| 1. |
- Aarrestad, P. A., et al.
(författare)
-
Influence of soil, tree cover and large herbivores on field layer vegetation along a savanna landscape gradient in northern Botswana
- 2011
-
Ingår i: Journal of Arid Environments. - : Elsevier BV. - 0140-1963 .- 1095-922X. ; 75:3, s. 290-297
-
Tidskriftsartikel (refereegranskat)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.
|
|
| 2. |
- Aarrestad, P. A., et al.
(författare)
-
Vegetation : Between Soils and Herbivores
- 2014
-
Ingår i: Elephants and Savanna Woodland Ecosystems. - Chichester, UK : Wiley-Blackwell. - 9781118858615 - 9780470671764 ; , s. 61-88
-
Bokkapitel (refereegranskat)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.
|
|
| 3. |
- Skarpe, C., et al.
(författare)
-
Historical Changes of Vegetation in the Chobe Area
- 2014
-
Ingår i: Elephants and Savanna Woodland Ecosystems. - Chichester, UK : Wiley-Blackwell. - 9781118858615 - 9780470671764 ; , s. 43-60
-
Bokkapitel (refereegranskat)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.
|
|
