Showing papers by "Cooperative Research Centre published in 2002"

Soil carbon stocks and land use change: a meta analysis

Abstract: The effects of land use change on soil carbon stocks are of concern in the context of international policy agendas on greenhouse gas emissions mitigation. This paper reviews the literature for the influence of land use changes on soil C stocks and reports the results of a meta analysis of these data from 74 publications. The meta analysis indicates that soil C stocks decline after land use changes from pasture to plantation (−10%), native forest to plantation (−13%), native forest to crop (−42%), and pasture to crop (−59%). Soil C stocks increase after land use changes from native forest to pasture (+ 8%), crop to pasture (+ 19%), crop to plantation (+ 18%), and crop to secondary forest (+ 53%). Wherever one of the land use changes decreased soil C, the reverse process usually increased soil carbon and vice versa. As the quantity of available data is not large and the methodologies used are diverse, the conclusions drawn must be regarded as working hypotheses from which to design future targeted investigations that broaden the database. Within some land use changes there were, however, sufficient examples to explore the role of other factors contributing to the above conclusions. One outcome of the meta analysis, especially worthy of further investigation in the context of carbon sink strategies for greenhouse gas mitigation, is that broadleaf tree plantations placed onto prior native forest or pastures did not affect soil C stocks whereas pine plantations reduced soil C stocks by 12–15%.

Basic principles and ecological consequences of altered flow regimes for aquatic biodiversity.

Abstract: The flow regime is regarded by many aquatic ecologists to be the key driver of river and floodplain wet- land ecosystems. We have focused this literature review around four key principles to highlight the important mech- anisms that link hydrology and aquatic biodiversity and to illustrate the consequent impacts of altered flow regimes: Firstly, flow is a major determinant of physical habitat in streams, which in turn is a major determinant of biotic com- position; Secondly, aquatic species have evolved life history strategies primarily in direct response to the natural flow regimes; Thirdly, maintenance of natural patterns of longitu- dinal and lateral connectivity is essential to the viability of populations of many riverine species; Finally, the invasion and success of exotic and introduced species in rivers is facilitated by the alteration of flow regimes. The impacts of flow change are manifest across broad taxonomic groups including riverine plants, invertebrates, and fish. Despite growing recognition of these relationships, ecologists still struggle to predict and quantify biotic responses to altered flow regimes. One obvious difficulty is the ability to distin- guish the direct effects of modified flow regimes from im- pacts associated with land-use change that often accom- panies water resource development. Currently, evidence about how rivers function in relation to flow regime and the flows that aquatic organisms need exists largely as a series of untested hypotheses. To overcome these problems, aquatic science needs to move quickly into a manipulative or experimental phase, preferably with the aims of restora- tion and measuring ecosystem response.

Does conversion of forest to agricultural land change soil carbon and nitrogen? a review of the literature

Abstract: Soil carbon is a large component of the global carbon cycle and its management can significantly affect the atmospheric CO2 concentration. An important management issue is the extent of soil carbon (C) release when forest is converted to agricultural land. We reviewed the literature to assess changes in soil C upon conversion of forests to agricultural land. Analyses are confounded by changes in soil bulk density upon land-use change, with agricultural soils on average having 13% higher bulk density. Consistent with earlier reviews, we found that conversion of forest to cultivated land led to an average loss of approximately 30% of soil C. When we restricted our analysis to studies that had used appropriate corrections for changes in bulk density, soil C loss was 22%. When, from all the studies compiled, we considered only studies reporting both soil C and nitrogen (N), average losses of C and N were 24% and 15%, respectively, hence showing a decrease in the average C : N ratio. The magnitude of these changes in the C : N ratio did not correlate with either C or N changes. When considering the transition from forest to pasture, there was no significant change in either soil C or N, even though reported changes in soil C ranged from −50% to +160%. Among studies that reported changes in soil N as well as soil C, C : N ratios both increased and decreased, with trends depending on changes in system N. Systems with increasing soil N generally had decreased C : N ratios, whereas systems with decreasing soil N had increased C : N ratios. Our survey confirmed earlier findings that conversion of forest to cropland generally leads to a loss of soil carbon, although the magnitude of change might have been inflated in many studies by the confounding influence of bulk-density changes. In contrast, conversion of forest to uncultivated grazing land did not, on average, lead to loss of soil carbon, although individual sites may lose or gain soil C, depending on specific circumstances, such as application of fertiliser or retention or removal of plant residues.

