Compositional gradients in plant species distribution patterns and genetic diversity of scorodophloeus fischeri thub in selected coastal forests, Tanzania

Tanzanian coastal forests are a heterogeneous group of isolated forests which are part of 34 global biodiversity conservation hotspots. Despite their biodiversity value, disturbance caused by human activities is high and little was known about the ecology of coastal forests, genetic diversity and regeneration potential of Scorodophloeus fischeri. This study determined levels of disturbance, the influence of soil nutrients on plant species distribution patterns in three coastal forests of Tanzania. Also, natural regeneration potentials of Scorodophloeus fischeri were assessed and compared the genetic diversity within and among S. fischeri populations. Canonical Correspondence Analysis (CCA) showed high species-environmental correlation implying that soil nutrients determined plant species distribution patterns in coastal forests. However the influence of soil nutrients in combination with disturbances on vegetation communities is synergistically. S. fischeri regenerated best in undisturbed parts of the forest with high recruits than disturbed forests. 60% genetic variability occurred within and 40% among S. fischeri populations. The genetic differentiation (Gst) among populations was 0.252, with low gene flow (Nm = 2.301) among S. fischeri populations. It was concluded from this study that, in forests that are relatively undisturbed S. fischeri regenerated better than in disturbed forests. Also the soil nutrient elements significantly influenced plant species distribution patterns in undisturbed forests but in the severely disturbed forests were not significant. Low gene flow among populations implied that S. fischeri populations in the coastal forests are isolated, and hence all forests studied are of high conservation significance.