Aboveground Biomass Expansion Factors
Signatories to the United Nations Framework Convention on Climate Change and its subsequent Kyoto Protocol have pledged to reduce their emissions of greenhouse gases. Understanding the ability of the Earth's forests to take up greenhouse gases, such as carbon dioxide, from the atmosphere is vital. Hence, the Kyoto Protocol has targeted the creation of carbon inventories. Biomass Expansion Factors (BEFs) are one method employed by scientists to estimate the amount of carbon (in metric tonnes) per cubic meter of forest. Participants in the CARBO_INVENT project calculated Aboveground Biomass Expansion Factors (ABEFs) for several different species in Catalonian forests. ABEFs are the ratio of aboveground biomass to stem volume and hence do not take root mass into account. Dasometric and dendrometric data for the Spanish forests was retrieved from the existing Ecological Forest Inventory of Catalonia (IEFC). What was discovered was a large degree of variability in ABEF between species; the minimum (Pinus radiata) and maximum (Quercus ilex) ABEFs differed by a factor of three. The scientists attributed this primarily to differences in wood density and to a lesser extent to differences in branch biomass. This is despite the fact that carbon content was relatively constant across species. Another point of interest was that fast-growing trees generally had lower ABEFs. These findings illustrate the importance of accurately differentiating among species when constructing a carbon inventory using ABEFs.
