Soil seed bank at an abandoned Afromontane arable site

Abstract

Soil seed bank at an abandoned Afromontane arable site With 5 Figures and 2 TablesS u m m a r y Species diversity, density and spatial distribution of the soil seed bank was investigated at an Afromontane forest site abandoned after clearing and cultivation in eastern Ethiopia. At least 89 plant species were identified in the litter and soil layers down to 9 c m with a total mean density of 11870 viable seeds/m2 (standard error = 3674 seeddrn'). Herbs accounted for 89% of the species and 93% of the total soil seed bank. The share of woody species in the soil seed bank was very low, probably due to the continuous weeding associated with cultivation of crops at the site. Most of the species represented in the soil seed bank are successional species with hard seeds that can withstand and regenerate after disturbances. There were large differences in the spatial distribution between species, suggesting differences in mode of dispersal, seed longevity and predation pressure. Out of the 89 species, 46 species were recorded from only one sample, 41 species from two to nine samples and only two species from all the ten samples. The density of seeds recovered from the ten samples ranged between 2090 and 37 070 seeds/m'. The overall vertical distribution showed a similar I I Feddes Repert. 109 (1998) I -2

Status of Native Woody Species Diversity and Soil Characteristics in an Exclosure and in Plantations ofEucalyptus globulusandCupressus lusitanicain Northern Ethiopia

“…However, these regeneration pathways are reportedly impeded by several limitations. Seed limitation has been reported due to diminished natural vegetation from long-standing deforestation and the confinement of mother trees in churches and remote groves (Wassie and Teketay 2006;Wassie et al 2009), absence of soil seed banks and their depletion by cultivation (Teketay and Granstro ¨m 1995;Granstro ¨m 1997a, 1997b;Teketay 1998;Lemenih and Teketay 2005), and insufficient disperser activity because the seeds of late successional native plants are large, short-lived, and dependent on frugivorous animals for dispersal (Aerts et al 2006(Aerts et al , 2008a. Similar studies also have shown that light, moisture, seed dormancy, and other biotic and abiotic factors limit establishment of late successional tree species.…”

“…Although some of the extremely large trees (,2%; not shown in Figure 1A-C) may be remnants of the original vegetation, the majority are likely to have established from the SSB before the habitat changed much in the plantations. Previous studies have shown that seeds from these 2 species have longer viability and different dormancy mechanisms (Teketay 1998;Wassie et al 2009). Disturbance during plantation-site preparation may break dormancy and trigger germination, and protection from human and livestock would ensure successful recruitment.…”

Abandoned Croplands: Drivers and Secondary Succession Trajectories under Livestock Grazing in Communal Areas of South Africa

“…Communal areas where agricultural cropping land abandonment is concentrated have ruminant livestock production as one of the livelihood sources; therefore, it is imperative to intervene in the secondary succession pattern towards the benefit of livestock production. Allowing the natural succession process to continue with minimal conscious intervention will result in negative environmental and grazing resource impacts such as woody species encroachment [96]. It is therefore critical to manage the abandoned arable land towards a stable vegetation state which favours multi-species ruminant livestock production.…”

Study of the Soil Seed Bank Composition in Arjo-Diga Humid Afromontane Forest under Different Land Use Types and Its Implications for the Restoration of Degraded Lands in Western Ethiopia

“…As a result, 75% of tropical forests are being cleared, degraded, and converted to cropland [6][7][8] and human habitation, which is common in the tropics, e.g., Ethiopia [9,10]. In these cases, while soil seed banks have the potential to recruit regeneration, they are continuously eliminated by weed control and eventually completely depleted [11,12].…”