Woody Species Diversity and Population structure in Solloka Natural Forest, Nonno Benja District, Jimma Zone, Southwest Ethiopia

Abstract

Assessments of woody species diversity and structural analysis studies are crucial for providing information on species richness of the forest and regenerating status which enable developing management strategies for long term resource security. Hence, the study was conducted in Solloka Natural Forest, Nonno Benja District, Jimma zone, Oromia Regional State, South West Ethiopia to investigate the woody species composition of the forest, richness and Diversity, structure and natural regenerating status from May to June 2022. Systematic sampling design was used in the study forest to collect vegetation data from 32 sample quadrats of 20mx20m, 5mx5m for woody species, seedling and sapling respectively at every 50m altitudinal variation. DBH > 2.5cm and height >2m were measured using Tape meter and hypsometer respectively. A total of 71 woody species belonging to 59 genera and 38 families were identified from the studied forest. 40 (56.3%) of the species were trees, 27 (38%) were shrubs and the remaining 4 (5.6%) were climbers. Euclea schimperi was found to be the most frequent (90.6%) species in the Forest. The Shannon diversity index (H’) and evenness (J) of Solloka Forest was 3.6 and 0.84 respectively. The density of mature tree, seedling and sapling was 2785/ha, 2673/ha and 1372/ha respectively. The study realized that the presence of much more small sized woody species in Solloka Natural Forest. The overall basal area of the forest was 54m 2 /ha. Analysis of IVI showed that Olea europea had the highest value (28.7) followed by Euclea schimperi and Syzgium guineense which had 25.15 and 19.05 respectively. Four general pattern of population structure was identified which showed different variations in different DBH and Height class distributions. As analysis indicated 26 (36.6%) woody species showed “good” regenerating whereas 32 (45%), 11 (15.5%), and 2 (2.8%) showed “fair”, “none” and “poor: regenerating respectively but “new” regenerating status of the woody species was not observed in the study quadrats. Complete clearance of the forest, illegal settlement, agriculture and grazing land expansions are the critical problems faced the forest which the concerned bodies should create continuous awareness, using the full knowledge of indigenous people for the sustainable use of forest resources