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Universität zu Köln (2009)

Rangeland use in Northwestern Namibia . An integrated analysis of vegetation dynamics, decision-making processes and environment perception

Eisold, Jenny

Titre : Rangeland use in Northwestern Namibia . An integrated analysis of vegetation dynamics, decision-making processes and environment perception

Auteur : Eisold, Jenny

Université de soutenance : Universität zu Köln

Grade : PhD thesis 2009

Résumé partiel
Degradation of natural resources has become a serious challenge in rangelands, bearing negative impacts on the pastoral ecosystems, livestock production and livelihoods. In Namibia, the driest country of sub-saharian Africa 45 per cent of the national land area can only be used as rangeland. Many Namibians are pastoralists, whose livelihoods mainly depend on natural rangeland vege-tation and water resources. 43 per cent of Namibia�s land surface is used by 90 per cent of the population under communal land tenure. This socio-economic importance makes the sustainable use of the rangeland essential. Furthermore northern Namibia will be heavily affected by climate change. Integrating local and scientific environment perception, decision-making proc-esses of the local land users and the impact of land use practices on vegetation dynamics into ecological research becomes increasingly important in today�s complex web of social, ecological and political changes. This thesis develops an integrated approach focusing on ecological aspects in a social-ecological rangeland system in Northwestern Namibia. Firstly I developed a methodological approach for the synthesis of local eco-logical knowledge (LEK) and scientific knowledge. I found that to local live-stock herders, woody species are more important than herbaceous species, what does not correlate with species� ecological performance in the grazing area. I hypothesise that reliability of forage resources in times of scarcity is important in local perception. This shows that integrating LEK on ecological items into ecological research helps to identify criteria, or indicators for local management decisions. In the second step I matched local knowledge and local management decisions. In dealing with scarce and variable natural resources it is crucial to acquire a functional understanding of the interactions between management strategy and the mechanisms which buffer the variability of rainfall. I differentiated between abiotic buffers (key resource areas) and biotic buffers (storage tissue and stockpiled forage). The two biotic buffer mechanisms can be managed via herd mobility. I analysed how mobility is connected to the supply of the eco-system goods �water� and �forage�. I related the mobility decisions of local herders to the biotic and abiotic buffers of pastures used to see if they made use of pastures with key resource properties. In the communal areas, the main decision factor for mobility was permanent water availability and herders mainly follow short-term management objectives. Their set of options may be limited by influences that go beyond ecological conditions, such as land pres-sure, a non-adapted institutional framework and limited options for sustaining their livelihoods. This section shows that to grasp the essential elements of range management it is important to understand user objectives in deciding when and where to move in times of scarce resources. Reliability, which is perceived as an important criterion for the quality of for-age resources, has a lot in common with the concept of key resources, which are defined as forage resources available in times of resource scarcity. While other authors have a descriptive approach to the reliability of key resources, I functionally defined them as biotic and abiotic buffers. Mots clés : savanna, rangeland management, local knowledge, buffer, degradation

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