The coastal forests of East Africa are a biodiversity hotspot of global importance. They contain some of the highest densities of endemic plants of anywhere in the world. Over 550 species of plants, and a total of 776 species across all taxa, are known only from the scattered patches of forest along Africa's eastern edge. Endemic species include Kretschmer’s Longbill Macrosphenus kretschmeri, which is known to occur in the forests of Kilwa. Rates of endemism are particularly high for invertebrate groups such as millipedes (maybe > 80%) and molluscs (68%). The forests of southern Tanzania and northern Mozambique are amongst the least studied of all, and more endemics will probably be discovered.
The strict definition of coastal forest applies only to areas where the tree canopies are touching, creating a more closed environment than the open miombo woodlands. However strict adherence to such definitions is not always appropriate. In reality there is often a continuum between closed and open areas. In addition over two-thirds of the estimated original extent has been cleared, and much of the remaining 'true' forest is found only in scattered and isolated fragments. Many of the intermediate areas, given time, would likely return to their natural forested state, and even when degraded may harbour some endemics. Mpingo is a hypothetical pioneer species, and so may have an important role to play in this process.
So far over 200 coastal forest fragments have been identified in Kenya and Tanzania alone. 60% of these are under 500ha in size, and many smaller ones are waiting to be found and investigated. Most of these sites are unprotected and surrounded by poor, resource-hungry rural communities, while existing reserves suffer from high levels of encroachment. Population in the region as a whole is increasing rapidly so without action further fragmentation and degradation is inevitable.