Gary Richards

Development of a carbon accounting model (FullCAM Vers. 1.0) for the Australian continent

Summary Continental-scale carbon accounting capable of the spatial and temporal distinctions demanded by the Kyoto Protocol requires a modelled approach which integrates over space and time the effects of changing land use, land management and climate variability. To assist in the development of Australias National Carbon Accounting System (NCAS), the Australian Greenhouse Office has developed and calibrated an integrated suite of models relevant to Australian conditions for which data were available or could be generated for their application. These point-based models were then made operational within a GIS environment to enable application at a fine spatial (25 m) and temporal (monthly) resolution for the Australian continent. This paper focuses on the FullCAM model, capable of carbon accounting in transitional (afforestation, reforestation and deforestation) and mixed (e.g. agroforestry) systems. The FullCAM model can be run in a spatial mode which integrates information drawn from remotely-sensed land-cover change, modelled productivity surfaces, mapped resource inventories and other ancillary data to perform the various accounting procedures for Australias NCAS. This framework has been developed in parallel with a range of data collation, model calibration and verification activities across the continent. The framework provided by FullCAM has allowed highly specific and therefore targeted and cost-effective model calibration and verification activities. FullCAM, as the analytic model for Australias NCAS, will continue to be refined within the established framework.

A continental biomass stock and stock exchange estimation approach for Australia.

Summary To implement Australias National Carbon Accounting System it is necessary to estimate biomass stock, continentally, and change in stock, at a sub-hectare spatial resolution. The approach developed to meet this requirement is a hybrid between GIS-based process modelling and empiricism. Multi-temporal mapping of productivity was carried out using a variant of the 3PG (physiological principles predicting growth) model. Relationships were found between mapped productivity indices and measurements of biomass at maturity (i.e. long-term- undisturbed stands). This information was then used to interpolate maps of biomass potential. Simple growth formulae were used to plot biomass accumulation, with the ‘rate of approach to mature biomass’ set by the age at which maximum current annual increment occurs and the predicted site plant productivity over time. The age of the forest stand was determined from disturbance events detected by twelve national coverages of Landsat MSS, TM and ETM+ remotely-sensed data collected between 1972 and 2002. Responses to thinning of existing forests are calculated using an adjustment of stand age concurrent with the intensity of the thinning event.

Carbon accounting model for forests in Australia

CAMFor (Carbon Accounting Model for Forests) is a sophisticated spreadsheet model developed to assist in carbon accounting and projection. This model can integrate information from a range of alternate sources including user input, default parameters and third party model outputs to calculate the carbon flows associated with a stand of trees and the wood products derived from harvests of that stand. Carbon is tracked in the following pools: * Biomass (stemwood, branches, bark, fine and coarse roots, leaves and twigs) * Soil (organic matter and inert charcoal) * Debris (coarse and fine litter, slash, below ground dead material) * Products (waste wood, sawn timber, paper, biofuel, reconstituted wood products). These pools can be tracked following thinning, fires and over multiple rotations. A sensitivity module has been developed to assist examination of the important assumptions and inputs. This paper reviews the functionality of CAMFor and reports on its use in a case study to explore the precision of estimates of carbon sequestration in a eucalypt plantation. Information on variability in unbiased models, measurement accuracy and other sources of error are combined in a sensitivity analysis to estimate the overall precision of sequestration estimates.

A modelled carbon account for Australia's post-1990 plantation estate

Summary Australias national carbon account for afforestation and reforestation activities qualifying under Article 3.3 of the Kyoto Protocol between 2008 and 2012 can be estimated using a carbon accounting model supported by a range of forest-related data. Using inventories of current plantation areas and projected expansion of the plantation estate, it is possible to project carbon sequestration in 36 known plantation management regimes to give an annual national account of net (sequestration minus emissions) carbon stock change. Data for the modelling were provided through a range of studies undertaken for the development of the National Carbon Accounting System (NCAS). These included compendiums of available information on management regimes, plantation growth and yield, wood density, carbon contents and allocations to non- stem components of trees. Future refinements of the modelling will include the extraction of a ‘mask’ of relevant afforestation and reforestation activities from the continental multi-temporal Landsat satellite coverages of Australia developed for the NCAS. Other improvements will include the use of the NCAS national annual 1 km grid productivity mapping to determine variability in growth associated with variability in climate and soil characteristics. Soil carbon modelling capability using the Roth C model will also be possible when the spatial mapping is complete and details of plantation areas can be merged with the relevant maps of soils and climate.

