Abstract:
Impact of land use changes and varying levels of habitat disturbance on tree populations was evaluated
using the spatial analogue technique of studying ecosystem dynamics. Three sites with low, moderate,
and high levels of disturbance were purposively chosen from the Biodiversity Conservation Area
(BCA), an Unprotected Secondary Regrowth (USR), and an Arable Farmland (AF) respectively, for the
study. Tree density and alpha diversity were evaluated in each site. The level of tree species
compositional similarity/variation was also ascertained for each pair of the sites, and the extent of
change in populations of individual tree species measured for the unprotected sites – USR and AF.
Total tree density was highest in BCA (466 trees/hectare) followed by USR (317 trees/hectare) and AF
(73 trees/hectare). Tree diversity was highest and lowest in BCA and AF respectively. Tree species
compositional variation was higher between BCA and each of USR & AF (66.7%), than between USR
and AF (57.1). Harungana madagascariensis, Berlinia grandiflora, and Eleais guineensis were the most
abundant tree species in BCA, USR, and AF, respectively. Although, populations of many tree species
were found to be drastically reduced or completely lost in the unprotected sites, improvement was
observed in populations of few species with Spondias mombin having the highest improvement index
(314.29%) in USR while E. guineensis had the highest improvement index (72.7%) in AF. S. mombin is
highly valued in the study area because of its edible fruits and diverse medicinal attributes while palm
oil and palm kernel oil from E. guineensis contribute immensely to rural livelihoods. Hence, the rural
dwellers tend to favour and encourage their growth.
