Cristopher Brack

Pollution mitigation and carbon sequestration by an urban forest.

At the beginning of the 1900s, the Canberra plain was largely treeless. Graziers had carried out extensive clearing of the original trees since the 1820s leaving only scattered remnants and some plantings near homesteads. With the selection of Canberra as the site for the new capital of Australia, extensive tree plantings began in 1911. These trees have delivered a number of benefits, including aesthetic values and the amelioration of climatic extremes. Recently, however, it was considered that the benefits might extend to pollution mitigation and the sequestration of carbon. This paper outlines a case study of the value of the Canberra urban forest with particular reference to pollution mitigation. This study uses a tree inventory, modelling and decision support system developed to collect and use data about trees for tree asset management. The decision support system (DISMUT) was developed to assist in the management of about 400,000 trees planted in Canberra. The size of trees during the 5-year Kyoto Commitment Period was estimated using DISMUT and multiplied by estimates of value per square meter of canopy derived from available literature. The planted trees are estimated to have a combined energy reduction, pollution mitigation and carbon sequestration value of US

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

20-67 million during the period 2008-2012.

Carbon accounting model for forests in 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.

Estimating Tree Component Biomass Using Variable Probability Sampling Methods

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

As a signatory to the Kyoto Protocol, Australia is obliged to stabilize greenhouse gas emissions at 8% above 1990 levels by 2008–2012. To demonstrate achievement of this goal, Australia requires national annual estimates of changes in vegetation biomass as greenhouse gas emissions from land use change. These emission estimates are, however, uncertain due largely to the scarcity of existing allometric equations for calculating biomass. The large investment of time and funding required for harvesting, particularly using traditional techniques such as double regression and ratio sampling, also precludes the generation of new equations. Alternative techniques for rapid, cost-effective, and reliable estimation of biomass therefore require investigation. This study, conducted in central Queensland, compared estimates of component biomass that were generated for seven trees of the woodland species Eucalyptus populnea (poplar box) using ratio sampling and variable probability sampling techniques, namely randomized branch sampling (RBS) and RBS with importance sampling (IS). Application of randomized branch sampling consistently underestimated the biomass of leaf and small branches (<1 cm in diameter) and produced weak prediction equations. In contrast, results suggest that RBS with IS is particularly useful in predicting woody (trunk and branches >1 cm in diameter) biomass, and prediction equations agreed with existing equations for this species. However, this method tended to overestimate individual tree woody biomass. The study concluded that RBS with IS was a viable alternative to current methods.

Eucalyptus viminalis dieback in the Monaro region, NSW

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.

National forest inventories and biodiversity monitoring in Australia

Summary Over the last decade, substantial numbers of Eucalyptus viminalis across the Monaro plains in south-eastern NSW have been observed as declining in health. Based on a systematic road survey, the affected area is estimated to cover around 2000 km2, with almost all E. viminalis within that area either dead or severely affected. Other eucalypt species present show minor levels of health deterioration. Field observations include widespread infestation of an endemic but previously undescribed species of eucalyptus weevil (Gonipterus sp.). Eight sites were chosen to represent the range of management practices and recent fire history in the affected area. The structural complexity, tree health and level of weevil infestation were determined at each site, and despite large differences in structural elements and overall complexity, the severity of dieback was consistently severe across the range. There does not appear to be sufficient evidence to conclude that changed land management practices, recent fire history or declining levels of structural complexity are responsible for this ‘Monaro dieback’. If the dieback continues at the current rate, it seems inevitable that E. viminalis will disappear entirely from the Monaro region. As E. viminalis is the dominant species in most of the region, such disappearance will have very serious consequences on the ecology of the region. Further work is required to determine if the dieback is related to changes in climate or rainfall patterns. Trials of potential replacement E. viminalis genotypes and alternative eucalypt species should be undertaken as a precaution in case the dieback cannot be reversed.

Stand volume estimates from modelling inventory data

Abstract Forests currently cover over 20% of the Australian continent and are an important resource, subject to a wide range of economic and environmental pressures. These lands support substantial numbers of forest-dependent species with national forest inventories providing important information on biodiversity. National scale information on these forests has been collected or collated since 1988 under the National Forest Inventory (NFI) programme, but substantial problems with the ‘snap shot’ approach have been recognized, particularly with respect to monitoring change and a consequent move towards a permanent and sample-based continental forest monitoring framework (CFMF) has been proposed. CFMF is proposed to consist of three Tiers: (1) satellite imagery of the continent to identify forest and change in forest cover; (2) systematic high-resolution remotely sensed data and (3) permanent ground points at 20×20 km grid interception points. The CFMF approach is in line with the international trend of national forest inventories in developed countries although the Tier 2 approach offers a useful extension. An alternative inventory approach is provided by the National Carbon Accounting System (NCAS) which models the mass of carbon and nitrogen in seven separate living and dead biomass pools for any point under forest or agriculture land use since 1970. The NCAS approach allows fine spatial and temporal monitoring of changes in these carbon and nitrogen biomass pools, and predictions of changes that result from policy or management decisions. This paper briefly reviews NFI, NCAS and the proposed CFMF, with particular emphasis on issues of use and potential for monitoring biodiversity in this biologically very diverse country.

Bark probe—an instrument for measuring bark thickness of eucalypts

Summary Model-based sampling capitalises on relationships between the parameter of interest and other available data. In this inventory of the forests of North East Victoria, a model-based approach was used to sample an area of 227,000 ha, using 271 plots. Significant relationships were found between sawlog volume and several stand descriptors, including elevation, crown cover, stand height and species. A stratified random sampling approach would have required considerably more plots to achieve estimates of similar precision.

MODELLING CHANGES IN DIMENSION, HEALTH STATUS AND ARBORICULTURAL IMPLICATIONS FOR URBAN TREES

Summary The instrument consists of a modified solid brass cylinder through which moves a plunger tipped with a blunt needle. The needle is pushed through the bark to the wood surface and the depth of penetration is read from a scale on the barrel. The instrument enables fast and accurate measurements of bark thickness to be made on gum, peppermint and stringybark eucalypts. The measuring technique is virtually non-destructive and is simpler and more accurate and precise than other commonly used techniques, including the Swedish bark gauge.