Effect of Mixed plantation on growth performance and above ground biomass of Eucalyptus globulus in highland area of central Ethiopia region

Abstract Monoculture plantations, particularly of Eucalyptus species, have faced criticism for their negative environmental impacts and limited contributions to biodiversity and local livelihoods. Mixed-species plantations are promoted as a more sustainable alternative, yet their adoption remains limited. This study evaluated the early-stage growth performance, yield, and aboveground biomass of E.globulus in mixed plantations with four indigenous and exotic tree species— H. abyssinica, P. falcatus, C. lusitanica , and J. procera —in the highland area of Gummer district, central Ethiopia. A randomized complete block design with three replications was used, and data on height, diameter, survival, biomass, and carbon density were collected over four years. Results showed no significant negative effects of mixing on E. globulus growth, survival, or biomass accumulation compared to monoculture. Mixed stands, particularly those with J. procera and C. lusitanica , showed numerically higher growth rates and relative yields. Aboveground biomass and carbon density of E. globulus were comparable across treatments, while companion species contributed additional biomass, enhancing overall stand carbon stocks. The findings suggest that mixed-species plantations can serve as a viable alternative to monocultures without compromising the early productivity of E. globulus .