Mountains in East Africa: the missing Commonwealth dimension
Mountains play a vital ro˘le in the global ecosystem and economy. They are a source of most of the world's fresh water and many mountain regions possess key sites of biodiversity, while forested areas are both economically and ecologically important. While international agencies variously highlight mountain issues, there is virtually no direct involvement of Commonwealth-based activities, despite the fact that the Commonwealth contains some of the world's most significant mountain areas. In the wake of the 2002 International Year of the Mountains, the author draws on 15 years of studies of the East African Mountains to examine the successes and failures of government policies and international interventions.
Vegetation dynamics in central Africa since 18,000 yr BP: pollen records from the interlacustrine highlands of Burundi, Rwanda and western Uganda
A standardized analysis of palaeoecological data, in the form of six pollen sequences and forty‐ four radiocarbon ages, has permitted a region‐wide reconstruction of Late Quaternary vegetation dynamics for the interlacustrine highlands of central Africa.
Tools for Sediment Management in Rivers
Sediment management, including supply and continual redistribution of sediments for channel maintenance and channel forming, is critical for effective environmental water programs. Many tools have been developed to more effectively manage sediment in rivers for ecosystem maintenance and improvement. This chapter reviews some of these tools, including sediment mobilization theory, environmental water requirements for geomorphic maintenance, and complementary options. Sediment mobilization theory addresses entrainment, transport, and deposition of sediment particles. Environmental flows assessment approaches that support geomorphic processes include threshold-based approaches, field/laboratory methods, and holistic methods. Complementary options for sediment management include catchment-scale conceptual models and budgets for sediment, basin land management (e.g., reforestation, better agriculture practices, etc.), sediment management through dams, and sediment augmentation below dams. These complementary options often have cobenefits with other management objectives. The chapter emphasizes that sediment management is generally complex, such that continual research is needed, ranging from improved sediment mobilization models to large-scale river experiments.