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| 2. |
- Aarrestad, P. A., et al.
(author)
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Influence of soil, tree cover and large herbivores on field layer vegetation along a savanna landscape gradient in northern Botswana
- 2011
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In: Journal of Arid Environments. - : Elsevier BV. - 0140-1963 .- 1095-922X. ; 75:3, s. 290-297
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Journal article (peer-reviewed)abstract
- The response of the field layer vegetation to co-varying resource availability (soil nutrients, light) and resource loss (herbivory pressure) was investigated along a landscape gradient highly influenced by elephants and smaller ungulates at the Chobe River front in Botswana. TWINSPAN classification was used to identify plant communities. Detrended Correspondence Analysis (DCA) and Canonical Correspondence Analysis (CCA) were used to explore the vegetation-environment relationships. Four plant communities were described: Panicum maximum woodland, Tribulus terrestris woodland/shrubland, Chloris virgata shrubland and Cynodon dactylon floodplain. Plant height, species richness and diversity decreased with increasing resource availability and resource loss. The species composition was mainly explained by differences in soil resources, followed by variables related to light availability (woody cover) and herbivory, and by interactions between these variables. The vegetation structure and species richness, on the other hand, followed the general theories of vegetation responses to herbivory more closely than resource related theories. The results suggest a strong interaction between resource availability and herbivory in their influence on the composition, species richness and structure of the plant communities.
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| 3. |
- Aarrestad, P. A., et al.
(author)
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Vegetation : Between Soils and Herbivores
- 2014
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In: Elephants and Savanna Woodland Ecosystems. - Chichester, UK : Wiley-Blackwell. - 9781118858615 - 9780470671764 ; , s. 61-88
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Book chapter (peer-reviewed)abstract
- The vegetation of the study area in Chobe National Park is influenced by a range of factors, including inundation by the Chobe River, soil moisture and fertility, and the impacts of different-size grazers and browsers. This chapter focuses on how the structure and species composition of the present vegetation in northern Chobe National Park is related to recent herbivory by elephants, as agents shaping the vegetation, and by mesoherbivores acting as controllers or responders, along with abiotic controllers such as soil type and distance to the river. In the study, a two-way indicator species analysis classified the vegetation data into four more or less distinct plant community groups (i) Baikiaea plurijuga-Combretum apiculatum woodland, (ii) Combretum mossambicense-Friesodielsia obovata wooded shrubland, (iii) Capparis tomentosa-Flueggea virosa shrubland and (iv) Cynodon dactylon-Heliotropium ovalifolium floodplain, named after the TWINSPAN indicator or preferential species with high cover, and the relative amount of shrubs and trees.
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| 4. |
- Skarpe, C., et al.
(author)
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Historical Changes of Vegetation in the Chobe Area
- 2014
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In: Elephants and Savanna Woodland Ecosystems. - Chichester, UK : Wiley-Blackwell. - 9781118858615 - 9780470671764 ; , s. 43-60
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Book chapter (peer-reviewed)abstract
- Elephants are the main agent shaping the vegetation (substrate), whereas soil properties and, at a larger scale, climate constitute major controllers of elephants' activities and of their effects on vegetation. However, elephants have not been the only agents of change in the Chobe ecosystem and its vegetation during the 150 or more turbulent years covered by this chapter. There have been others. The chapter discusses the vegetation dynamics that took place concurrently with the fall and rise of the elephant population following the ivory hunt in the end of the 20th century, and explains the relative importance of elephants, smaller herbivores and direct human impact through logging, burning and livestock grazing in causing these changes. The fall and rise of the Chobe elephant population during the last 150 or so years, has affected the vegetation on the relatively nutrient rich alluvium differently from that on the nutrient-deficient sand.
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| 5. |
- Skarpe, C., et al.
(author)
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Plant-Herbivore Interactions
- 2014
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In: Elephants and Savanna Woodland Ecosystems. - Chichester, UK : Wiley-Blackwell. - 9781118858615 - 9780470671764 ; , s. 189-206
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Book chapter (peer-reviewed)abstract
- To a casual observer, the importance of large herbivores for ecosystem structure and dynamics can seem more obvious in African savannas than in many other ecosystems because of their high abundance, diversity and species richness of ungulates. African savannas have also had a long uninterrupted history of mammalian herbivory, leading to the evolution of plant traits adapted to herbivory and to reciprocal traits in herbivores. In nutrient-poor savannas such as those on Kalahari sand in the Chobe National Park, Botswana, elephants, Loxodonta africana, are a main agent creating spatial and temporal variation in the vegetation and ecosystems. Within this framework, elephants and smaller herbivores interact with individual plants and plant populations, exploiting and modifying heterogeneity at many scales. Intermittent grazing in systems of migratory or highly mobile herbivores provides food plants with a recovery period, and could be one reason for the 'success' and abundance of many migratory herbivore species.
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| 6. |
- Wallgren, Märtha, et al.
(author)
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Influence of land use on the abundance of wildlife and livestock in the Kalahari, Botswana
- 2009
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In: Journal of Arid Environments. - : Elsevier BV. - 0140-1963 .- 1095-922X. ; 73:3, s. 314-321
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Journal article (peer-reviewed)abstract
- Human land use such as pastoralism may be a key determinant of wildlife populations. We studied the influence of land use on wildlife and livestock in south-western Kalahari, Botswana, during the wet and dry seasons. We included two types of livestock areas and two types of wildlife protection areas. Wild and domestic mammals >0.2 kg were sampled by distance technique. Small mammals <0.2 kg were trapped and a vegetation survey was performed. Livestock and some medium-sized wildlife species were most abundant in livestock areas, while large-sized wildlife species were mainly restricted to wildlife areas. Most red-listed species were confined to the national park. The influence of land use on abundances changed moderately between seasons. However, cattle moved into wildlife areas during the wet season. Differences in species richness and diversity were most pronounced during the dry season. The trapping frequency of small mammals was highest in the national park. Differences in vegetation structure included sparser field layer and higher cover of an invasive shrub in livestock areas. Our study shows the importance of protected areas for many wildlife species in the Kalahari. It also shows the value of a multi-species approach for investigating the effects of land use on wildlife communities.
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| 7. |
- Zhang, W, et al.
(author)
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Small-scale vegetation dynamics in semi-arid steppe in Inner Mongolia
- 1996
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In: JOURNAL OF ARID ENVIRONMENTS. - : ACADEMIC PRESS LTD. - 0140-1963. ; 34:4, s. 421-439
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Journal article (other academic/artistic)abstract
- Small-scale vegetation dynamics were followed for ecotones and in uniform stands in Artemisia-dominated steppe vegetation under grazing and when recovering from heavy grazing. Species composition was followed annually for 5 years in 1 m(2) and 0.25 m(2) p
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