2.3.3. Social status of D. oliveri and dipterocarps
We used a stratified random sampling design of 40 plots in four
transects and the importance value index (IVI) to determine the
social position of Dalbergia compared to the dominant tree species
throughout the study area. After stratification of the study area into
tentative vegetation types, four representative stands were
selected to assess relative frequency, density and dominance of
each tree species independent of the occurrence of D. oliveri (Fig. 1).
In each stand, a transect measuring 100 m 62 mwas laid out and
subdivided into 20 plots measuring 10 m 31 m to determine the
IVI of species. In each transect, a random sample of ten plots was
drawn by lottery and in each selected plot, trees with a
gbh 14 cm were identified and measured. In each transect, the
IVI for each species was calculated as the sum of the relative
frequency (RF), relative density (RD) and relative dominance
(RDom) (Kent and Coker, 1992).