Farm revegetation has substantial potential to improve biodiversity outcomes.

Agricultural expansion and intensification has caused habitat loss, contributing to the current biodiversity crisis. Reliable, efficient and consistent information at the farm-scale is critical to understand the magnitude of recent changes in biodiversity and to inform future management actions aimed at reversing historical declines. We apply a habitat-based biodiversity assessment approach to examine the potential for grazing farms across Australia to improve outcomes for biodiversity by revegetating 10 % of the farm area.

Genetic Variation in Flowering Traits of Tasmanian and Association with Provenance Home Site Climatic Factors.

is emerging as an economically important plant for the commercial production of mānuka honey and essential oils, both exhibiting unique antibacterial attributes. To support its domestication this is the first quantitative genetic study of variation for traits. It utilised plants from 200 open-pollinated families derived from 40 native populations, from across the species range in Tasmania, grown in a common garden field trial.

Trees on farms to support natural capital: An evidence-based review for grazed dairy systems.

Intensification of the dairy industry globally, combined with a changing climate, has placed increased pressure on natural capital assets (and the flow of ecosystem services) on farms. Agroforestry is widely promoted as an intervention to address these issues. While some benefits of integrating trees on farms, such as carbon sequestration and biodiversity, are reasonably well known, less is known about other potential benefits, such as on-farm production.

Responses of riparian forests to flood irrigation in the hyper-arid zone of NW China.

Knowledge of forest water use is crucial to water resources managers, especially in arid environments. Flood irrigation has sometimes been used to ameliorate forest decline, however, there has only been limited research on vegetation responses to these interventions. We undertook a study to quantify evapotranspiration (ET) and its components, transpiration (T) and evaporation (E), of two Populus euphratica Oliv.

Elevated CO did not affect the hydrological balance of a mature native Eucalyptus woodland.

Elevated atmospheric CO concentration (eC ) might reduce forest water-use, due to decreased transpiration, following partial stomatal closure, thus enhancing water-use efficiency and productivity at low water availability. If evapotranspiration (E ) is reduced, it may subsequently increase soil water storage (ΔS) or surface runoff (R) and drainage (D ), although these could be offset or even reversed by changes in vegetation structure, mainly increased leaf area index (L). To understand the effect of eC in a water-limited ecosystem, we tested whether 2 years of eC (~40% increase) affected the hydrological partitioning in a mature water-limited Eucalyptus woodland exposed to Free-Air CO Enrichment (FACE).

A multi-species synthesis of physiological mechanisms in drought-induced tree mortality.

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 uncertainty requires improved mortality projections founded on robust physiological processes.

An ecoclimatic framework for evaluating the resilience of vegetation to water deficit.

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 ecoclimatic 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 ecosystem processes. This ecoclimatic framework is underpinned by two hypotheses: (i) exposure to water deficit can be represented probabilistically and used to estimate exposure thresholds across different vegetation types or ecosystems; and (ii) the cumulative impact of a series of water deficit events is defined by attributes governing the resistance and recovery of the affected processes.

Drought responses of two gymnosperm species with contrasting stomatal regulation strategies under elevated [CO2] and temperature.

Future climate regimes characterized by rising [CO2], rising temperatures and associated droughts may differentially affect tree growth and physiology. However, the interactive effects of these three factors are complex because elevated [CO2] and elevated temperature may generate differential physiological responses during drought. To date, the interactive effects of elevated [CO2] and elevated temperature on drought-induced tree mortality remain poorly understood in gymnosperm species that differ in stomatal regulation strategies.

When trends intersect: The challenge of protecting freshwater ecosystems under multiple land use and hydrological intensification scenarios.

Intensification of the use of natural resources is a world-wide trend driven by the increasing demand for water, food, fibre, minerals and energy. These demands are the result of a rising world population, increasing wealth and greater global focus on economic growth. Land use intensification, together with climate change, is also driving intensification of the global hydrological cycle.

Exposure of trees to drought-induced die-off is defined by a common climatic threshold across different vegetation types.

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 associated with documented tree die-off events across Australia using standardized climatic indices to represent the key dimensions of drought stress for a range of vegetation types.

