ORCID Profile
0000-0002-1645-8775
Current Organisation
NSW Department of Planning, Industry and Environment
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: Wiley
Date: 11-09-2017
Publisher: Wiley
Date: 29-11-2007
DOI: 10.1111/J.1469-8137.2006.01938.X
Abstract: Mangrove trees dominate coastal vegetation in tropical regions, but are completely replaced by herbaceous salt marshes at latitudes above 32 degrees N and 40 degrees S. Because water deficit can increase damage caused by freezing, we hypothesized that mangroves, which experience large deficits as a result of saline substrates, would suffer freeze-induced xylem failure. Vulnerability to freeze-induced xylem embolism was examined in the most poleward mangrove species in North America, in an area where freezing is rare but severe, and in Australia, in an area where freezing is frequent but mild. Percentage loss in hydraulic conductivity was measured following manipulations of xylem tension xylem sap ion concentration was determined using X-ray microanalysis. Species with wider vessels suffered 60-100% loss of hydraulic conductivity after freezing and thawing under tension, while species with narrower vessels lost as little as 13-40% of conductivity. These results indicate that freeze-induced embolism may play a role in setting the latitudinal limits of distribution in mangroves, either through massive embolism following freezing, or through constraints on water transport as a result of vessel size.
Publisher: Oxford University Press (OUP)
Date: 04-03-2015
DOI: 10.1111/BOJ.12260
Publisher: Wiley
Date: 31-05-2011
DOI: 10.1111/J.1469-8137.2011.03772.X
Abstract: Hydraulic traits were studied in temperate, woody evergreens in a high-elevation heath community to test for trade-offs between the delivery of water to canopies at rates sufficient to sustain photosynthesis and protection against disruption to vascular transport caused by freeze-thaw-induced embolism. Freeze-thaw-induced loss in hydraulic conductivity was studied in relation to xylem anatomy, leaf- and sapwood-specific hydraulic conductivity and gas exchange characteristics of leaves. We found evidence that a trade-off between xylem transport capacity and safety from freeze-thaw-induced embolism affects photosynthetic activity in overwintering evergreens. The mean hydraulically weighted xylem vessel diameter and sapwood-specific conductivity correlated with susceptibility to freeze-thaw-induced embolism. There was also a strong correlation of hydraulic supply and demand across species interspecific differences in stomatal conductance and CO(2) assimilation rates were correlated linearly with sapwood- and leaf-specific hydraulic conductivity. Xylem vessel anatomy mediated an apparent trade-off between resistance to freeze-thaw-induced embolism and hydraulic and photosynthetic capacity during the winter. These results point to a new role for xylem functional traits in determining the degree to which species can maintain photosynthetic carbon gain despite freezing events and cold winter temperatures.
Publisher: Oxford University Press (OUP)
Date: 15-06-2010
Abstract: Water transport in conifers occurs through single-celled tracheids that are connected to one another via intertracheid pit membranes. These membranes have two components: the porous margo, which allows water to pass through the membrane, and the impermeable torus, which functions to isolate gas-filled tracheids. During drought, tracheids can become air filled and thus hydraulically dysfunctional, a result of air entering through the pit membrane and nucleating cavitation in the water column. What are the hydraulic tradeoffs associated with cavitation resistance at the pit level, and how do they vary within the structural components of the intertracheid pit? To address these questions, we examined pit structure in 15 species of Cupressaceae exhibiting a broad range of cavitation resistances. Across species, cavitation resistance was most closely correlated to the ratio of the torus to pit aperture diameter but did not vary systematically with margo porosity. Furthermore, our data indicate that constraints on pit hydraulic efficiency are shared: the pit aperture limits pit conductivity in more drought-resistant taxa, while increased margo resistance is more likely to control pit conductivity in species that are more vulnerable to cavitation. These results are coupled with additional data concerning pit membrane structure and function and are discussed in the context of the evolutionary biogeography of the Cupressaceae.
Publisher: Proceedings of the National Academy of Sciences
Date: 20-11-2017
Abstract: The Cupressaceae clade has the broadest ersity in habitat and morphology of any conifer family. This clade is characterized by highly ergent physiological strategies, with deciduous sw -adapted genera-like Taxodium at one extreme, and evergreen desert genera-like Cupressus at the other. The size disparity within the Cupressaceae is equally impressive, with members ranging from 5-m-tall juniper shrubs to 100-m-tall redwood trees. Phylogenetic studies demonstrate that despite this variation, these taxa all share a single common ancestor by extension, they also share a common ancestral habitat. Here, we use a common-garden approach to compare xylem and leaf-level physiology in this family. We then apply comparative phylogenetic methods to infer how Cenozoic climatic change shaped the morphological and physiological differences between modern-day members of the Cupressaceae. Our data show that drought-resistant crown clades (the Cupressoid and Callitroid clades) most likely evolved from drought-intolerant Mesozoic ancestors, and that this pattern is consistent with proposed shifts in post-Eocene paleoclimates. We also provide evidence that within the Cupressaceae, the evolution of drought-resistant xylem is coupled to increased carbon investment in xylem tissue, reduced xylem transport efficiency, and at the leaf level, reduced photosynthetic capacity. Phylogenetically based analyses suggest that the ancestors of the Cupressaceae were dependent upon moist habitats, and that drought-resistant physiology developed along with increasing habitat aridity from the Oligocene onward. We conclude that the modern biogeography of the Cupressaceae conifers was shaped in large part by their capacity to adapt to drought.
Publisher: Wiley
Date: 28-03-2023
Abstract: Budgeting for bio ersity conservation requires realistic estimates of threat abatement costs. However, data on threat management costs are often unavailable or unable to be extrapolated across relevant locations and scales. Conservation expenditure largely occurs without a priori cost estimates of management activities and is not recorded in ways that can inform future budgets or cost‐effective management decisions. We provided transparent, broadly applicable cost models for 18 Threat Abatement Strategies aimed at managing the processes threatening Australia's bio ersity. We defined the actions required to implement each strategy and used a consistent structure to classify costs of labour, travel, consumables and equipment. We drew upon expert knowledge and published literature to parameterise each model, estimating the implementation cost of each strategy across the Australian continent, accounting for spatial variables such as threat presence, terrain, and travel distance. Estimated annualised costs for the threat abatement strategies varied considerably between strategies and across Australia, ranging from $24 to $879,985 per km 2 ($0.24–$8880 per ha). On average, labour was the largest cost component (49%), followed by consumables (37%), travel (13%) and equipment (2%). Based on national scale variables and assumptions, cost estimates across Australia for each threat abatement strategy ranged from +44% and −33% of the most common cost estimate. Policy implications . We provide a consistent and transparent approach to budgeting for threat abatement strategies, aiming to improve conservation planning processes, outcomes, and reporting across Australia. In addition, understanding the budget required to achieve threat management outcomes can aid revenue‐raising and target setting. The models, cost layers and estimates we generate provide the basis for a nationally consistent approach for estimating and recording the cost of bio ersity management strategies, which should be continually updated and improved with local‐scale information over time.
Publisher: Wiley
Date: 11-11-2009
Location: United States of America
Location: Australia
Start Date: 2013
End Date: 2015
Funder: Directorate for Biological Sciences
View Funded ActivityStart Date: 2010
End Date: 2013
Funder: Directorate for Biological Sciences
View Funded Activity