Allometric equations for estimating biomass in agricultural landscapes: I. Aboveground biomass

• Published in: Agriculture, ecosystems & environment Vol. 158; pp. 216 - 224
• Main Authors: Kuyah, Shem, Dietz, Johannes, Muthuri, Catherine, Jamnadass, Ramni, Mwangi, Peter, Coe, Richard, Neufeldt, Henry
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier B.V 01-09-2012; Elsevier
• Subjects: Aboveground biomass; Agricultural mosaics; Agronomy. Soil science and plant productions; Allometric equation; Biological and medical sciences; Biomass; Breast; Carbon; Carbon stocks; Estimates; Farmlands; Fundamental and applied biological sciences. Psychology; General agroecology; General agroecology. Agricultural and farming systems. Agricultural development. Rural area planning. Landscaping; General agronomy. Plant production; Generalities. Agricultural and farming systems. Agricultural development; Landscapes; Mathematical analysis; Trees; Western Kenya; Kenya; East Africa; Sub-Saharan Africa; Africa; Carbon stocks; Western Kenya; Agricultural mosaics; Allometric equation; Aboveground biomass; Epigeal; Rural environment; Tropical zone; West; Equation; Ecology; Biomass; Allometry; Carbon; Agricultural landscape; Above ground plant part; Agriculture
• ISSN: 0167-8809; 1873-2305
• DOI: 10.1016/j.agee.2012.05.011

► Local generic equation was developed from empirical, destructive measurements. ► The equation has low error with only dbh and has potential for up-scaling. ► Wood density data improve model fit, height data did not. ► Large trees are few in the landscape but hold most of the biomass. ► Published equations that match climatic conditions of Western Kenya misjudged biomass.
Meeting the reducing emissions from deforestation and degradation (REDD) framework demands stringent carbon measuring, reporting and verifying methods. In most cases, estimates of aboveground carbon stocks rely on allometric equations. Although generic and species-specific allometries have been developed for conventional areas such as forests, their use in agricultural landscapes is questionable as agricultural trees are typically managed and rarely mono-specific. Therefore, there is a need to develop a robust generic allometry that accounts for the heterogeneity of tree diversity throughout the landscape. Allometric equations were developed from empirical destructive sampling of 72 trees (diameter at breast height (dbh): 3–102cm) from three 100km2 benchmark sites in Western Kenya. Diameter at breast height alone provided reliable prediction for aboveground biomass (17±0.02MgCha−1) with >95% accuracy. Published equations overestimated landscape biomass due to errors in either smaller trees (dbh <10cm) which dominate the landscape (66%) or the few larger trees (dbh >40cm) which constitute 3% of all the trees but hold most of the biomass (48%). The apparently small differences in the equations for small trees could add up to a large amount of carbon when looking at a landscape. This study recommends diameter as the basis for assessing tree biomass in Western Kenyan agricultural mosaics. The equations developed are a useful tool for assessing the potential for carbon sequestration in agricultural landscapes and represent key information for scaling biomass estimates for entire landscapes.