Abstract:
It is critical to understand how forests regenerate
after the exclusion of human induced disturbances because
the regenerating species drive the renewal of resources and
ecosystems, which in turn support human beings locally
and globally. This study of forest regeneration was conducted
in the tropical coastal forest ecosystems of Tanzania
at Uzigua Forest Reserve (24,730 ha) in the Pwani Region.
We collected data from adult trees in 47 sampling plots
(25 9 25 m) randomly established in closed forest sites
(control) and in sites disturbed by farming and livestock
grazing. Sapling and seedling data were collected and
analyzed in 2 9 2 m nested subplots. Plots in the closed
forest had higher mean basal area and volume for adult
trees than those in sites disturbed by farming and livestock
grazing. Plots in sites disturbed by farming had the highest
Shannon–Wiener index for seedlings and saplings, followed
by closed forest and livestock grazed sites. Closed
plots and farmed plots had higher Simpson’s index for
seedlings and saplings than in grazed sites. Plots in farmed
and livestock-grazed sites had a higher Simpson index for
adult trees than in closed sites. Equitability of seedlings
and saplings was highest in closed forest sites, followed by
farmed and livestock grazed sites. Plots disturbed by
farming had higher equitability for adult trees than in
livestock-grazed and closed sites. Moreover, plots disturbed
by farming and grazing had a higher importance
value index for seedlings than in closed sites. Plots in
closed forests had higher sapling importance values than in
farmed and grazed sites. Again, plots in closed forest had a
higher importance value for adult trees than in farmed and
grazed sites. The differences in tree species subcategories
of regeneration across land-use indicates that farming and
livestock grazing disturbances create heterogeneous
microhabitats, which positively or negatively affects
regeneration capacity of species after exclusion.
