Soil seed banks in dry Afromontane forests of Ethiopia

Abstract

Abstract. The soil seed bank was investigated in four dry Afromontane forests of Ethiopia. At least 167 plant species were identified in the 0–9 cm soil layer with total densities ranging between 12 300 and 24 000 seeds/m2. Herbs were represented with the largest numbers of species and seeds in the seed bank, while the contribution of tree species was generally low. The overall vertical distribution of seeds was similar at all sites with the highest densities occurring in the upper three cm of soil and gradually decreasing densities with increasing depth. Relatively high densities also occurred in the litter layer. There were large differences in depth distribution between species, suggesting differences in seed longevity. A large number of species in dry Afromontane forests evidently store quantities of seeds in the soil and this is in contrast to the situation in most tropical rain forests, dry lowland forests and savannas, where both the number of seeds and the number of species are relatively small. It is possible that the strongly seasonal and unpredictable climate of this region may have selected for high levels of dormancy, and that herb regeneration is associated with small scale disturbance. The fact that most of the dominant tree species do not accumulate seeds in the soil suggests that their regeneration from seed would be unlikely if mature individuals disappeared. Most tree species have relatively large seeds and poor long‐distance dispersal; this implies that restoration of Afromontane forests after destruction would be difficult. Since there is a diverse seed bank of the ground flora, this component of the vegetation would have a better chance of reestablishing. However, because most cleared forest land is used for agricultural crop production, it is probable that the seed bank will be depleted in only a few years. Therefore, the future of the Afromontane forest flora seems to depend on the successful conservation of the few fragments of remaining natural forest.

Land Use/Land Cover Change Analysis Using Object-Based Classification Approach in Munessa-Shashemene Landscape of the Ethiopian Highlands

“…Contrary to these and our findings, increase of forest cover was observed by Bewket [22] in Chemoga watershed within the Blue Nile, which was attributed to community afforestation programs. Our change analysis also revealed that planation forests were created at the expense of the remaining natural forest, which belongs to tropical dry Afromontane forests [45]. Cyranoski [63] reported similar conversion of natural forests to planation forests in Indonesia.…”

“…Apart from croplands, the study landscape comprises mosaics of LULC types, mainly natural forests, plantation forests, woodlands, settlements and water bodies. The natural forest in the area belongs to a tropical dry Afromontane forest [45]. The plantation forests are composed of exotic species, mainly Cupresses lusitanica Miller, Pinus patula Schlechtendal & Chamisso and Eucalyptus spp.…”

Factores a Considerar en La Regeneración Natural Del Bosque Tropical Seco en Nicaragua

“…El muestreo en cada sitio incluía cuatro capas sucesivas de suelo separadas, que fueron removidas con la ayuda de un cuchillo filoso y cuchara de jardín, luego la muestra de cada capa se colocó en bolsas plásticas, marcadas con el nombre del sitio, número de línea, número de parcela y capa para llevarlas al invernadero Las muestras incluían la capa de litter y tres capas de suelo mineral sucesivas de tres centímetros de grosor (de 0-3 cms, de 3-6 cms y de 6-9 cms) (Teketay & Granström, 1995). El número de muestras de suelo fueron 48.…”

“…A través del cálculo de la frecuencia se puede tener una idea sobre la distribución que presenta la regeneración de una especie en particular (Matteucii, 1992 Contrario con otros estudios que han reportado valores muy bajos de especies arbóreas almacenadas en el suelo (Gordón, 1999;Scholz et al, 1999;Teketay & Granström, 1995), la proporción relativamente alta encontrada en este estudio de la fracción leñosa, puede relacionarse con la disponibilidad, dispersión y cercanía de la fuente de semillas (Gordón,1999), en especial árboles remanentes. Es posible que muchas semillas de comunidades adyacentes sean dispersadas por aire (anemócora).…”

Distribution, Abundance and Population Status of Four Indigenous Threatened Tree Species in the Arba Minch Natural Forest, Southern Ethiopia

“…Cordia africana and Teclea nobilis are tree species that are categorized under this distribution pattern. These plant species exhibited poor regeneration pattern due to poor stocking, adverse conditions in the forest [38]. These species have smaller value of sapling and this might be due to perishing of seedling before reaching sapling stage [12,17,23].…”