Program A: Measurement & spatial estimation of carbon pools and turnover

An Overview of the 2001- 2002 Research Year and Prospects

During the third year of CRC activity, the newly formed Program strengthened collaboration within the CRC and externally to make the following important contributions:

• Establishment of a new field research site at Billy Billy in the ACT for studying soil carbon input and turnover under adjacent pasture and pine plantation.
• Construction and instrumentation of field temperature gradient tunnels for study of above- and below-ground carbon dynamics of pastures in response to elevated CO2 concentration and warming.
• Development of controlled incubation procedures for stabilising the effects of soil water availability on the mineralisation of organic matter and its protection in the soil.
• Demonstration that burning significantly changes the d13C signature of litter derived from C4 grasses. This is important for interpretation (inference) of change from C4 to C3 vegetation (eg. woody thickening) based on changed soil carbon isotopic composition.
• Publication of several major reviews covering:
  • effects of LUC on soil carbon
  • non-CO2 emissions from Australian agriculture
  • vegetation thickening
  • effects of management on soil C.
• Demonstration that the carbon content (both organic and inorganic) is highly spatially variable in saline agricultural catchments. Variation may be due to topographic variation in native soil carbon, changes in carbon input from vegetation during salinisation, changes in soil C mineralisation rates, and lateral transfer of carbon within the catchment. Carefully designed studies are needed to quantify soil C change resulting from salinisation or management practices designed to reverse it.
• Publication of long-term data that demonstrate a significant carbon sink in Queensland’s grazed woodland, that may be human-induced. Studies using soil carbon isotope signature change to explore the nature and timing of woody thickening have commenced.
• Demonstration that a single allometric equation, based on tree diameter at breast height (DBH), can be used to accurately estimate the biomass of Eucalyptus pilularis trees growing either in plantations or natural forests in highly contrasting environments. Establishment of the generality of such equations greatly simplifies the estimation of forest biomass at catchment and regional scales.
• Quantification of the root:shoot ratio in forest plantations growing under contrasting conditions, and development of hypotheses describing how site factors and forest management influence the ratio. The root:shoot ratio in several studies is much higher than previously assumed in carbon accounting methods for woody vegetation.
• Demonstration that Lidar is a useful tool for scaling-up plot estimates of biomass to catchment and larger scales.
• Studies of sawlog recovery after forest harvesting, and of sawn wood recovery, show that only 14 and 30%, respectively, of the carbon in felled Eucalyptus pilularis and Pinus radiata trees ends up in long-lived sawn timber product.
• Field studies have shown that wood is only slowly decayed (4% mass loss over 19 years) in landfill sites in Sydney.
• Completion of a major survey (1200 respondents) of the use and service life of wood products.
• On-going contributions to greenhouse policy and its implementation via contributions to development of Australia’s National Carbon Accounting System (NCAS), support for the growth of forest bioenergy both nationally and internationally, and input to writing the IPCC Good Practice Guidance Report for the LULUCF sector.