Abstract
This study was conducted to determine woody tree species biodiversity in Aliero Local Government, Nigeria. The Point-Centred Quarter Method (PCQM) was used to enumerate the tree species in the study area. Ten (10) transects of 1 km length each was cut in each of the survey area (Aliero, Dan Warai and Sabiyal District). Out of the ten (10) transects, three (3) were randomly selected in each survey area. These transects were pegged at 100m interval and the point centre quadrant dropped systematically at these points which gave a total of 30 sampling points. Only trees of 1m and above in height nearest to the sampling point in each quarter of the quadrant were enumerated and recorded.A total of 2,682 woody tree species were encountered in the Local Government. Guiera senegalensis and Mimosa pigma recorded the highest frequency of 481 and 242 respectively while Anogeissus leiocarpus, Albiziachevalieri, and Celtiszenkeri recorded the lowest frequency of 2, 2 and 4 respectively. Data obtained from tree species composition were analysed using the tree species Shannon Weinner Biodiversity Index. A higher species biodiversity of 3.095 was observed in the study area. Although, the study area shows a higher biodiversity in terms of number of tree species available, species relative proportion is very small. Therefore, enactment of environmental laws associated with conservation and preservation of woody species in the study area for sustainability is recommended. Also Non-Government Organizations (NGOs) and Community Based Organizations (CBOs) should be encouraged to take active part in community forestry activities in order to reduce the pressure on the present forest tree species and increase their proportions.

Key words: Woody tree Species, Biodiversity Index, Point Quarter Centre Method (PCQM)