A recombinant blood-stage malaria vaccine reduces Plasmodium falciparum density and exerts selective pressure on parasite populations in a phase 1-2b trial in Papua New Guinea.

Abstract: The malaria vaccine Combination B comprises recombinant Plasmodium falciparum ring-infected erythrocyte surface antigen and 2 merozoite surface proteins (MSP1 and MSP2) formulated in oil-based adjuvant. A phase 1-2b double-blind, randomized, placebo-controlled trial in 120 children (5-9 years old) in Papua New Guinea demonstrated a 62% (95% confidence limits: 13%, 84%) reduction in parasite density in children not pretreated with sulfadoxine-pyrimethamine. Vaccinees had a lower prevalence of parasites carrying the MSP2-3D7 allelic form (corresponding to that in the vaccine) and a higher incidence of morbid episodes associated with FC27-type parasites. These results demonstrate functional activity of Combination B against P. falciparum in individuals with previous malaria exposure. The specific effects on parasites with particular msp2 genotypes suggest that the MSP2 component, at least in part, accounted for the activity. The vaccine-induced selection pressure exerted on the parasites and its consequences for morbidity strongly argue for developing vaccines comprising conserved antigens and/or multiple components covering all important allelic types.

Association of dwarfism and floral induction with a grape ‘green revolution’ mutation

Abstract: The transition from vegetative to reproductive growth is an essential process in the life cycle of plants. Plant floral induction pathways respond to both environmental and endogenous cues and much has been learnt about these genetic pathways by studying mutants of Arabidopsis1,2. Gibberellins (GAs) are plant growth regulators important in many aspects of plant growth and in Arabidopsis they promote flowering3,4,5. Here we provide genetic evidence that GAs inhibit flowering in grapevine. A grapevine dwarf mutant derived from the L1 cell layer of the champagne cultivar Pinot Meunier produces inflorescences along the length of the shoot where tendrils are normally formed. The mutated gene associated with the phenotype is a homologue of the wheat ‘green revolution’ gene Reduced height-1 (ref. 6) and the Arabidopsis gene GA insensitive (GAI)7. The conversion of tendrils to inflorescences in the mutant demonstrates that the grapevine tendril is a modified inflorescence inhibited from completing floral development by GAs.

Representing biodiversity: data and procedures for identifying priority areas for conservation.

Abstract: Biodiversity priority areas together should represent the biodiversity of the region they are situated in. To achieve this, biodiversity has to be measured, biodiversity goals have to be set and methods for implementing those goals have to be applied. Each of these steps is discussed. Because it is impossible to measure all of biodiversity, biodiversity surrogates have to be used. Examples are taxa sub-sets, species assemblages and environmental domains. Each of these has different strengths and weaknesses, which are described and evaluated. In real-world priority setting, some combination of these is usually employed. While a desirable goal might be to sample all of biodiversity from genotypes to ecosystems, an achievable goal is to represent, at some agreed level, each of the biodiversity features chosen as surrogates. Explicit systematic procedures for implementing such a goal are described. These procedures use complementarity, a measure of the contribution each area in a region makes to the conservation goal, to estimate irreplaceability and flexibility, measures of the extent to which areas can be substituted for one another in order to take competing land uses into account. Persistence and vulnerability, which also play an important role in the priority setting process, are discussed briefly.

T-ray computed tomography.

