"The improvements in accuracy and increases in estimates of carbon in plants could increase the value of forests as carbon sinks and provide more-robust data that could underpin carbon trading," the CRC said.
The value of the mallee tree as a potential carbon sink plantation is due in part to its extensive root system, making it able to store relatively high levels of carbon dioxide compared to alternative plants.
The root:shoot ratio is a common descriptor of the relationship between root and shoot biomass, used for estimating root biomass from the easily measured shoot (above ground) biomass.
The CRC for Greenhouse Accounting has collected specific root:shoot data for a wide variety of vegetation and applied it to the current analysis of the global carbon budget.
Using the new root:shoot data, the CRC's analysis indicated a 50% increase in estimated global root carbon stock and a 12% increase in estimated total carbon stock of trees and other plants.
Effectively, the new research suggests that global estimates on the carbon offset value of carbon sink plantations have been significantly underestimated.
According to the CRC for Greenhouse Accounting, previous reviews of the carbon offset value of vegetation had been examined less specific root:shoot ratio data, and have not always critically reviewed the data used.
The CRC said its studies demonstrated the need for more reliable root:shoot ratios to improve the accuracy of root biomass estimates, including those required for estimating the effects of land management and land-use change in National Greenhouse Gas Inventories.
The CRC said that although it had discovered that a single root:shoot ratio derived from the various root:shoot ratio data had been reasonably accurate when applied to forests and woodlands, the increased accuracy of vegetation-specific data would improve carbon accounting techniques.
