| Abstract: | Riparian forests in the Sahel zone of Africa are of considerable importance for human resource use and for their ecological and conservation value. Typical riparian forest tree species are dependent on river flows and a shallow aquifer, and the community and population structure of riparian forests is related to spatial and temporal patterns of flooding at a site. Therefore, changes in hydrology caused by dams cause changes in floodplain vegetation. This paper explores the spatio-temporal complexity of these changes through an analysis of regeneration in a Nigerian floodplain affected by dams built in the early 1970s. The study shows that under certain conditions, and given sufficient time, riparian forests may be changing to forest types more characteristic of unflooded, upland areas. The results of the study have implications for the way in which the sustainability of developments downstream of large dams are analysed, suggesting that assessment of impacts must take place within temporal parameters relevant to ecological processes and at spatial scales that encompass spatial variation in floodplain ecosystems. |
