Vegetation Structure and Regeneration Status of Woody Species in Gerba Dima Moist Afromontane Forest of Southwestern Ethiopia: Implications for Conservation

Abstract

This study assessed vegetation structure and regeneration status of woody species in Gerba Dima forest, southwestern Ethiopia. Ninety sample plots measuring 25 m × 25 m were laid through a stratified random sampling procedure. The studied forest was stratified into three forest strata based on its altitudinal variation. Stratum I was found at an altitudinal range of 1500−1800 m, while strata II and III were located at altitudinal ranges of 1801−2000 m and 2001−2300 m, respectively. All woody plant species with a diameter at breast height (dbh) equal to or larger than 2.5 cm and a height of at least 1.5 m were recorded. Analysis of the structure of the vegetation was conducted using frequency distribution of dbh, height, and importance value (IV). The regeneration pattern of the study species was assessed by employing the total count of seedlings and saplings. The density of woody species in the study area was 1829 individuals ha−1. Basal area of the Gerba Dima forest was 65.05 m2ha−1. Total densities of seedlings, saplings, and trees/shrubs were 4558 ha−1, 2149 ha−1, and 1515 ha−1, respectively. Structural analysis and assessment of the regeneration status of woody species in the Gerba Dima forest showed that the overall ecological condition of the forest was healthy as indicated by inverse J‐curve dbh distribution, which showed a large number of individuals in lower dbh classes. Furthermore, a large number of seedlings and saplings were recorded for most species, in addition to the presence of a sufficient number of matured trees. However, some species exhibited abnormal population structure and abnormal patterns of regeneration characterized by fewer or no individuals in lower dbh, as well as in seedling and sapling stages. It was thus concluded that species with abnormal population structure and regeneration status (e.g., Sapium ellipticum and Trichilia dregeana) require urgent conservation attention.