Original Research
Classification and mapping of the composition and structure of dry woodland and savanna in the eastern Okavango Delta
Michelle J. Tedder, Kevin P. Kirkman, Craig D. Morris, Winston S.W. Trollope, Mpaphi C. Bonyongo
About the author(s)
Michelle J. Tedder, School of Life Sciences, University of KwaZulu-Natal, South Africa
Kevin P. Kirkman, School of Life Sciences, University of KwaZulu-Natal, South Africa
Craig D. Morris, School of Life Sciences, University of KwaZulu-Natal, South Africa
Winston S.W. Trollope, Working on Fire International, Nelspruit, South Africa
Mpaphi C. Bonyongo, Okavango Research Institute, University of Botswana, Botswana
Abstract
The dry woodland and savanna regions of the Okavango Delta form a transition zone between the Okavango Swamps and the Kalahari Desert and have been largely overlooked in terms of vegetation classification and mapping. This study focused on the species composition and height structure of this vegetation, with the aim of identifying vegetation classes and providing a vegetation map accompanied by quantitative data. Two hundred and fifty-six plots (50 m × 50 m) were sampled and species cover abundance, total cover and structural composition were recorded. The plots were classified using agglomerative, hierarchical cluster analysis using group means and Bray-Curtis similarity and groups described using indicator species analysis. In total, 23 woody species and 28 grass species were recorded.
Acacia erioloba and
Colophospermum mopane were the most common woody species, whilst
Urochloa mossambicensis,
Panicum maximum,
Dactyloctenium gigantiumand
Eragrostis lehmanniana were the most widespread grasses. Eleven vegetation types were identified, with the most widespread being Short mixed mopane woodland, Tall mopane woodland and Tall mixed mopane woodland, covering 288.73 km
2 (28%), 209.14 km
2 (20%) and 173.30 km
2 (17%) of the area, respectively. Despite their extensive area, these three vegetation types were the least species-rich, whilst Palm thornveld, Short mixed broadleaf woodland and Open mixed
Acacia woodland were the most taxonomically variable. By contrast, Closed mixed
Acacia woodland and Closed
Acacia–
Combretum woodland had the most limited distribution, accounting for less than 1% of the mapped area each.
Conservation implications: The dry woodland and savanna vegetation of the Okavango Delta comprises a much wider suite of plant communities than the Acacia-dominated and Mopane-dominated classifications often used. This classification provided a more detailed understanding of this vegetation and essential background information for monitoring, management and research.
Keywords
Monitoring; Management; Botswana; Vegetation; Dryland
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Geocarto International vol: 33 issue: 5 first page: 489 year: 2018
doi: 10.1080/10106049.2016.1265598