Total above-ground biomass and biomass in commercial logs following the harvest of spotted gum (Corymbia maculata) forests of SE NSW

Summary Total stand above-ground biomass (AGB) was measured at three sites of varying productivity in the Batemans Bay region of NSW. All trees with diameter at breast height (dbh) > 10 cm on three plots of 0.4–0.6 ha were weighed. Spotted gum was the dominant tree species across all sites. The basal area ranged from 29 to 43 m ha−1 depending on site quality. The total dry AGB was 220, 287 and 397 t ha−1 for the low, medium and high-quality sites (LQS, MQS and HQS), respectively. Spotted gum accounted for 66–79% of the AGB. The proportion of AGB in larger trees (dbh >50 cm) increased significantly with increased site quality. Bark accounted for about 7% of the weight of all spotted gum logs. The only significant differences in the proportion of bark in the logs were between trees with dbh >70 cm and those with dbh <40 cm. Ironbark had the highest proportion of the log biomass in the bark (12.4%). The mean moisture content of spotted gum logs was similar to that of Sydney blue gum and yellow stringybark logs. The moisture content of ironbark logs was significantly lower than that of all other species tested, whereas its basic density was higher than that of all other species. A strong correlation (r = 0.947) was found between tree diameter and AGB for spotted gum across all sites. Most trees on all sites were < 30 cm in diameter (particularly at the low-quality site), and the variance of AGB increased with tree size. The fraction of biomass in all spotted gum commercial logs was 58.2%. The biomass in commercial logs at the MQS was significantly greater than that at both the LQS and the HQS. An average 0.8 t of residues was generated per tree as a result of selective harvesting of commercial spotted gum forests. The largest fraction of biomass in commercial spotted gum logs (64.1%) was found in large trees (55–65 cm dbh), although the only significant differences were between trees with dbh between 35 and 40 cm and those with dbh between 55 and 65 cm. Pulp logs accounted for 55% of the AGB harvested in spotted gum commercial logs. The proportion of higher-quality commercial logs increased with increased site quality.

Developing a carbon stocks and flows model for Australian wood products

Summary This paper describes the development of a model for estimating Australias stocks and flows of carbon in harvested wood products, including estimates of atmospheric emissions. The model estimates emissions in various forms, including those from wood products contained in Australia, encompassing both domestically produced (net of exports) and imported wood products. This estimate is the basis of Australias National Greenhouse Gas Inventory report on wood products. The model can also estimate emissions from all (and only) wood products produced in Australia, and a third variant that presumes emissions from wood products at the time of harvest. The model represents a collaborative effort, involving relevant Commonwealth and state government agencies, industry groups and research bodies. The model uses available statistics on log flows from forest harvest and estimates of the carbon content of the various wood products processed (for example, sawn timber, plywood, pulp and paper and woodchips) to determine carbon inputs to wood products. The model uses estimates of the decay period of various classes of wood product to calculate the pool of carbon in wood products. Crosschecking with independent input data was done wherever possible to test the robustness of various input data used in the model development. The model is built in Microsoft Excel with all rate and age parameters easily accessed and varied for sensitivity testing using the @Risk software. Wood products in use are assigned to young-, medium-and old-age pools. Simulated losses of wood products from their service life occur from each of the young-, medium-and old-age pools. Material leaving service is either transferred to bioenergy, added to landfill, recycled or emitted to the atmosphere. Losses of carbon can also occur from the landfill pool. The recorded imports and exports of wood products are used to calculate emissions under two approaches. The first is from wood products produced in Australia (but not necessarily remaining within Australia), and the second from wood products stored in Australia (wherever they were produced). Further simulations, with and without consideration of storage and emissions from landfill, are then run for each approach. The results show that an accounting approach that presumes emissions from wood products at harvest over-estimates emissions to the atmosphere when compared with approaches that consider the service life of wood products. The storage of wood products in landfill is also significant.