Abstract: We demonstrate a tomographic imaging modality that uses pulsed terahertz (THz) radiation to probe the optical properties of three-dimensional (3D) structures in the far-infrared. This THz-wave computed tomography (T-ray CT) system provides sectional images of objects in a manner analogous to conventional CT techniques such as x-ray CT. The transmitted amplitude and phase of broadband pulses of THz radiation are measured at multiple projection angles. The filtered backprojection algorithm is then used to reconstruct the target object, including both its 3D structure and its frequency-dependent far-infrared optical properties.

Optical remote sensing applications in viticulture - a review

Abstract: The emergence of precision agriculture technologies and an increasing demand for higher quality grape products have led to a growing interest in the practice of precision viticulture; monitoring and managing spatial variations in productivity-related variables within single vineyard blocks. Potentially, one of the most powerful tools in precision viticulture is the use of remote sensing, which has the ability to rapidly provide a description of grapevine shape, size and vigour over entire vineyards. Its potential for improving viticultural practice will rely on being able to define useful relationships between these canopy descriptors and grape quality and yield. This paper introduces the reader to remote sensing and reviews its recent, and potential, applications in viticulture.

Using ants as bioindicators in land management: simplifying assessment of ant community responses

Abstract: Summary 1. The indicator qualities of terrestrial invertebrates are widely recognized in the context of detecting ecological change associated with human land-use. However, the use of terrestrial invertebrates as bioindicators remains more a topic of scientific discourse than a part of land-management practice, largely because their inordinate numbers, taxonomic challenges and general unfamiliarity make invertebrates too intimidating for most land-management agencies. Terrestrial invertebrates will not be widely adopted as bioindicators in land management until simple and efficient protocols have been developed that meet the needs of land managers. 2. In Australia, ants are one group of terrestrial insects that has been commonly adopted as bioindicators in land management, and this study examined the reliability of a simplified ant assessment protocol designed to be within the capacity of a wide range of land managers. 3. Ants had previously been surveyed intensively as part of a comprehensive assessment of biodiversity responses to SO 2 emissions from a large copper and lead smelter at Mt Isa in the Australian semi-arid tropics. This intensive ant survey yielded 174 species from 24 genera, and revealed seven key patterns of ant community structure and composition in relation to habitat and SO 2 levels. 4. We tested the extent to which a greatly simplified ant assessment was able to reproduce these results. Our simplified assessment was based on ant ‘bycatch’ from bucket-sized (20-litre) pitfall traps used to sample vertebrates as part of the broader biodiversity survey. We also greatly simplified the sorting of ant morphospecies by considering only large (using a threshold of 4 mm) species, and we reduced sorting time by considering only the presence or absence of species at each site. In this manner, the inclusion of ants in the assessment process required less than 10% of the effort demanded by the intensive ant survey. 5. Our simplified protocol reproduced virtually all the key findings of the intensive survey. This puts effective ant monitoring within the capacity of a wide range of land managers.

Sharing the true stories: improving communication between Aboriginal patients and healthcare workers.

Abstract: Objectives: To identify factors limiting the effectiveness of communication between Aboriginal patients with end-stage renal disease and healthcare workers, and to identify strategies for improving communication. Design: Qualitative study, gathering data through (a) videotaped interactions between patients and staff, and (b) in-depth interviews with all participants, in their first language, about their perceptions of the interaction, their interpretation of the video record and their broader experience with intercultural communication. Setting: A satellite dialysis unit in suburban Darwin, Northern Territory. The interactions occurred between March and July 2001. Participants: Aboriginal patients from the Yolngu language group of north-east Arnhem Land and their medical, nursing and allied professional carers. Main outcome measures: Factors influencing the quality of communication. Results: A shared understanding of key concepts was rarely achieved. Miscommunication often went unrecognised. Sources of miscommunication included lack of patient control over the language, timing, content and circumstances of interactions; differing modes of discourse; dominance of biomedical knowledge and marginalisation of Yolngu knowledge; absence of opportunities and resources to construct a body of shared understanding; cultural and linguistic distance; lack of staff training in intercultural communication; and lack of involvement of trained interpreters. Conclusions: Miscommunication is pervasive. Trained interpreters provide only a partial solution. Fundamental change is required for Aboriginal patients to have significant input into the management of their illness. Educational resources are needed to facilitate a shared understanding, not only of renal physiology, disease and treatment, but also of the cultural, social and economic dimensions of the illness

