The Role of Soil Seed Banks in the Rehabilitation of Degraded Hillslopes in Southern Wello, Ethiopia¹

Abstract

The species composition in the soil seed bank of degraded hillslopes in southern Wello, Ethiopia, was assessed using the seedling emergence method and compared with that of the standing vegetation. Surface soils were sampled at 0‐to 5‐cm depth from 49 plots of four physiognomic vegetation classes (hereafter vegetation classes): forests, shrublands, grasslands, and degraded sites. Soils were spread on sterile sand in a glasshouse and watered. Emerging seedlings were recorded for five months until no new seedlings emerged. A total of 3969 seedlings belonging to 71 species and 30 families germinated. The species composition of the seed bank was dominated by 53 herb species (75%) compared to 2 tree species which accounted for only 3 percent of the total number of species. Seedling density differed significantly among vegetation classes and ranged from 391 to 7807 seeds/m2. Mean species richness also differed significantly among the vegetation classes. Forty‐two species were found to be common to the seed banks and the standing vegetation; however, correspondence between species numbers and composition of the seed banks and the standing vegetation was poor. Although most of the species that germinated in the seed banks were herbs and grasses, they can develop a vegetative cover and contribute to reduction of soil erosion. Regeneration of the tree species (some of which have seed viability up to four years) however, requires both time and the presence of mature individuals. Together with hillside closure and soil conservation measures (e.g., terracing), planting of native woody seedlings might help to expedite rehabilitation of degraded hillslopes devoid of trees and shrubs.

Impact of Cardamom Cultivation on the Composition and Dynamics of Soil Seed Banks in a Conservation Forest in Sri Lanka: Implications for Conservation

“…In addition, many tropical tree species reproduce at irregular supra-annual intervals (Ashton et al, 1988;Connell & Green, 2000;Hart, 1995;Metz et al, 2008) and a lack of synchrony between fruit production of late-successional species and the time when the seed bank was sampled would lead to under-representation of these species in the sample. This combination of factors might explain the low correspondence in the composition of tree species in the soil seed banks and the standing tree community in both CP and NF (Table 1), which is consistent with studies of both disturbed and undisturbed tropical forests (Dalling & Denslow, 1998;Dupuy & Chazdon, 1998;Roberts, 1981;Tekle & Bekele, 2000).…”

“…A comparison of soil seed banks between undisturbed and adjacent degraded forests may contribute to understanding the impacts of disturbance on the density and community structure of buried seeds, and the capacity of soil seed banks to contribute to forest recovery and/or inhibit tree regeneration. Although the soil seed bank is not likely to represent an important source of propagules for regeneration of late-successional trees (Tekle & Bekele, 2000), it may contain a higher density of plant groups, such as pioneer trees, grasses, forbs and non-native species, which may impact future forest composition through competition with newly-emerged tree seedlings (Denslow et al, 2006). Thus this assessment contributes baseline knowledge for designing approaches to the restoration and management of disturbed forests (Butler & Lemenih & Teketay, 2006;Martins & Engel, 2007;Richter & Stromberg, 2005;Wang et al, 2009).…”

The undifferentiated afromontane forest of Denkoro in the central highland of Ethiopia: a floristic and structural analysis

“…Recent studies into the flora and vegetation of South Wello include those that dealt with the ecological rehabilitation of degraded hill slopes (Kebrom Tekle, 1998), flora (Sebsebe Demissew, 1998), and plant population dynamics of selected species (Tesfaye Bekele, 2000).…”

Análise em um Sistema de Informação Geográfica (SIG) das alterações na paisagem em ambientes adjacentes a plantios de pinus no Distrito do Estreito, município de São José do Norte, Brasil

“…A regeneração artificial em áreas perturbadas pode ser melhor planejada se, efetivamente, forem levantadas informações sobre o estado do banco de sementes das mesmas (TEKLE & BEKELE, 2000). A riqueza e abundância de espécies no banco de sementes (associado com a chuva de sementes) contribuem com importantes informações sobre o potencial de regeneração das comunidades (GARWOOD, 1989;WILLIAMS-LINERA, 1993 O Índice de Similaridade de Jaccard não é incondicional e envolve probabilidades estáticas, ao contrário do que ocorre na dinâmica natural, de modo que ele servirá apenas para auxiliar a interpretação dos dados e não para obter conclusões absolutas (LUDWIG & REYNOLDS, 1988).…”