Diversity and Population Structure of Woody Species Browsed by Elephants in Babile Elephant Sanctuary, eastern Ethiopia: an implication for conservation

Abstract

Babile Elephant Sanctuary (BES), in the semi-arid part of eastern Ethiopia, has long been known
for comprising one of the globally threatened, ecologically isolated and possibly distinctive subsp.
of elephant population (Loxodonta africana orleansi). Study on plant species diversity and
population structure of woody species browsed by elephants in wet and dry seasons was
conducted. A total of 75 quadrats, each 20 x 20 m, were laid out to make the inventory and 24
plant species composed of 16 genera and 13 families were identified. Out of these, trees and shrubs
were represented by 50% each. Total density of the 24 woody species was 11,559 individuals ha-1,
with a mean density of 481.6 ± 282.5 (S.E.). The density of trees was 492 individuals ha-1 (4.3%)
while that of shrubs was 11,066 individuals (95.7%). Total density of seedling and sapling was
3,377 individuals ha-1 (5.5% for trees and 94.5% for shrubs). The population structure of shrubs
exhibited inverted J-shaped structure whereas trees exhibited inverted J-shaped, broken inverted Jshaped,
U-shaped, bell-shaped and broken bell-shaped frequency distributions. These effects are
highly associated with human-induced disturbances, due to population pressure. The result
indicates that BES needs immediate rehabilitation measure in order to ensure the continuous
survival of this, probably, distinctive elephant population.