Estimating Average Particle Size by Focused Beam Reflectance Measurement (FBRM)

Abstract: The Lasentec focused beam reflectance measurement (FBRM) probe provides in situ particle characterisation over a wide range of suspension concentrations. This is a significant advantage over conventional instruments that require sampling and dilution. However, FBRM gives a chord distribution, rather than a conventional diameter distribution. Both theoretical and empirical methods for converting from chord to diameter data are available, but the empirical method was found to be more successful. The FBRM response has been compared to conventional particle sizing techniques (laser diffraction and electrical sensing zone) for a range of sieved aluminium or calcite suspensions. The mode average of the square-weighted chord length was found to be comparable to other sizing techniques over the range from 50 to 400 μm. The square-weighted FBRM results were essentially unaffected by changes to the instrument focal position, the suspension fluid flow velocity, or the solid fraction in the range 0.1-20% w/v.

River regulation and fish larvae: variation through space and time

Abstract: 1. Patterns in abundance and distribution of larval fish in a heavily regulated and a mildly regulated Australian lowland river were compared over four breeding seasons to gain some insight into how river regulation affects fish populations. 2. Larvae from a total of 13 species from nine families were recorded from the two rivers. The mildly regulated Broken River supported twice as many species as the heavily regulated Campaspe River. The two rivers shared three introduced species but only two native species. The dominant species in the Campaspe was not found in the Broken River. 3. The two most abundant species in the Campaspe were classified as `opportunists'. They are small, short-lived species, which spawn for up to 9 months, encompassing extremes in temperature and flow. The extended spawning period may place a subset of larvae in optimal conditions for recruitment and is hypothesised as being the key to the success of these species. 4. Most species spawned each year, despite large interannual variation in flow and temperature conditions. Poor recruitment over several decades, rather than a failure to spawn, is considered the most likely explanation for differences in the larval fish faunas between the two rivers. 5. The highly regulated section of the Campaspe River downstream of the regulating impoundment is thought to provide suboptimal habitat conditions for larvae relative to the less regulated downstream sections. 6. The timing of occurrence of larvae of the dominant species varied by breeding season and may be the result of flexibility in the timing of spawning.

Reversible Addition−Fragmentation Chain Transfer Polymerization Initiated with Ultraviolet Radiation

Abstract: Styrene was polymerized under a source of ultraviolet radiation in the presence of certain thiocarbonylthio compounds. Use of 1-phenylethyl phenyldithioacetate (1-PEPDTA) produced well-defined polymers with molecular weights close to those predicted from theory, up to conversions of 30%. The mechanism of polymerization was examined and shown to proceed via reversible addition-fragmentation chain transfer, as opposed to reversible termination with a thiocarbonylthiyl radical. UV-induced decomposition of the dithioester moiety in 1-PEPDTA and 1-phenylethyl dithiobenzoate (1-PEDB) mediated RAFT polymerizations was followed using UV/vis spectrophotometry, 1-PEPDTA decomposed much slower than 1-PEDB. Analysis of the decomposition products of 1-PEPDTA with gas chromatography/mass spectrometry was used to elucidate a possible mechanism for its degradation, suggesting that both 1-phenylethyl and benzyl radicals are decomposition products.

