|Input||Source of uncertainty||Method to reduce uncertainty|
|Selection of forest plots||Sampling error||
Forest plot geo-coordinates were selected using random number generation,
within logistical constraints, and good practice for sampling design and
forestry inventory was followed (MacDicken 1997, Pearson et al. 2005, Greenhalgh
et al. 2006, Grassi et al. 2008).
|Measurement of diameter at breast height (dbh)||Measurement error||
Training and education in measurement of dbh was conducted to reduce
measurement error. It was ensured that trees were not measured twice or dead
trees counted as living. Measurement uncertainty on a single tree of diameter
10 cm or greater has been estimated at 16% but found to average out at forest
stand level (Chave et al. 2004).
|Application of allometric equation||
allometric equations originating from Asian and Latin American data
Pan-tropical equations are based on a large number of trees from Asia and
Latin America spanning a range of diameters. Because destructive sampling of trees
to create an area-specific allometric regression equation was not possible, the
application of pan-tropical allometric equations was appropriate within dbh values used to create the regression
equations. Error attributable to the allometric equation is estimated at 10–20%
(Clark and Clark 2000, Keller et al. 2001, Ketterings et al. 2001, Chave et al.
|Application biomass to carbon ratio||
the carbon density of biomass components and tree species differ
|The IPCC 2006 present a default value of 0.47 for tropical and subtropical forest but within an interval estimate of 0.44–0.49. This is an improvement on 0.5 suggested by Westlake (1966), but suggests a relative error of 5%.|