| The Tana River National Primate Reserve (TRNPR) was established in 1975 to preserve the endemic and endangered red colobus (Colobus badius rufomitratus) and crested mangabey (Cercocebus galeritus galeritus) and the riverine forest ecosystem. Between 1975 and 1985 the population of these primates declined to critically low levels. Through a study of current forest ecology I have addressed three primary research questions: (1) do vegetation-based factors explain the recent decline; (2) what are the current status and future status of the Reserve's forest as primate habitat; and (3) which management alternatives would best ensure future preservation?; The research has been directed at the characterization of suitable habitat for the endangered primates, the trends toward the development or loss of suitable habitat, the disturbance factors influencing the current distribution of contrasting habitat, and habitat restoration. Data were collected on forest composition, structure, regeneration, and disturbance within 12 forest areas. Analyses focus on the relationships among these attributes and primate abundance and/or utilization patterns, a comparison among the study areas, and overall characteristics of the riverine forest patches.; The riverine forest mosaic has served as an isolated refuge for plant and animal species adapted to a moist climatic regime. The plant diversity of the ecosystem is demonstrated by the assortment of species from the major floristic regions in Africa and the migration patterns represented by their disjunct occurrences. Downstream, the pattern of river meanders, erosion, and deposition results in the highest diversity of landforms and forest types in the TRNPR vicinity, but regional diversity of the ecosystem is not adequately protected without the inclusion of forests in the Bura and Wema/Hewani regions.; The colobus and mangabey are interior-forest primates, demonstrating a preference for high-stature, closed-canopy forests with high area-to-perimeter ratios and low intraforest disturbance. Forest loss, fragmentation, and consequent reduction in the area-to-perimeter ratio of the remaining forests measured from 1960 and 1975 photos provide a partial explanation for the decline in primate populations. High-quality habitat corresponds to nearly monodominant Pachystela msolo forests or mixed forests with Sorindeia madagascariensis and Diospyros mesphiliformis. Ficus sycomorus, a primary food resource, establishes as a pioneer, but persists in association with these forests. Forest regeneration is characterized by an absence of self-replacement, intraforest heterogeneity attributable to gaps, changing site conditions, and unstable forest communities. Forest restoration would serve to alleviate local disturbances attributed to floodplain dynamics and forest clearing and encourage the establishment of suitable primate habitat. The conservation goal should be to couple species preservation with the preservation of natural ecosystem integrity within this dynamic landscape along the Tana River. |