Legitimizing fluvial ecosystems as users of water: An overview

Abstract: We suggest that fluvial ecosystems are legitimate users of water and that there are basic ecological principles guiding the maintenance of long-term ecological vitality. This article articulates some fundamental relationships between physical and ecological processes, presents basic principles for maintaining the vitality of fluvial ecosystems, identifies several major scientific challenges and opportunities for effective implementation of the basic ecological principles, and acts as an introduction to three specific articles to follow on biodiversity, biogeochemistry, and riparian communities. All the objectives, by necessity, link climate, land, and fresh water. The basic principles proposed are: (1) the natural flow regime shapes the evolution of aquatic biota and ecological processes, (2) every river has a characteristic flow regime and an associated biotic community, and (3) aquatic ecosystems are topographically unique in occupying the lowest position in the landscape, thereby integrating catchment-scale processes. Scientific challenges for the immediate future relate to quantifying cumulative effects, linking multidisciplinary knowledge and models, and formulating effective monitoring and assessment procedures. Additionally, forecasting the ecological consequences of changing water regimes is a fundamental challenge for science, especially as environmental issues related to fresh waters escalate in the next two to three decades.

The neuro-m method for fitting neural network parametric pedotransfer functions

Abstract: Parametric pedotransfer functions (PTFs), which predict parameters of a model from basic soil properties are useful in deriving continuous functions of soil properties, such as water retention curves. The common method for deriving parametric water retention PTFs involves estimating the parameters of a soil hydraulic model by fitting the model to the data, and then forming empirical relationships between basic soil properties and parameters. The latter step usually utilizes multiple linear regression or artificial neural networks. Neural network analysis is a powerful tool and has been shown to perform better than multiple linear regression. However neural-network PTFs are usually trained with an objective function that fits the estimated parameters of a soil hydraulic model. We called this the neuro-p method. The estimated parameters may carry errors and since the aim is to be able to estimate water retention, it is sensible to train the network to fit the measured water content. We propose a new objective function for neural network training, which predicts the parameters of the soil hydraulic model and optimizes the PTF to match the measured and observed water content, we called this neuro-m method. This method was used to predict the parameters of the van Genuchten model. Using Australian soil hydraulic data as a training set, neuro-m predicted the water retention from bulk density and particle-size distribution with a mean accuracy of 0.04 m 3 m 3 . The relative improvement of neuro-m over neural networks that was optimized to fit the parameters (neuro-p) is 13%. Compared with a published neural network PTF, the new method is 30% more accurate and less biased.

Effects of solidification rate and ageing on the microstructure and mechanical properties of AZ91 alloy

Abstract: Sand-cast plates of a commercial AZ91C alloy have been used for the study. Varying the solidification rate by placing large cast-iron chills in the mould produced a range of secondary dendrite arm spacing (SDAS) within the cast plates. The plates were solution heat-treated. quenched and aged at 165 degreesC for up to 350 h. The SDAS (mum) varied with the solidification time, t(f) (s), as SDAS = 5.3 t(f)(0.43). The tensile ductility in the as-quenched (T4) condition did not depend on the solidification rate whilst in the T6 condition it tended to decrease for slowly solidified material (SDAS > 50 mum). The yield strength and hardness increased and the ductility decreased with ageing. The fracture mode changed from predominantly transgranular in the T4 condition to predominantly intergranular in the T6 condition. The properties of the sand-castings are compared with those of high-pressure diecastings and the possible strengthening mechanisms are discussed. A number of areas that require more research are pointed out. (C) 2002 Elsevier Science B.V. All rights reserved.

Phosphorus dynamics in the rhizosphere of perennial ryegrass (Lolium perenne L.) and radiata pine (Pinus radiata D. Don.)

Abstract: A short-term glasshouse experiment was carried out with two grassland soils to investigate phosphorus (P) availability and associated processes in the rhizosphere of perennial ryegrass (Lolium perenne L.) and radiata pine (Pinus radiata D. Don.) using a thin slicing technique. Results showed that readily extracted forms of soil inorganic P were depleted by both ryegrass and radiata pine, although depletion zones extended further adjacent to radiata pine (5 mm) compared with ryegrass (3 mm). Accumulation of bicarbonate extractable organic P occurred in rhizosphere soil under both ryegrass and radiata pine, which was related to increased levels of microbial biomass. Enhanced depletion of sodium hydroxide extractable organic P apparent in the rhizosphere of radiata pine compared with ryegrass was related to the presence of greater concentrations of water-soluble organic C, microbial biomass and higher alkaline phosphatase and phosphodiesterase enzyme activities. These results confirmed that microbial and enzyme activities played an important role in the mineralization of soil organic P, particularly under radita pine.

