, chemical, and biological con-straints on the productivity and development of ecosystems. For plants, Grime (1977) hypothesized that stress is one of the three fundamental drivers shaping plant strategies and he defined stress as a set of external constraints limiting the rate of resource acquisiti...
Article
Full-text available
Forests which recover from disturbance predominately via vegetative resprouting may be expected to have different catchment water balance dynamics following wildfire than forests recovering from seed. However, the impacts of wildfire on forest water use are largely unknown in resprouting forest types. This is despite their dominance across the majo...
Chapter
Full-text available
Plant life in the kwongan occurs in a Mediterranean environment, with hot dry summers and cool wet winters (Beard, 1976). The sandy soils typically have a low water-holding capacity and tend to be water-repellent, due to the presence of hydrophobic skins of a very stable humic fraction of soil organic matter and plant-derived substances on the sand...
Data
Figure 7 in Chapter 5 of .Plant Life on the Sandplains in Southwest Australia, a Global Biodiversity Hotspot. Lambers, H. (ed.). University of Western Australia Publishing, Crawley, in press. Available in August 2014. Sunken stomata in stomatal crypts of Banksia species with thick leaves, and stomata on the lower leaf surface in Banksia species wit...
Article
Full-text available
Increases in drought and temperature stress in forest and woodland ecosystems are thought to be responsible for the rise in episodic mortality events observed globally. However, key climatic drivers common to mortality events and the impacts of future extreme droughts on tree survival have not been evaluated. Here, we characterize climatic drivers...
Article
Full-text available
Gas exchange, growth, water transport and carbon (C) metabolism diminish during drought according to their respective sensitivities to declining water status. The timing of this sequence of declining physiological functions may determine how water and C relations compromise plant survival. In this paper, we test the hypothesis that the degree of as...
Data
Figure S1. Drought history and details of the 2010–2011 drought event near Jarrahdale in Australia's south west. Figure S2. Comparison of four GCMs and three scenarios for different sites across Australia. Table S1. Details of the 15 documented die-off sites used in this study (sorted by climate wetness; precipitation divided by potential evaporati...
Article
Full-text available
Following disturbance many woody species are capable of resprouting new foliage, resulting in a reduced leaf-to-sapwood area ratio and altered canopy structure. We hypothesized that such changes would promote adjustments in leaf physiology, resulting in higher rates of transpiration per unit leaf area, consistent with the mechanistic framework prop...
Conference Paper
Background/Question/Methods Changes in atmospheric concentration of greenhouse gases are driving changes in the distribution of rainfall and temperature regimes. Warming temperatures and declining rainfall, especially in mid to high latitudes are believed to be important drivers of recent mortality events around the globe. The impacts of these ev...
Article
Plant survival during drought requires adequate hydration in living tissues and carbohydrate reserves for maintenance and recovery. We hypothesized that tree growth and hydraulic strategy determines the intensity and duration of the 'physiological drought', thereby affecting the relative contributions of loss of hydraulic function and carbohydrate...
Article
Full-text available
Shifts in rainfall patterns and increasing temperatures associated with climate change are likely to cause widespread forest decline in regions where droughts are predicted to increase in duration and severity. One primary cause of productivity loss and plant mortality during drought is hydraulic failure. Drought stress creates trapped gas emboli i...
Article
Full-text available
SUMMARY Patterns in forest structure and function are tightly coupled to variation in energy and soil water gradients and disturbance history across the landscape. In eucalypt forests of southern Australia, changes in forest structure may account for the majority of variation in the evapotranspiration (Et) signal across a single forest type. In thi...
Article
Forest water use estimates derived from sap flow measurements in three contrasting regions of south-eastern Australia were compared. In each region, annual evapotranspiration was highly spatially variable, influenced by water availability, potential evapotranspiration, soil depth and texture, groundwater depth and salinity and at one site by specie...
Article
Full-text available
Highlights ► Controls on spatial and temporal variation in forest water budget after drought were quantified. ► Evapotranspiration was consistent between years, driven by evaporative demand and landscape position. ► Soil water deficits decreased stream flow for several years following a severe drought. ► Drought decoupled evapotranspiration and soi...
Article
Fire induced changes to the vegetation dynamics in temperate forests have been demonstrated to affect evapotranspiration (Et) rates through increases in plant size and density and stand-level transpiration and interception. In many cases these transient changes in forest structure result in substantial declines in stream flow for protracted periods...
Article
In semi-arid ecosystems, evapotranspiration (Et) generally represents the greatest flux of water out of an ecosystem and is sensitive to changes in vegetation cover. In southern Australia, removal of native, deep-rooted perennials to make way for annual crops and pastures with shallower roots and less annual transpiration has led to rising, saline...
Article
Full-text available
Assessing the hydrological imbalance and associated land degradation issues facing much of southern Australia and other parts of the world requires a better understanding of the defining features of ecosystem water use and the design of sustainable agroecosystems. Thus, by grouping species with similar water-use strategies into 'hydraulic functiona...
Article
We measured leaf water relations and leaf structural traits of 20 species from three communities growing along a topographical gradient. Our aim was to assess variation in seasonal responses in leaf water status and leaf tissue physiology between sites and among species in response to summer water deficit. Species from a ridge-top heath community s...
Article
Understanding the water relations of Eucalyptus trees plays an important role in finding solutions to dryland salinity in southern Australia. A model for studying structure–function relationships in isolated tree crowns (radiation absorption, transpiration and photosynthesis, RATP) was parameterized to permit the seasonal transpiration course of a...

Projects

Projects (2)
Project
The aim of this project is to examine and quantify fundamental physiological mechanisms underlying broader plant processes and responses, with a particular emphasis on functionally and ecologically diverse plant taxa occurring in temperate ecosystems.
Project
The Australian Government’s Bioregional Assessment Programme provides transparent scientific information to better understand the potential impacts of coal seam gas and coal mining developments on water resources and water-dependent assets such as wetlands and groundwater bores (see http://www.bioregionalassessments.gov.au/)