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Universidade de Lisboa (2019)

Drivers of small mammals’ abundance patterns in a South African landscape : the contexts of management intensity and functional groups

Afonso, Beatriz Cardoso de Matos

Titre : Drivers of small mammals’ abundance patterns in a South African landscape : the contexts of management intensity and functional groups

Auteur : Afonso, Beatriz Cardoso de Matos

Université de soutenance : Universidade de Lisboa

Grade : Mestrado, Biologia da Conservação 2019

Résumé partiel
In the past, the extinction of species was the result of a natural process that occurred without any intervention by Man. However, the increase in extinction rate of species in the Anthropocene is mostly of human cause. One of the planetary boundaries that humanity has already exceeded is biodiversity loss (Rockstrom et al. 2009) due to activities such as deforestation, overfishing and overgrazing (Vitousek et al. 1997 ; Chapin et al. 2000). All these activities have an impact on habitat as they lead to land use change, due to habitat degradation and conversion (Vitousek et al. 1997).Consequently, species loss leads to the reduction of ecosystem services and functions efficiency on which humans depend (Sala et al. 2000 ; Cardinale et al. 2012 ; Mace et al. 2012). For example, reducing herbaceous stratum negatively influences small mammals as they rely heavily on vegetation for shelter and food, which in turn can reduce the effectiveness of the nutrient cycle, as small mammals actively contribute to the nitrogen cycle through their faeces (Bakker et al. 2004, Clark et al. 2005). In Africa, over recent decades, major changes in land use have occurred due to increase in deforestation and grazing areas (Stephenne and Lambin 2001). Most landscapes have been converted to cattle ranches, farmland and urban settlements, leading to a decline in natural ecosystems (Maitima et al. 2009). The decentralization of public conservation policies in South Africa gave landowners rights over wildlife (Pitman et al. 2016) which led to the conversion of former land uses into wildlife-related activities such as game ranches and private reserves for ecotourism. Each of these types of management has different objectives, which induce different consequences on the ecosystem. While in farms, the main objective is to maximize the production of ungulates meat, in private reserves the focus is on the conservation of the natural heritage, with the aim of maximizing the profitability of exploration through the attraction of hunters and tourists whose presence and activities support the cost of maintaining a habitat as natural as possible, foster the presence of charismatic and highly valued animals such as the so-called “Big 5” - Elephant, Rhino (Black and White), Buffalo, Lion and Leopard. Coexisting with these two types of landscape management, rural areas can be found in southern Africa, which include not only urban settlements but also areas devoted to agriculture and livestock, thus having the highest human population density and abundance of domestic livestock, compared to other land uses (Parsons et al. 1997). Small mammals are critical to the proper functioning of the ecosystem as they contribute to various ecosystem services (Avenant and Cavallini 2007). Being primary consumers (Avenant and Cavallini 2007) makes them vital links in structuring the food chain (Cameron and Scheel 2001) as they consume plant material and in parallel support a large community of predators, from birds to mammals (Anderson and Erlinge 1977)

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