The measurement of plantations of trees in Western Australia to improve the estimates of carbon sequestration in low rainfall areas
Australian Greenhouse Office Community Partnership Collection
Hassall and Associates Pty Ltd
Environment Australia, 1999
ISBN 0 6425 4654 1
This report investigates the estimation of carbon sequestration from tree planting in low rainfall areas in Western Australia.
A 'Community Tree Planting Program' sponsored by Alcoa of Australia Ltd, for a range of social and community benefits, ran throughout the 1980s and supplied thousands of trees to community groups - some in low rainfall areas. The Program thus provided a range of sites from which tree growth, and hence carbon sequestration, could be estimated.
The report provides site descriptions and biomass measurements and biomass measurements for 16 sites in Western Australia. Some sites were divided into smaller sub-plots, in order to measure single species as much as possible, because of planting design and to allow for site variation. Data for two sites was obtained from publications, and data for another two sites comes from the Water and Rivers Commission of Western Australia.
Previous data for the estimation of biomass accumulation have been from sites with a single species, which is managed for maximum growth rates (commercial plantations, plantings for effluent reuse, etc.). The reasons for planting trees in the sites measured in this study are much more diverse, and include lowering of groundwater tables, reducing recharge, firewood, shade and shelter, beautification and degradation control as well as for commercial timber harvesting.
Nearly all sites measured had access to shallow water tables, which is a reflection of what was in many cases the original reason for the planting - to lower water tables (which several sites actually achieved). This limits the use of the data for applications regarding rainfed biomass accumulation.
Growth rates were not able to be calculated because of a very high variability in the results and young age of most of the plantings. With the exception of one extreme value, which came from a very small trial plot, the biomass figures were consistent with those produced in previous studies by Hassall & Associates. The majority of the carbon sequestration values for the sites fell within the expected range of productivity classes, based on rainfall and other site factors. The rates of growth for the Southern Blue Gum exceeded the expectations for the relevant productivity class.