Tree species composition, structure and utilisation in Maruzi Hills Forest Reserve in Uganda

Abstract

The study investigated the tree species composition, vegetation structure and harvesting pattern to guide management of the Maruzi Hills Forest Reserve. Stratified random sampling was used to site six (100 m × 100 m) permanent sample plots in the woodland, bushland and grassland vegetation types identified in the reserve. Rényi diversity profiles indicated that bushland vegetation had a lower Shannon diversity index (H = 2.054) than grassland (H = 2.38) and woodland vegetation (H = 2.319). Grassland and woodland vegetation also had lower proportions of the dominant species (α_∞ = 1.15 and 1.66, respectively) than bushland vegetation (α_∞ = 3.25). However, the mean stem density of the woodland, bushland and grassland vegetation was 214 stems ha^-1, 191 stems ha^-1 and 114 stems ha^-1, respectively. Bray-Curtis and Jaccard ecological distance matrices showed that, although the three vegetation types shared some common species, the ecological distances were relatively high suggesting significant species composition variation between the vegetation types, particularly between the bushland and the other vegetation types. The species with the highest proportional abundance in the survey were Combretum molle (23%), Acacia hockii (17.7%), Combretum collinum (16.1%), Grewia mollis (6.5%) and Lannea barteri (6.5%). Diameter size-class distribution of woody perennials and tree stumps indicated higher frequencies of the smaller-diameter size classes. The stump records were indicative of charcoal burning and firewood collection as major causes of tree/shrub harvesting. The Maruzi Hills woodland conservation strategy should consider the differences in species composition between vegetation types if the highest number of species is to be conserved.

Keywords: diameter class distribution, species diversity, stump characteristics

Southern Forests 2010, 72(2): 112–116