Assessment of illegal forest activities on plant diversity in Tano Offin globally significant biodiversity area (GSBA) in the Nkawie Forest District, Ghana
Biodiversity in all forms sustains tremendous socio-economic and cultural interests of millions of people all over the world. Increasing human population has resulted in proportional increase in the demand for natural resources for the sustenance of human development needs. It is based on this, that the study was conducted in the Globally Significant Biodiversity Area (GSBA) within the Tano-Offin forest reserve. The aim of the study was to assess the extent of human activities and its effects on the tree community in the GSBA, with specific objectives of measuring the quantum of human activities occurring in the GSBA, examine the effect of unwanted human activities on tree species richness, abundance and diversity in the GSBA, and also examine the impact of the unwanted human activities on tree species composition, basal area and relative dominance. The area was stratified into two, thus, disturbed and undisturbed areas. In each of the stratified areas, a total of 5km transects were established. On the transects, 20m x 20m plots were laid at every 200m, for 5km. The disturbed area was identified by unwanted human activities such as farming, chainsawing and charcoal production. Trees were enumerated at both areas. Moving in clockwise direction within a plot, all trees with diameter at breast height (1.3m from the ground) equal to or greater than 10cm (≥ 10cm dbh), were identified, measured and recorded. The diameter at breast height of each sampled tree was measured over bark with diameter tape. The mean number of trees identified and recorded in the areas affected by unwanted humans activities was 12.8 (SD=4.2, N = 25), while that of the undisturbed areas was 20.1 (SD=4.3, N=25), Mann- Whitney test shows that there was significant difference between the trees found in the disturbed and the undisturbed areas at p< 0.05 (U = 80, p = 6.749E-6). Shannon-Wiener’s diversity index indicates that the diversity of trees in the areas affected by illegal activities was 3.164 and that of the undisturbed areas was 3.194. The t-test shows that the diversity of trees in both areas were not significantly different (t =1.7985, p = 0.072674).
A thesis submitted to the Department of Environmental Science, Kwame Nkrumah University of Science and Technology, Kumasi in partial fulfillment of the requirements for the Master of Science Degree in Environmental Science, 2013