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A proposed rural water supply scheme in the northern Oshikoto Region will impact on the settlement patterns of the rural population. For this reason an environmental impact assessment was commissioned. In this paper the degradation gradients found in the oshana system in the western part of the study area are discussed. Degradation is not only due...
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... study area consists of a 30 km wide strip north of the tarred road between Tsumeb and Ondangwa (B1) from 17° East up to Okatope, as well as a 5 km south of the road (Figure 1). This paper deals with the western-most part of the study area, the Hyphaene petersiana plains of the Oshana system. ...
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A proposed rural water supply scheme in the northern Oshikoto Region will impact on the settlement patterns of the rural population. For this reason, an environmental impact assessment was commissioned. In this paper the degradation gradients found in the shrublands on the eastern fringe of the oshana system, dominated by Colophospermum mopane, are...
A proposed rural water supply in the northern Oshikoto Region will impact on the settlement patterns of the rural population. For this reason an environmental impact assessment was commissioned. In this paper the degradation gradients found in the broad-leafed savannas in the eastern part of the study area are discussed. Degradation is mainly due t...
Citations
... Cynodon dactylon is widespread in Namibia and is generally regarded as a sub-climax grass in the northeastern and north-central parts of the country (Strohbach, 2000). However, little is known about C. dactylon in north-central Namibia. ...
In north-central Namibia, pearl millet cultivation is critical for the subsistence of the local people. In recent years, pearl millet cultivation affected by Cynodon dactylon has been observed in the area. In this study, we examined the background and impact of C. dactylon on agriculture in this region. Our study showed that there would be almost no pearl millet harvest if C. dactylon dominated the fields. The distribution of C. dactylon was spatially skewed within the region, and the degree of weed damage varied between households. Analysis of the distribution of C. dactylon and the land characteristics of each household revealed that the indigenous land unit and the year in which the local people migrated were influential factors. The expansion of C. dactylon is an agronomic problem and is affected by several factors, including the human community structure, diversity of the natural environment, and recent social changes.
... We know of no work on the influence of elephant herbivory on ivory palm, but high densities of livestock in north-central Namibia were responsible for a high proportion of palm leaves being damaged at levels considered unsustainable (60%-98% in various size classes; Konstant et al., 1995;. In the same region, Strohbach (2000) reported the disappearance of ivory palms along a degradation gradient due to overgrazing by livestock. Although we did not record damage to ivory palm leaves, observations while sampling indicated that relatively low proportions of leaves were damaged, but by which large herbivore is uncertain. ...
African elephants have major impacts on vegetation, particularly at high densities. Knob‐thorns ( Senegalia nigrescens ) are typically ring‐barked by elephant, and high levels of mortality are common at high elephant densities. Our study aimed to test whether ivory palm clusters ( Hyphaene petersiana ) form a biotic refuge for knob‐thorn against elephant herbivory. We measured the density, damage and mortality of knob‐thorns in sites differing according to ivory palm presence and elephant density, and thus, the probability of knob‐thorn encounter by elephants. The site with palms and low elephant density, had a high density of knob‐thorns, but lower proportions of damaged and dead trees, than sites without palms but with similar or higher elephant density. In the former, knob‐thorns were associated with palm clusters, particularly saplings and young adults. In this site, low proportions of damaged and dead knob‐thorns were recorded in palm clusters, compared with outside clusters, and to those in the other sites. Our study also showed that juvenile palms which protected knob‐thorns, suffered low mortality in contrast to subadult palms. We have no evidence but implicate elephants and suggest that in palm clusters, subadult palms are more accessible to elephants than knob‐thorns because of the different methods of utilisation.
... Deforestation is largely linked to population growth and the felling of trees either for firewood or for construction. Recently, the construction of the central pipeline system and the subsequent year-round availability of drinking water for livestock has further increased the pressure on the ecosystem and accelerated degradation trends (Strohbach, 2000). ...
... Deforestation is largely linked to population growth and the felling of trees either for firewood or for construction. Recently, the construction of the central pipeline system and the subsequent year-round availability of drinking water for livestock has further increased the pressure on the ecosystem and accelerated degradation trends (Strohbach, 2000). ...
