Eleven sites including treefall gaps and surrounding shades (under canopy) werernstudied in the Shashemenne-Munessa natural forest to investigate the dominance,rnfrequency, density and overall importance of established seedlings and saplingsrnof high forest tree species. Examination of the established seedlings and saplingsrnof tree species in the gaps showed that Croton lIlacrostachyus, Rapanearnmelanophloeos, Maesa lanceolata, Podocmpusjalcatlls and Vernonia auriculijerarnconstitute the most important species in the gaps studied. Croton macrostachyusrnwas found to have the highest percentage value as overall and definitive gapfiller,rnwhereas, Maesa lanceo[ata, Podocmplls jalcatlls and Juniperus procera werernfound to be the most important gapmakers. These gapmakers constituted 76% ofrnthe canopy composition in the Shashemenne-Munessa natural forest. Thernreplacement proportions in gaps were examined to assess their role in the forestrncommunity and no evidence was found to support self or reciprocal replacement.rnThe gapmakers-gapfillers comparisons indicated preferential replacement ofrnahnost all species by Croton lIlacrostachyus, suggesting that the community isrnundergoing successional change. No significant correlations were found betweenrnthe gapmakers and gapfillers, canopy composition and gapfillers, gap size andrndominance as well as importance values of species. However, statisticallyrnsignificant correlations were found betw.ecn species'cbtniJ,ositioh, a*4 gaRsi,2;~ iulrnMay tenus addat, Rapanea lIlelanoph'toeos, DOJlyalis, ,abyssinica,. ,Bersamt1'rnabyssinica and Teclea lIobilis could be categorized as climax species, whereas,rnJuniperus procera, Maesa lanceolata, Vernonia auricillijera and Crotonrnrnmacrostachyus could be classified as forest pioneer species. Furthermore, therndiversity of tree species was found to be greater in the gaps than under the closedrncanopy.