Modelling the impacts of climate change on Australian streamflow

Abstract: This paper presents the likely impacts of climate change on runoff, evapotranspiration and soil moisture in the more populated and important agricultural regions of Australia. The impacts are estimated by comparing the water fluxes simulated by a hydrologic model using present climate data and greenhouse-enhanced climate scenarios predicted by general circulation models. The results indicate that changes in rainfall are amplified in runoff. In wet and temperate catchments the percentage change in runoff is about twice the percentage change in rainfall, whereas in ephemeral catchments with low runoff coefficients the percentage change in runoff can be more than four times the percentage change in rainfall. The modelling study estimates that the annual runoffs in catchments on the northeast coast and east coast of Australia could change by −5 to +15% and ±15% respectively by the year 2030. The annual runoff in southeast Australia could decrease by up to 20%, and in Tasmania a ±10% change in runoff by 2030 is possible. The model simulates a decrease in the annual runoff in catchments in the South Australian Gulf of up to 25% by 2030, and a change of −25% to +10% in the runoff on the southwest coast of Australia. Although there are large uncertainties in these estimates, the results show the potential for climate change to bring about runoff modifications that may require a significant planning response. Copyright © 2002 John Wiley & Sons, Ltd.

Operationalizing biodiversity for conservation planning.

Abstract: Biodiversity has acquired such a general meaning that people now find it difficult to pin down a precise sense for planning and policy-making aimed at biodiversity conservation. Because biodiversity is rooted in place, the task of conserving biodiversity should target places for conservation action; and because all places contain biodiversity, but not all places can be targeted for action, places have to be prioritized. What is needed for this is a measure of the extent to which biodiversity varies from place to place. We do not need a precise measure of biodiversity to prioritize places. Relative estimates of similarity or difference can be derived using partial measures, or what have come to be called biodiversity surrogates. Biodiversity surrogates are supposed to stand in for general biodiversity in planning applications. We distinguish between true surrogates, those that might truly stand in for general biodiversity, and estimator surrogates, which have true surrogates as their target variable. For example, species richness has traditionally been the estimator surrogate for the true surrogate, species diversity. But species richness does not capture the differences in composition between places; the essence of biodiversity. Another measure, called complementarity, explicitly captures the differences between places as we iterate the process of place prioritization, starting with an initial place. The relative concept of biodiversity built into the definition of complementarity has the level of precision needed to undertake conservation planning.

Changes in fish communities of the Shoalhaven River 20 years after construction of Tallowa Dam, Australia

Abstract: This study was undertaken as part of a long-term investigation of the ability of high-level fishways to rehabilitate fish communities upstream of high dams. Effects of Tallowa Dam on fish of the Shoalhaven River system were studied by comparing species abundances, population size-structures and the structure of fish communities above and below the dam. Fish were sampled twice yearly for two years at 12 sites throughout the catchment. Species richness was greater downstream of the dam, with 21 species, compared to 16 species upstream of the dam. Ten diadromous species are believed to be extinct above the dam because of obstructed fish passage. Another four migratory species capable of climbing the wall have reduced abundances upstream. Accumulations of fish, particularly juveniles, directly below the dam were evident for nine species. Fish communities upstream and downstream of the dam differed significantly, identifying the dam as a significant discontinuity in the available fish habitats within the system. Historical evidence suggests that before the dam was built, fish communities from the tidal limit to at least 130 m elevation were largely continuous. This study has demonstrated that Tallowa Dam is a major barrier to fish migration and has had adverse effects on the biodiversity of the system. The creation of Lake Yarrunga by Tallowa Dam has resulted in distinctive fish communities in riverine and lacustrine habitats. Populations of five species that occur both upstream and downstream of the dam have developed differences in their size structures. The fish community downstream of the dam also differs from its historical condition because of the virtual disappearance of Australian grayling (Prototroctes maraena) and the establishment of non-native species. A high-level fishway is now being designed for the dam to restore fish passage. Data from this study will serve as a baseline against which to assess the effectiveness of the fishway in rehabilitating fish communities of the river system. Copyright © 2002 John Wiley & Sons, Ltd.

