Comparative quantification of encroacher bush biomass and tree-based evapotranspiration equivalence in encroacher bush-dominated sites of the Kalahari Sands Plateau, Namibia

Woody plant biomass in savanna landscapes exhibits considerable variability; however, biomass variation in African multi-use savannas remains poorly understood. Thus, the study evaluated how areas dominated by encroaching bush species, Senegalia mellifera, Dichrostachys cinerea, and Terminalia sericea, varied in terms of wood quantity, tree equivalence and tree-based evapotranspiration equivalence. The study used a factorial design with two factors (field site and farm), with each farm comprising three field sites, and each field site was dominated by a different encroacher bush species. The Bush Biomass Quantification Tool was used to derive quantitative parameters for the field sites. The study results showed no difference (P > 0.05) in the tree equivalence of sites dominated by different encroacher bush species. However, the Evapotranspiration Tree Equivalence (ETTE) was higher (P < 0.05) in sites dominated by S. mellifera (59,000 ETTE ha–1) compared to those dominated by D. cinerea (17,965 ETTE ha–1) and T. sericea (14,894 ETTE ha–1). Wood quantity was greater (P < 0.05) in sites dominated by S. mellifera (10,095 kg DM ha–1) compared to sites dominated by D. cinerea (6487 kg DM ha–1) and T. sericea (2440 kg DM ha–1). The study concluded that different quantities of wood and bush-feed suitable biomass can be harvested from sites dominated by different encroacher bush species.