Composition and size class structure of tree species in Ihang’ana forest reserve, Mufindi district, Tanzania

Type Journal Article - Tanzania Journal of Science
Title Composition and size class structure of tree species in Ihang’ana forest reserve, Mufindi district, Tanzania
Volume 40
Issue 1
Publication (Day/Month/Year) 2014
Page numbers 1-12
Ihang’ana Forest Reserve is part of the Udzungwa Mountains ecosystem that falls under the
Eastern Arc Mountains (EAM). Previous plant biodiversity studies in this ecosystem concentrated
on large-sized Forest Reserves of greater than 20,000 ha (FR) such as the Uzungwa Scarp
ignoring small-sized forests of less than 300 hectares. This study was therefore undertaken to
assess tree species composition, structure and diversity in Ihang’ana FR (2982 ha), one of the
forest reserves in the Udzungwa Mountains Ecosystem. A total of 7 transects with 12 plots of sizes
20m x 50m each were established for vegetation sampling. Seventytree species representing 32
families and a total of 6478 individuals were identified from Ihang’ana FR. Alpha diversity
ranged between 1.334 and 2.865 (mean 2.246 ± 0.309) with most plots recording species diversity
of greater than 2.014. The most frequent occurring species were Aphloia theiformis (96.4%),
Diospyros whyteana (91.6%), Nuxia floribunda (91.6%) Olea europaea (86.9%) and Macaranga
capensis var. capensis (77.4%). Majority of these species similarly scored the highest Importance
Value Index (IVI) as follows: Aphloia theiformis (112.6), Nuxia floribunda (111.36), Olea
europaea (101.75), Bridelia micrantha (101.25), Diospyros whyteana (98.06), Macaranga
capensis var. capensis (87.62), Morella salicifolia (71.3). M. capensis var. capensis, an indicator
species for disturbance, was poorly represented in the lower DBH size classes, possibly an
indication of forest recovery from past disturbance. Despite reports that licensed timber extraction
used to take place in the forest in the early 1980’s the situation on the ground as observed during
this study shows that the forest has recovered from such disturbance. It is therefore recommended
that the central government continue supporting the local communities around the forest reserve
for example in maintaining fire lanes as part of conservation and management of Ihang’ana
forest Reserve.

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