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Livestock browsing, and illegal harvesting often influence natural woodlands, rangelands, and
biosphere reserves. However, the resulting tree species diversity, composition, and population
structure have rarely been quantified. This study explored the status of tree diversity,
composition, and the growth of Balanites aegyptiaca, across 100 sample plots of 25 m x 40 m at
disturbed and non-disturbed sites in Dinder Biosphere Reserve, Sudan (DBR). The dendrometric
parameters of B. aegyptiaca, fruit production, and the soil-chemical properties were also assessed
in the same sample plots. Moreover, to examine the response of B. aegyptiaca seedlings and
saplings to livestock browsing, the study used a stratified sampling design with four sites been
browsed by goats, cattle, camels, and control, respectively. The study data was collected over
two years from January 2019 to January 2021. It was observed that non-disturbed sites had
double tree diversity than that of disturbed ones (T = 32.6, p < 0.001), and their seedlings and
saplings constituted more than 70% of the entire population (F2,48 = 116.4, p = 0.034; F2,48 =
163.2, p = 0.021, respectively). The soil nitrogen and phosphorus contents beneath trees in non disturbed sites were almost double that of those in the disturbed site (F1, 196 = 68.1, p < 0.001; F1,
196 = 97.9, p < 0.001, respectively) while sodium and electrical conductivity were by about 50%
lower (F1, 196 = 535.8, p < 0.001; F1, 196 = 16.1, p < 0.001, respectively). Mortalities of seedlings
under goat browsing were four times higher than that under camel browsing and control and
twice as high than under cattle browsing (F3,196 = 100.39, p < 0.001). Sapling mortality was three
times higher under goat browsing compared to cattle and control (F3,196 = 73.4, p < 0.001). The
study found that seedlings recover better than saplings, and, unexpectedly, goat browsing
severely affected the natural regeneration of B. aegyptiaca in DBR. Illegal harvesting in DBR
severely reduced tree structure and recruitment parameters of B. aegyptiaca, which might also
impact soil fertility. Intensive monitoring and awareness-raising programs are urgently needed to
conserve this vulnerable tree species. |
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