Research NoteEstimation of browse biomass of Ficus thonningii, an indigenous multipurpose fodder tree in northern Ethiopia

Abstract

Ficus thonningii is a multipurpose browse tree in northern Ethiopia. Despite its importance, techniques for quantifying its browsable biomass have not been developed. To develop best-estimation equations, the dendrometric parameters total height (H), crown height (CH), crown diameter (CD), diameter at stump height (DSH), diameter at breast height (DBH), crown depth (CDp), crown area (CA) and crown volume (CV) were measured from 12 sampled trees comprising three age ranges. Leaves and edible twigs of the sampled trees were clipped, oven dried, weighed and recorded as dry weight (DW). Regression analysis and a multicollinearity test were employed to remove non-significant predictors of DW. Results showed that only CV, CA, CD, CDp and DSH showed a strong correlation with DW. There was high collinearity between CD and CA, CD and CV, and CA and CV. However, CV and DSH had a higher correlation with DW than their counterparts, which suggested their use in the model. Therefore, the best allometric equation was: DW = 0.8470*CV − 0.2202*DSH − 1.5315 (R² = 0.99). This equation estimated that F. thonningii produces a very high amount of browsable biomass at all ages compared to common fodder species. The model can be used to plan the browsing rate and understand the ecological role of the species.

Keywords: allometry, indigenous fodder trees, Tigray

African Journal of Range & Forage Science 2012, 29(1): 25–30