Assessment of structural framework (tree species dbh and height) of some communal forests in northern cross river state, Nigeria

In view of the consequences of anthropogenic factors such as logging of forest trees for timber and other uses which leads to deforestation, fragmentation and degradation of forest ecosystem and eventually species extinction, this study assessed the structural framework of tree species using diameter at breast height (dbh) (cm) and height (m)in ten communal forests (two each) of the five Local Government Areas (Ogoja, Yala, Bekwarra, Obudu and Obanliku) of Northern Cross River State, Nigeria using the modified Whittaker design as well as diameter and height class intervals. The study was carried out from (November, 2015 – May, 2016). In each site a 30 × 90 m plot was laid out in a spoke design and tree species whose diameter at breast height (dbh) were (≥ 2.5 cm but ≤ 10 cm) for wildlings and 10 cm and above present on the plots were marked, identified, measured and counted. Results of diameter class size of the 352 tree species measured in the study area showed that there were more trees with average trunk size than wildlings (4.35%). Majority of the trees were in the diameter class of 30-39 cm (37.97%) and 20-29 cm (26.96%) with minimum and maximum height classes of 10-19 m (78.12%) and 20-29 m (8.81%). They were however no trees in the higher diameter class sizes of 70-79 cm, 80-89 cm, 90-99 cm and 100 cm and above. This study has therefore given baseline information on the structural framework of trees in these forests and the need for the different stakeholders to take appropriate decisions and measures in sustainable forest management.