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  • Woody Biomass Productivity and Potential Biomass Industries in the Upper South East

    A report for the SA Centre for Natural Resource Management

    by Trevor Hobbs, Peter Georgaras, Merv Tucker, Craig Neumann and Mike Bennell

    FloraSearch Project / SA Department of Water, Land and Biodiversity Conservation / Cooperative Research Centre for Plant-based Management of Dryland Salinity

    2006

  • © 2006 SA Department of Water, Land and Biodiversity Conservation. All rights reserved.

    Ref: Hobbs, T.J., Georgaras, P.A., Tucker, M., Neumann, C., Bennell, M. (2006). Woody Biomass Productivity and Potential Biomass Industries in the Upper South East. A report for the SA Centre for Natural Resource Management. FloraSearch Series. SA Water, Land and Biodiversity Conservation, Adelaide. 128pp.

    Researcher Contact Details Trevor Hobbs SA Water, Land and Biodiversity Conservation Waite Road, URRBRAE SA 5064 Phone: 08 8303 9766 Fax: 08 8303 9320 Email: hobbs.trevor@saugov.sa.gov.au

  • i

    Executive Summary The natural resources of South Australia’s Upper South East provide the backbone of a diverse range of ecosystems, agricultural pursuits, industries and communities. However, the region is significantly affected by the natural resource management issues of dryland salinity, and ecosystem fragmentation/degradation. The loss of perennial vegetation cover has contributed substantially to these natural resource management issues and it is well recognised that there is a role for agroforestry, perennial farming systems and habitat re-creation to alleviate some of these problems. Woody biomass industries can provide both environmental services and economic opportunities through the development of commercial revegetation in the Upper South East.

    This report outlines the range of woody biomass industries that can potentially service the Upper South East region. Some industry types, such as fodder shrubs for livestock, pulpwood and firewood, already exist in the region and could be significantly expanded with little or no new investment in industrial infrastructure. New industries based on bioenergy and Eucalyptus oil or combined in an Integrated Tree Processing plant (eg. Narrogin WA oil mallee plant) have strong potential in the region but may require significant investment in new infrastructure to proceed.

    Any woody biomass industry development is dependant on the selection of species which match both industry product and yield specifications, and can produce sufficient economic volumes of biomass in the region. Information on plantation productivities in the Upper South East is limited to a few trials of forestry species primarily aimed at long-cycle hardwoods for lumber production. Production rates of species aimed at short-cycle woody biomass crops are poorly known. To determine the biomass production rates and product yields in current and future plantations we have developed robust allometric relationships between simple plant measurements (biometrics) and their stemwood volumes, total above-ground biomass and carbon contents.

    This study provides very strong allometric relationships between simple measures of plant morphology and standing plant biomass (r²=0.88). Simple classifications of species groups and lifeforms can improve the predictive capability of these models by a further 4%. Data from the Upper South East and River Murray Corridor biomass studies provide robust relationships that can be applied across a wider range of species and environments in South Australia. Using these relationships we have been able to revisit data collected from other farm forestry trials and rapidly evaluate the primary productivity of other plantations in the region. Using productivity data from groups of species that match pulpwood, bioenergy, oil mallee, fodder shrubs and habitat re-creation industries, we have built spatial models of woody biomass production and carbon sequestration potential for each industry type.

    In the Upper South East region there are 1.39 million hectares of land currently used for annual cropping and livestock grazing that could potentially be used for woody biomass crops. Leakage of water from the current cropping/grazing farming systems contributes on average around 26 millimetres of recharge every year which equates to 360 Gigalitres across the entire region. Plantations of woody crops on these landscapes would virtually eliminate recharge, greatly reduce the progression of dryland salinity, reduce wind erosion risk and provide additional biodiversity benefits. Additional benefits would also be gained from atmospheric carbon dioxide sequestration. The environmental benefits of revegetation have been quantified for each Hundred subdivision in the

  • ii

    region. A combination of dryland salinity, wind erosion and habitat loss risk indices were used to identify which districts would most benefit from woody perennial crops - these are focussed on the central part of study area, near the town of Tintinara and including lands to the west of Keith.

    Existing broadacre annual cropping and livestock grazing provide an average gross margin return of around $121 per hectare (based on average returns 1996-2005). As could be expected with annual- based crops and pastures these returns are highly variable over time, ranging from losses of over $-200/ha to profits of over $400/ha in good seasons. Woody perennial crops provide more consistent returns as the robust woody crops generally survive droughted conditions and can make the most of unseasonal rainfalls. Our integrated spatial analysis of plantation productivity and farm economics (Regional Industry Potential Analysis) for several industry types show that expanded pulpwood industries could provide annual equivalent returns of between $132 - 1006/ha (region average range = $415 - 476/ha). Firewood industry average annual returns for the region would be in the vicinity $229 - 280/ha, and fodder shrubs in Autumn would be worth $147/ha. The prospective industries of bioenergy and Eucalyptus oil extraction based on new infrastructure at Keith would provide annual returns of around $380 - 433/ha, and single purpose carbon sequestration planting would create annual returns up to $43/ha (average $10 - 12/ha) for habitat and oil mallee plantings but could be higher than $500/ha (average $370/ha) for permanent woodlots of Sugargum (Eucalyptus cladocalyx) or similar species.

    Several of the woody biomass industries analysed here could provide economic returns which are competitive with existing cropping and grazing landuses in the region. Rather than a total displacement of existing annual cropping and grazing systems in the Upper South East region, we envisage these new woody biomass industries will provide new options and opportunities for farmers and existing industries of the region. These new options can be strategically placed to become an integral part of a healthy mosaic of new woody perennial-based and existing annual-based primary industries. In our landscapes that are subject to the risks of rising water tables, dryland salinity, soil erosion, habitat loss, climate change, and economic and community sustainability, there appears to be a sound future for woody perennial cropping in the Upper South East region.

  • iii

    Contents

    Executive Summary .................................................................................................................. i Contents.............................................................................................................................................. iii List of Tables...................................................................................................................................... iv List of Figures ..................................................................................................................................... v Acknowledgements ........................................................................................................................... vii

    1. Introduction....................................................................................................................... 1 2. Biomass Productivity ...................................................................................................... 11

    2.1 Introduction ........................................................................................................................... 11 2.2 Plant Biometrics and Allometric Relationships..................................................................... 12 2.3 Plantation Productivity .......................................................................................................... 30 2.4 Regional Productivity............................................................................................................ 38

    3. Natural Resource Management Issues and Benefits of Revegetation........................ 51 3.1 Introduction ........................................................................................................................... 51 3.2 Soil Salinity and Wind Erosion Risk..................................................................................... 51 3.3 Ecosystem Fragmentation and Degradation .......................................................................... 52 3.4 Overall Environmental Risk .................................................................................................. 53 3.5 Carbon Sequestration Potential ............................................................................................. 53

    4. Biomass Industries - Prod