Assessment of population structure, composition and diversity of <i>Dalbergia Melanoxylon</i> in its dominated zone of Nachingwea District, Tanzania

Abstract

Forest management requires up-to-date information on the structure, composition and diversity of populations of plant species. The study was conducted in 2019 on the population status, composition and diversity of Dalbergia melanoxylon to enable sustainable conservation of the species. The community forests of Lionja B and Lipuyu were used to establish 15 plots and 30 plots in Lionja Forest Reserve in Tanzania.The parameters determined include height, stem per hectare, basal area per hectare, density per hectare, tree diameter class and total number of individuals of all species. Most important species were determined using species importance value (IVI) indices. The diversity of plant species was determined using Shannon-Wiener diversity index and compared using ANOVA. The number of stems, basal area and density per hectare was found to be 4.3, 27.2 m² and 483kg/m³ respectively in Lionja Forest Reserve and 1.9, 7.6m² and 350.4kg/m³ in Lionja B community forest. The diversity of plant species of all forms was significantly higher in the forest reserve compared to community forests (P < 0.001). Seventy-one (71) plants have been registered in Lionja Forest Reserve, 51 in Lionja B and 46 in Lipuyu. Plant density in the Lionja Forest Reserve was significantly higher than in community forests. The study found that over exploitation is highly disruptive to forests and, therefore, the study recommends protection, reforestation and restriction of forest resource use due to the importance of the species in the Tanzanian economy.