... • Deforestation: In stark contrast to the increase of woody plants referred to as bush encroachment in central and southern Namibia is the severe reduction of woody cover in the northern communal areas through overutilization of these resources and lately also slash and burn agriculture (Kreike 1995;Strohbach 2000aStrohbach , 2000bErkkilä 2001;Klintenberg et al. 2007;Pröpper et al. 2010). In order to undertake conservation measures and to restore the degraded land, good baseline data on the species composition is essential. ...
Aims: The usefulness of phytosociological descriptions is often not recognised by land use planners and -managers, as these do not provide much information useful for their purpose. With this paper a "Suitability Index" is introduced to illustrate the suitability of natural vegetation types for extensive livestock farming (being one of the main land uses in Namibia), in order to make the vegetation maps and descriptions more user-friendly. Methods: Relevé data are compiled on standardised plots throughout the country, with a standardised set of environmental parameters. In addition, a range of additional data are extracted from GIS-based data sources via the plot position. From these data, the Suitability Index is calculated. It consists of three sub-indices, related to habitat, structure and composition. The habitat sub-index determines the plant growth potential, but also some management options and/or constraints. The structure sub-index is based on the cover of perennial vs. annual grasses, shrubs and trees, as an indicator for ecosystem health. The composition sub-index takes the presence of toxic plants and the palatability of grasses into account. From the sum of these sub-indices, a categorical rating is derived to describe the suitability of the vegetation for extensive livestock husbandry. Results: The Suitability Index is demonstrated by way of worked examples for four widespread Namibian vegetation associations ranging from sub-humid woodland savannahs to desert grasslands. The results correspond well with a widely used, but outdated grazing capacity map. Conclusions: The Suitability Index presents a major value addition to vegetation descriptions. However, it does not replace an accurate determination of grazing capacity, mainly because it is derived from plant cover estimates, and because surveying of the vegetation is generally limited to one season. The composition sub-index can be greatly enhanced once browse availability data for shrub and dwarf shrub species become available.
... Close to the road and around settlements, trees had been cut for the production of charcoal, beehives, and fencing materials. Similar degradation trends of savannah vegetation close to settlements were reported in Namibia (Strohbach 2000). In areas where temporary or permanent crop fields had been established, most of the natural vegetation had been cleared. ...
Crop cultivation under rain-fed conditions is a recent innovation among the formerly pastoral-nomadic Pokot in north-central Kenya. We have examined the socioecological dynamics of land-use change from an interdisciplinary perspective. The patterns of transition to agropastoralism are closely related to both the biogeophysical attributes of the area and the economic characteristics of the households. While the use of advanced agronomic practices in the highlands is associated with annual maize grain yields of >2 Mg ha−1, unfavorable climatic and edaphic conditions, as well as the limited agronomic knowledge of the newcomer farmers in the lowland and mid-hill zones, make field crop production there an opportunistic, spatially scattered, and rather erratic land-use strategy. The accelerated transition to crop cultivation and the spatiotemporal differences in sedentarization between zones contribute to a fragmentation and shortage of land, which results in growing interhousehold inequalities and increasing conflicts within Pokot society.
... The distribution of acacia has a pattern similar to the distribution of the Owambo kingdoms (Fig. 2), implying that this vegetation was cultivated by people. Previous studies have demonstrated that this vegetation formed as a result of bush encroachment (Mendelsohn et al., 2000; Strohbach, 2000) and that the overuse of mopane timber by the Owambo led to vegetation degradation (Erkkilä & Siiskonen, 1992; Erkkilä, 2001). Thus, vegetation varies between the center of the kingdom and the frontier because of the historical impact of the uses of vegetation at the center of the kingdom. ...
