Abstract:
This study compared the effects of elephant browsing and response between Acacia
tortilis and A. kirkii in Ruaha National Park. A total of 30 belt transects were randomly
placed in an area of 38.8 km2 on the northern bank of the Great Ruaha River, where 1007
Acacia trees were assessed for elephant damage. Damage was assessed basing on six
browsing categories and four debarking classes. There was no significant difference in
browsing (F1, 10 = 0.6, p>0.05) and debarking (F1, 6 = 0.16, p > 0.05) between A. kirkii and
A. tortilis. Trees were classified into three height classes and twelve diameter classes to
determine population structure. A total of 3613 trees < 1 m in height were recorded to
represent response in addition to coppices; and a significant difference between the two
species was observed only in regeneration potential (F1,58 = 41.4, p < 0.05). Significant
difference was also observed in population structures (F1, 58 = 42.08, p < 0.05). However,
the low regeneration potential, relatively high proportion of severely browsed trees and
restricted distribution of A. kirkii in the study area could make it vulnerable to elephant
feeding than A. tortilis. The high A. tortilis regeneration potential suggests the likelihood
that the area between Msembe and Lunda could become an Acacia bush or woodland if
fire is controlled. The study concludes with recommendations for further studies on the
variation in vegetation utilisation by elephant along the Great Ruaha River, suppressed
regeneration of Acacia trees at Msembe, effects of fire and small browsers on Acacia
species as well as continuous monitoring of vegetation and animal trends.