Elevated [CO2] does not ameliorate the negative effects of elevated temperature on drought-induced mortality in Eucalyptus radiata seedlings.

It has been reported that elevated temperature accelerates the time-to-mortality in plants exposed to prolonged drought, while elevated [CO(2)] acts as a mitigating factor because it can reduce stomatal conductance and thereby reduce water loss. We examined the interactive effects of elevated [CO(2)] and temperature on the inter-dependent carbon and hydraulic characteristics associated with drought-induced mortality in Eucalyptus radiata seedlings grown in two [CO(2)] (400 and 640 μL L(-1)) and two temperature (ambient and ambient +4 °C) treatments. Seedlings were exposed to two controlled drying and rewatering cycles, and then water was withheld until plants died.

Carbon dynamics of eucalypt seedlings exposed to progressive drought in elevated [CO2] and elevated temperature.

Elevated [CO2] and temperature may alter the drought responses of tree seedling growth, photosynthesis, respiration and total non-structural carbohydrate (TNC) status depending on drought intensity and duration. Few studies have addressed these important climatic interactions or their consequences. We grew Eucalyptus globulus Labill.

Whole-plant versus leaf-level regulation of photosynthetic responses after partial defoliation in Eucalyptus globulus saplings.

Increases in photosynthetic capacity (A1500) after defoliation have been attributed to changes in leaf-level biochemistry, water, and/or nutrient status. The hypothesis that transient photosynthetic responses to partial defoliation are regulated by whole-plant (e.g.

Drought response strategies define the relative contributions of hydraulic dysfunction and carbohydrate depletion during tree mortality.

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 depletion during mortality. We compared patterns in growth rate, water relations, gas exchange and carbohydrate dynamics in three tree species subjected to prolonged drought.

Ecophysiological responses of a young blue gum (Eucalyptus globulus) plantation to weed control.

Early weed control may improve the growth of forest plantations by influencing soil water and nutrient availability. To understand eucalypt growth responses to weed control, we examined the temporal responses of leaf gas-exchange, leaf nitrogen concentration (N) and water status of 7-month-old Eucalyptus globulus L. trees in a paired-plot field trial.

Canopy processes in a changing climate.

Forest canopies exchange a large part of the mass and energy between the earth and the atmosphere. The processes that regulate these exchanges have been of interest to scientists from a diverse range of disciplines for a long time. The International Union of Forest Research Organizations (IUFRO) Canopy Processes Working Group provides a forum for these scientists to explore canopy processes at scales ranging from the leaf to the ecosystem.

Role of corticular photosynthesis following defoliation in Eucalyptus globulus.

Defoliation can reduce net fixation of atmospheric CO(2) by the canopy, but increase the intensity and duration of photosynthetically active radiation on stems. Stem CO(2) flux and leaf gas exchange in young Eucalyptus globulus seedlings were measured to assess the impact of defoliation on these processes and to determine the potential contribution of re-fixation by photosynthetic inner bark in offsetting the effects of defoliation in a woody species. Pot and field trials examined how artificial defoliation of the canopy affected the photosynthetic characteristics of main stems of young Eucalyptus globulus seedlings.

Daily patterns of stem size variation in irrigated and unirrigated Eucalyptus globulus.

High resolution measurements of stem diameter variation provide a means to study short-term dynamics of tree growth and water status. In this 14-month study, daily changes in stem radius of Eucalyptus globulus Labill. seedlings were measured with electronic point dendrometers in a plantation in southern Tasmania, Australia.

Linking leaf and tree water use with an individual-tree model.

We tested the ability of a model to scale gas exchange from leaf level to whole-tree level by: (1) measuring leaf gas exchange in the canopy of 10 trees in a tall Eucalyptus delegatensis RT Baker forest in NSW, Australia; (2) monitoring sap flow of the same 10 trees during the measurement week; and (3) using an individual-tree-based model (MAESTRA) to link the two sets of measurements. Photosynthesis and stomatal conductance components of the model were parameterized with the leaf gas exchange data, and canopy structure was parameterized with crown heights, dimensions and leaf areas of each of the measurement trees and up to 45 neighboring trees. Transpiration of the measurement trees was predicted by the model and compared with sap flow data.