Global ENSO-streamflow teleconnection, streamflow forecasting and interannual variability

Abstract: El Nino Southern Oscillation (ENSO) has been linked to climate anomalies throughout the world. This paper presents an overview of global ENSO-streamflow teleconnection and identifies regions where the relationship may be exploited to forecast streamflow several months ahead. The teleconnection is investigated by fitting a first harmonic to 24-month El Nino streamflow composites from 581 catchments worldwide and the potential for forecasting is investigated by calculating the lag correlation between streamflow and two indicators of ENSO. The analyses indicate clear ENSO-streamflow teleconnections in many catchments, some of which are consistent across large geographical regions. Strong and regionally consistent ENSO-streamflow teleconnections are identified in Australia and New Zealand, South and Central America, and weaker signals are identified in some parts of Africa and North America. The results suggest that the ENSO-streamflow relationship and the serial correlation in streamflow can be used...

Genetics of Eucalyptus wood properties

Abstract: Traditional methods of assessing wood properties are both destructive and expensive, limiting the numbers of samples that can be processed. Over the past decade, non-destructive sampling techniques and new assessment methods have been developed leading to a large in- crease in the numbers of trees and traits that can be evaluated. This technology has enabled the assessment of progeny trials to determine the pat- terns of variation, degree of genetic control and economic importance of many wood traits, leading to the inclusion of wood properties in many eucalypt-breeding programs. Issues addressed in this paper include the potential markets and products for plantation eucalypts leading to a defi- nition of which wood properties should be assessed for a range of products. Current recommendations for non-destructive sampling for basic density, fibre length and predicted pulp yield in Eucalyptus globulus and E. nitens are provided. Other non-destructive assessment techniques are illustrated including cellulose content, acoustic testing methods for wood stiffness and SilviScan X-ray densitometry and diffraction analysis for density and microfibril angle. The degree of genetic control for wood properties is compared to tree growth traits and a series of issues and chal- lenges for the future presented. eucalypt / breeding / wood quality / genetic parameters / non-destructive sampling

Decreasing acetic acid accumulation by a glycerol overproducing strain of Saccharomyces cerevisiae by deleting the ALD6 aldehyde dehydrogenase gene

Abstract: Glycerol is a major fermentation product of Saccharomyces cerevisiae that contributes to the sensory character of wine. Diverting sugar to glycerol overproduction and away from ethanol production by overexpressing the glycerol 3-phosphate dehydrogenase gene,GPD2, caused S. cerevisiae to produce more than twice as much acetic acid as the wild-type strain (S288C background) in anaerobic cell culture. Deletion of the aldehyde dehydrogenase gene, ALD6, in wild-type and GPD2 overexpressing strains (GPD2-OP) decreased acetic acid production by three- and four-fold, respectively. In conjunction with reduced acetic acid production, the GPD2-OP ald6Δ strain produced more glycerol and less ethanol than the wild-type. The growth rate and fermentation rate were similar for the modified and wild-type strains, although the fermentation rate for the GPD2ald6Δ strain was slightly less than that of the other strains from 24 h onwards. Analysis of the metabolome of the mutants revealed that genetic modification affected the production of some secondary metabolites of fermentation, including acids, esters, aldehydes and higher alcohols, many of which are flavour-active in wine. Modification of GPD2 and ALD6 expression represents an effective strategy to increase the glycerol and decrease the ethanol concentration during fermentation, and alters the chemical composition of the medium such that, potentially, novel flavour diversity is possible. The implications for the use of these modifications in commercial wine production require further investigation in wine yeast strains. Copyright © 2002 John Wiley & Sons, Ltd.