Advances in Coastal Ecology: people, processes and ecosystems in Kenya

Assessment of rehabilitation success of post-mining landscapes is a recent field of ecology necessitated by the growing global awareness of negative impacts of mining and need for legislative compliance. The Bamburi Cement Company has made rehabilitation a natural part of the business process and for the last 35 years has been rehabilitating exhausted quarries in Mombasa, Kenya. It is generally acknowledged that the project has been successful and Bamburi's man-made forested ecosystems are celebrated as showcases of rehabilitation. The goals of quarry rehabilitation by Bamburi are to re-create self-sustaining tropical forests typical of the Kenya coast but how can we measure how well we are doing? We conducted surveys comparing vegetation characteristics after 35 years in three different planting treatments with a natural coastal forest which we proposed could be the end point or reference. After 35 years of rehabilitation, the forests were tall in stature with high rates of nutrient turnover but were structurally simple compared to the native coastal forest. Biodiversity was lower than in the natural forest though enrichment planting can correct this. Where introductions have been ongoing, species richness was 61% of the native forest. Low rates of natural introductions and establishment indicated that continued active enrichment planting will be required for some time, as well as the active removal of aggressive invasive species such as the neem (Azadirachta indica). Soil formation processes were active and the most important arthropod responsible for nutrient turnover was the red legged millipede (Epibolus pulchripes) which was estimated to consume between 22 and 44% of the annual leaf fall. Published