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Albany, Australia

Paul K.I.,CSIRO | Roxburgh S.H.,CSIRO | England J.R.,CSIRO | de Ligt R.,Khan Research Laboratories | And 13 more authors.
Forest Ecology and Management

Plantings of mixed native species (termed 'environmental plantings') are increasingly being established for carbon sequestration whilst providing additional environmental benefits such as biodiversity and water quality. In Australia, they are currently one of the most common forms of reforestation. Investment in establishing and maintaining such plantings relies on having a cost-effective modelling approach to providing unbiased estimates of biomass production and carbon sequestration rates. In Australia, the Full Carbon Accounting Model (FullCAM) is used for both national greenhouse gas accounting and project-scale sequestration activities. Prior to undertaking the work presented here, the FullCAM tree growth curve was not calibrated specifically for environmental plantings and generally under-estimated their biomass. Here we collected and analysed above-ground biomass data from 605 mixed-species environmental plantings, and tested the effects of several planting characteristics on growth rates. Plantings were then categorised based on significant differences in growth rates. Growth of plantings differed between temperate and tropical regions. Tropical plantings were relatively uniform in terms of planting methods and their growth was largely related to stand age, consistent with the un-calibrated growth curve. However, in temperate regions where plantings were more variable, key factors influencing growth were planting width, stand density and species-mix (proportion of individuals that were trees). These categories provided the basis for FullCAM calibration. Although the overall model efficiency was only 39-46%, there was nonetheless no significant bias when the model was applied to the various planting categories. Thus, modelled estimates of biomass accumulation will be reliable on average, but estimates at any particular location will be uncertain, with either under- or over-prediction possible. When compared with the un-calibrated yield curves, predictions using the new calibrations show that early growth is likely to be more rapid and total above-ground biomass may be higher for many plantings at maturity. This study has considerably improved understanding of the patterns of growth in different types of environmental plantings, and in modelling biomass accumulation in young (<25 years old) plantings. However, significant challenges remain to understand longer-term stand dynamics, particularly with temporal changes in stand density and species composition. © 2014. Source

Paul K.I.,CSIRO | Roxburgh S.H.,CSIRO | England J.R.,CSIRO | Ritson P.,DAFWA | And 14 more authors.
Forest Ecology and Management

To quantify the impact that planting indigenous trees and shrubs in mixed communities (environmental plantings) have on net sequestration of carbon and other environmental or commercial benefits, precise and non-biased estimates of biomass are required. Because these plantings consist of several species, estimation of their biomass through allometric relationships is a challenging task. We explored methods to accurately estimate biomass through harvesting 3139 trees and shrubs from 22 plantings, and collating similar datasets from earlier studies, in non-arid (>300mm rainfallyear-1) regions of southern and eastern Australia. Site-and-species specific allometric equations were developed, as were three types of generalised, multi-site, allometric equations based on categories of species and growth-habits: (i) species-specific, (ii) genus and growth-habit, and (iii) universal growth-habit irrespective of genus. Biomass was measured at plot level at eight contrasting sites to test the accuracy of prediction of tonnes dry matter of above-ground biomass per hectare using different classes of allometric equations. A finer-scale analysis tested performance of these at an individual-tree level across a wider range of sites. Although the percentage error in prediction could be high at a given site (up to 45%), it was relatively low (<11%) when generalised allometry-predictions of biomass was used to make regional- or estate-level estimates across a range of sites. Precision, and thus accuracy, increased slightly with the level of specificity of allometry. Inclusion of site-specific factors in generic equations increased efficiency of prediction of above-ground biomass by as much as 8%. Site-and-species-specific equations are the most accurate for site-based predictions. Generic allometric equations developed here, particularly the generic species-specific equations, can be confidently applied to provide regional- or estate-level estimates of above-ground biomass and carbon. © 2013 Elsevier B.V. Source

Paul K.I.,CSIRO | Roxburgh S.H.,CSIRO | de Ligt R.,Khan Research Laboratories | Ritson P.,Forest Products Commission WA | And 10 more authors.
Forest Ecology and Management

