Aboveground biomass models for trees and shrubs of exclosures in the drylands of Tigray, northern Ethiopia

作者：Ubuy Mengesteab Hailu^*; Eid Tron; Bollandsas Ole Martin; Birhane Emiru

来源：Journal of Arid Environments, 2018, 156: 9-18.

DOI：10.1016/j.jaridenv.2018.05.007

• Aboveground biomass
• Exclosures
• Destructive sampling
• Wood basic density
• Crown width

Globally, drylands cover large areas, but few models for estimation of biomass are developed for the relatively complicated tree and shrub structures found in this particular environment. A first set of general aboveground biomass models for exclosures in the drylands of the Tigray region, northern Ethiopia were developed from a large dataset with 305 destructively sampled trees and shrubs covering 50 different species and distinct growing conditions. Since biomass revealed nonlinear relationships to the independent tree variables, we used a non-linear least square modelling technique when fitting models. Selection of models was based on Pseudo-R-2, and root mean square errors and mean prediction errors (MPE) from a leave-one-out-cross-validation procedure. Pseudo-R-2 and relative MPE of the models varied from 0.76 to 0.84 and -3.7% to -1.5%, respectively. The large prediction errors observed when testing the "pan-tropical" models on our data, not only demonstrated the importance of developing the new models, but also indicated that careful considerations should done if the "pan-tropical" are planned for application in drylands elsewhere than Ethiopia. The new models may be applied generally for exclosures in Tigray for decision-support in forest management and as basis for reporting changes in carbon stock as required in the REDD + mechanism.

• 出版日期2018-9