Agro-pastoralists living in arid lands of Africa tend to have highly mobile lifestyles and to use natural resources widely and sparsely. Thus, they require frontiers with low population densities and sufficient natural resources. However, this study found that the enclosure of the local frontier has prompted social changes, such as the setting of conservation areas and the construction of new villages. The aim of this study was to clarify how Owambo agro-pastoralists living in north-central Namibia have changed their use of natural resources in response to transformations to the local frontiers they inhabit. The Owambo group consists of a number of subgroups. Some of these groups formed small kingdoms; most group members live at the kingdom's center surrounded by the frontier at the periphery. Since the 1970s, other people have migrated into these frontier areas and altered the local conditions, forcing inhabitants to change their use of natural resources. Local inhabitants have coped with this situation in three main ways: (1) wealthy people have established private cattle posts in the frontier where they graze their livestock and gather natural resources, (2) some (especially non-wealthy people) have started to use indigenous fruit trees in multiple and intensified ways, not only for their fruit but also as building materials and wood for fuel, and (3) older villagers have established social networks with newer villagers on the frontier to exchange goods that are available only from their respective areas. The progress of people who can access the natural resources in the frontier has been limited by the enclosure of the local frontier. However, local customs involving the reciprocal exchange of surplus natural resources among neighbors and neighboring areas remain and have been adapted in response to the new situation.
... However, Mendelsohn et al. (2000) discovered several patches of vegetation that were dominated by Acacia arenalia, which belongs to the family Mimosaceae. Previous work has demonstrated that this vegetation has formed as a result of bush encroachment (Mendelsohn et al., 2000; Strohbach, 2000). Ovambo agro-pastoralists primarily inhabit this region, and they use several tree species for various purposes, similar to other southern African societies. ...
This paper focuses on the mutual transition between vegetation and timber use by the Ovambo people in north-central Namibia and their use of palms for timber in recent years. The vegetation around the research area was characterized as Mopane savanna, dominated by Colophospermum mopane. Historically, the Ovambo used mainly Mopane trunks for timber. However, as bush encroachment advanced in some parts of north-central Namibia, residents were forced to collect Mopane timber from the south. Since the 1970s, however, collecting Mopane has become difficult, and the inhabitants have therefore begun to use palm petioles for timber. Because the use of this resource requires many palm petioles, an environment conducive to grow many palms is required to make this option feasible. The vegetation configuration of this environment was formed mainly by three factors: (1) the unique fl ood terrain initially dispersed palm seeds over a wide area, (2) humans involuntarily dispersed seeds after eating, (3) palms were conserved by the residents. Thus, the increased use of palms emerged at a point of intersection between a change in vegetation patterns and a change in plant use by humans. The critical points of this use are its sustainability and the maintenance of traditional building complexity.
... The study area consists of a strip 30 km wide north of the tarred road between Tsumeb and Ondangwa (B1) from 17° East to Okatope, as well as a 5 km south of the road. This paper deals with the transition between the oshana system to the west and the broad-leafed savannas to the east and north (seeFigure 1 in Strohbach 2000a). To note: whilst the transition to the Andoni plains is abrupt, the transition to the Broad-leafed savanna is often gradual. ...
A proposed rural water supply in the northern Oshikoto Region will impact on the settlement patterns of the rural population. For this reason an environmental impact assessment was commissioned. In this paper the degradation gradients found in the Terminalia prunioides woodlands, being a transition between the Broad-leafed savannas to the north and east and the Andoni plains of the Etosha basin to the south, are discussed. Degradation is typically associated with deforestation as well as overgrazing and trampling. Although a classification is given on various species' reaction to degradation i.t.o. decreasers and increasers, this is to be seen preliminary and to be used with caution.
... The study area consists of a strip 30 km wide north of the tarred road between Tsumeb and Ondangwa (B1) from 17° East to Okatope, as well as a 5 km south of the road. This paper deals with the transition between the oshana system to the west and the broad-leafed savannas to the east and north (seeFigure 1 in Strohbach 2000). ...
A proposed rural water supply scheme in the northern Oshikoto Region will impact on the settlement patterns of the rural population. For this reason, an environmental impact assessment was commissioned. In this paper the degradation gradients found in the shrublands on the eastern fringe of the oshana system, dominated by Colophospermum mopane, are discussed. Degradation is mainly due to deforestation by the over-utilisation of wood. Although a classification is given on various species' reaction to degradation in terms of decreasers and increasers, this is to be seen as preliminary and to be used with caution.