Establishment of mallee eucalypt plantings on cleared agricultural land is currently the predominant method of reforestation for carbon sequestration in Australia. Investment in establishing and maintaining such plantings relies on having a cost-effective approach for providing un-biased estimates of yield in biomass and carbon sequestration. The Australian Government's forest carbon accounting model (FullCAM) had not previously been calibrated for mallee eucalypt plantings and, in many circumstances, substantially under-estimated of biomass for these plantings. Our objective was to improve model applicability and reliability of estimates of carbon sequestration. To achieve this, we first collected and analysed above-ground biomass data from 257 mallee eucalypt plantings (or 744 observations, when including the multiple measurements made at some planting sites) to determine the key factors influencing growth. Plantings were categorised according to species, planting configuration (block or belt plantings) and stand density. Each category of planting had significantly different rates of growth, with the rates of sequestration of above-ground biomass carbon being relatively high when established in densely-stocked, two-row belts. These categories of plantings then provided the basis for calibration (estimation of appropriate modifiers) of FullCAM growth curves. Overall model efficiency was 63%, and there was no apparent bias when the model was applied to the various planting categories. Thus, modelled estimates of biomass accumulation will be reliable on average but at any particular location will be highly uncertain, with either substantial under- or over-prediction possible. For some categories of mallee eucalypt plantings, and for plantings with access to ground-water or established in non-productive soils, there were insufficient observations to provide confidence in new calibrations specific for these circumstances. Moreover, application of the calibrations provided here are applicable for prediction of sequestration of biomass carbon of relatively young (<15-year-old) stands, with more data needed for prediction of longer-term rates of growth. © 2014. Source

Nansen C.,University of Western Australia | Nansen C.,University of California at Davis | Ferguson J.C.,University of Queensland | Moore J.,Western Australia DAFWA | And 5 more authors.
Agronomy for Sustainable Development

The overuse of pesticides leads to contamination of water and food. Therefore, there is a need for tools and strategies to optimize pesticide application. Here we present SnapCard, a user-friendly and freely available decision support tool for farmers and agricultural consultants, available at snapcard.agric.wa.gov.au. SnapCard allows to predict, measure, and archive pesticide spray coverage quantified from water-sensitive spray cards. Variables include spray settings such as nozzle orifice size, sprayer speed, water carrier rate and adjuvant, and weather variables such as barometric pressure, relative humidity, temperature, and wind speed at ground level. We use separate regression models for four nozzles types. Our results showed that there are strong and positive correlations between water carrier rate and spray coverage for all four nozzle types. Moreover, sprayer speed is highly negatively correlated with obtained spray coverage. In addition, there is no consistent effect of either nozzle type or use of a particular adjuvant, across water carrier intervals. We conclude that varying combinations of spray settings and weather conditions caused marked ranges of spray coverages among the four nozzle types, thus highlighting the importance of selecting the right nozzle orifice size and type. We demonstrate that realistic scenarios of environmental conditions and spray settings can lead to predictions of very low spray coverage with at least one of the four nozzle types. We discuss how the novel and freely available smartphone app, SnapCard, can be used to optimize spray coverage, reduce spray drift, and minimize the risk of resistance development in target pest populations. © 2015, INRA and Springer-Verlag France. Source

Ghaffari M.H.,University of Western Australia | Durmic Z.,University of Western Australia | Real D.,Western Australia DAFWA | Real D.,University of Western Australia | And 3 more authors.
Animal Production Science

The objective of this study was to investigate the effects of the forage shrub tedera (Bituminaria bituminosa) on nutrient digestibility, rumen microbial fermentation and furanocoumarins degradation in the rusitec. The variables were measured in fermentation liquid on Days 13 and 17 and were compared with a control (lucerne hay). Overall, tedera had greater (P < 0.05) neutral detergent fibre and acid detergent fibre digestibility than lucerne hay on both days of the experiment, but on Day 17 it had lower (P < 0.01) dry matter and crude protein digestibility than lucerne hay. There were no significant differences in concentration of NH3-N and pH between treatments, but NH3-N concentrations in both treatments were lower (P < 0.05) on Day 17 than on Day 13. The concentration of total volatile fatty acids in vessels were not affected by treatments, but the concentration of acetate was lower and acetate-to-propionate ratio higher (P < 0.05) in tedera than lucerne hay on Day 13 of the experiment. Furanocoumarins were detected in the tedera treatment only. Their concentration in the fermentation liquid increased immediately after the addition of the plant material to the fermenter, reaching highest concentrations after 2 h. These concentrations gradually declined over the next two sampling times, but 6 h after the 'feeding', they were still detectable in the fermentation liquid. It was concluded that (i) tedera had in vitro digestibility and fermentability variables comparable to lucerne; (ii) furanocoumarins were degraded in the fermentation fluid, and (iii) furanocoumarins from tedera did not seem to impede microbial fermentation. Tedera may provide an alternative feed source to hay and grain for filling the summer-autumn feed gap without negatively affecting nutrient digestibility and rumen microbial fermentation. © 2015 CSIRO. Source

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