think climate. think change.
Department of Climate Change
Roger M. Gifford, September 2000
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National Carbon Accounting needs to adopt generalising values for the % carbon (C) content of the above-ground parts of trees in Australia. For many C-cycle models the C:nitrogen (N) ratio is also an important attribute. The %C and %N content in the bark, sapwood, wood at the centre of stems, branch wood, green leaves and recently dead leaf litter were determined for 19 diverse native tree species of eastern Australia and Pinus radiata.
The species-mean carbon contents determined for individual tissues all fell within the range 45% to 55%. The overall unweighted mean across all tissues and species was 50%. Green leaves of native species had significantly higher C contents (average 52.8%) than all other standing tree tissues. Leaf litter had even higher C content (54.3%). For P. radiata the green leaves did not have higher C contents than all other standing tree tissues (51.1%), deepwood having a mean content of 54.1%. Nitrogen contents were much more variable than C contents. No simple generalising relationships with branch or stem diameter were found for either C contents or C:N ratios. It is recommended that where a single %C content is required to represent the above-ground parts of all types of tree a value of 50±2% be adopted.
Where leaves are represented separately from woody tissues, a value of 53±2% is appropriate for leaves and 50±2%C for the woody parts of native species. For P. radiata 50±2% is probably a suitable figure, both for the overall tree and for leaf, for broad-scale inventory purposes. For project-plantation purposes involving P. radiata and possibly other mono-specific plantations, which may involve C-trading, location/species-specific data may be advantageous and is recommended.
