Aboveground and Soil Seed Bank Woody Flora Comparison in Plantation and Natural Forest, Southern Ethiopia: An Implication for Forest Ecosystem Sustainability

ABSTRACT Forest restoration depends on the availability of seeds in the soils. Understanding relationships between soil seed banks and aboveground flora is vital for framing strategies to ensure sustainable use of forest ecosystems. Human-induced pressures are threatening the natural forests of Southern Ethiopia. The aim of this study was to compare the relationships between aboveground and soil seed bank flora of the plantation and natural forest, Southern Ethiopia. Thirty-nine 20 m by 20 m quadrats were laid along six transects. Woody species with DBH ≥ 2.5 cm were recorded in each quadrat. Overall, 117 composite soil samples were collected from three soil layers of 1 m × 1 m subplots. The soil seed bank was analyzed using the seedling emergence technique. The findings revealed that the aboveground vegetation was represented by 55 woody species, whereas the soil seed bank flora was represented by 31. The seed abundance, species richness and diversity decreased with increasing soil depth. Sorensen’s similarity between the soil seed bank and aboveground flora was low inferring low restoration potential from the SSB in the natural and plantation forests. Therefore, in-situ conservation measures other than SSB alone should be implemented for sustainable development and use of the forest ecosystem.