Title:
Spatial characteristics of riparian woodlands in the distal Okavango Delta
Publication Year:
2001
Abstract:
The study area is located towards the southeastern or distal margin of the Okavango Delta. The present work was intended to provide some riparian zone characterisation of six distal distributaries using fieldwork and satellite imagery, with a view to determining whether differences in woody cover could be related to the present flow regimes. There are very few characteristics which uniquely single out, for instance, the perennially wet Boro system from the relatively dry Shashe river. However tree heights in the Boro are higher than those occurring in the Shashe. In contrast overall plant density is high in the Shashe and low in the Boro. It appears that two criteria, tree height and plant density, may be used to signify relative activity in terms of flow, although more work would be required to establish this differentiation throughout the delta. The second aim was to provide some indication as to whether downstream changes in riparian zone characteristics could reflect the history of flood pulse changes throughout the various distributaries. There is a propensity for plant density to increase downstream, for plant leaf area to decrease downstream and for shrub height to increase downstream. The overall conclusions here are that either there are insufficient data to reflect changes in flooding history in the six distributary systems or all of the systems are essentially similar in their flood pulse history with just minor variations occurring within the last decade. The high tree/shrub ratios in the Xudum, Matsibe and Shashe rivers may be indicative of long term drying trends. In contrast the Boro, Kunyere and Thamalakane have low tree/shrub ratios. The high incidence of shrubs in the Boro may relate to the relatively high annual groundwater table. However, in the case of the Kunyere and Thamalakane the high incidence of shrubs is just as likely to be related to human induced influences, for instance tree felling and livestock activities.
Publication Title:
Botswana Notes and Records
Volume:
33
Pages:
101-114
Item Type:
Journal Article
Language:
en

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