Population Structure And Phenology Of The Selected Indigenous Tree Species In Moist Evergreen Afromontane Forests Of South West Ethiopia

Abstract

Understanding the population structure, regeneration status, and phenology of indigenous tree species in natural forests is a basic requirement for establishing in-situ seed production sites and introduce appropriate management options. The aim of this study was, therefore, to investigate the population structure and regeneration status and reproductive phenology of Prunus africana, Pouteria adolfi- friedericii and Milicia excelsa. This study was conducted in four Afromontane forests such as Yayu, Bonga, Bebeka, and Masha, south west Ethiopia. For this, systematic sampling method was used to collect the data and accordingly, from each site ten transects of 160m long were laid out at 100 m interval along slope gradient and quadrats (size: 20 m x 20 m each) were laid at 50m interval along each transect line. In total 270 quadrats were used for vegetation data collection. To collect data on regeneration, sub sample quadrats (size: 5 m × 5m each) were established at four corners and at the center of each of the main quadrats. From each main quadrat, DBH and total height of the three study tree species were measured using a diameter tape and clinometer respectively. The results of the distribution of the population of P.africana showed broken J-shape and irregular patterns across the forests; Pouteria adolfi‑ friedericii exhibited irregular and broken inverted Jshape across the forest sites; the shape of the structure for Milicia excelsa tree species observed in sampled forests was almost irregular. The regeneration status of P. africana is “good” in Bonga and Masha and “fair” in Yayu sampled natural forest; for P. adolfi‑ friedericii is “good” in Masha and “fair “in Bonga and Yayu, and it is “fair” and “none” in Masha and Yayu sampled natural forests for M. excelsa tree species. The result of the phenology assessment indicated that the times of flowering and fruiting generally ranges between December and June across the forest sites. Overall, the population structure of the studied tree species vary and also similar in some cases across the inventoried forest sites. There is a slight variation in phenology among sites showing the essence of exhaustive description of these parameters prior to the establishment of the seed provenances and domestications for the desired populations of the indigenous tree species.