ARWA Centre for Ecohydrology
Seeking to Understand and Manage Water

Oil Mallee Biomass Estimation

Jun Jet Liew's honors project "Carbon Sequestration of Eucalyptus polybractea roots in the south west wheatbelt of Western Australia", supervised by Kim Brooksbank from the CoEE's Albany office, is being funded by industry partner the Rural Industries Research and Development Corporation (RIRDC).

The Oil Mallee Industry of Western Australia is advocating mallee as suitable for multiple markets including carbon trading. To justify this they need to show that long term carbon value is being accumulated in the below ground biomass even as above ground biomass is displaced during harvest. Investigation of the relationships between above and below ground biomass and the comparison of coppiced trees to uncut trees will hep Jun Jet to develop a method to estimate below ground biomass based on non-destructive above ground measurements. Her research is based on the theory that root:shoot ratios increase as mallees are coppiced in rotations over long periods.

AIMS


  • Obtain a better understanding of the rate that E. Polybractea sequesters carbon by quantifying root growth in both uncut and coppiced trees across three different ages.
  • Investigate the relationships between above to below ground biomass and the effect of coppiced trees compared to uncut trees with similar site characteristics.

OUTCOMES


  • Establish relationships between; tree age and root biomass, tree age and above ground-below ground biomass ratios, total biomass and leaf area, above ground woody volume and below ground volume based on tree height and basal diameters, basal diameters and above ground biomass, basal diameters and below ground biomass.
  • Suggest a basic method of estimating below ground biomass based on non-destructive above ground measurement.
  • Suggest areas for further investigation for management practices consideration of E. Polybractea in farming systems.
  • Quantify total organic carbon in above and below ground structures of E. Polybractea

Project Summary

The integration of mallee plantings into farming systems is being promoted as a method to further develop the agricultural industry and to rehabilitate degraded land in the Western Australian wheatbelt. The study recognises the potential of the mallee industry to

  • transform existing industries
  • overcome salt-affected land
  • use native deep-rooted perennial species for land remediation
  • respond to climate variability by encouraging plant-based carbon sinks.

This study advocates the need to develop understanding of mallee root growth to aid in quantifying root biomass of mallees and provide insight into the sustainability of both the farming and mallee industry and commercial returns.

Jun Jet Liew
This project is being undertaken by Jun Jet Liew under the supervision of Kim Brooksbank and A/Prof Neil Coles.