Effects of bark harvest and other human activity on populations of the African cherry (Prunus africana) on Mount Oku, Cameroon

Bark extracts from the African cherry, Prunus africana (Rosaceae), are a popular treatment for enlarged prostates. Harvests of the bark began in Cameroon in the 1970s. Because of concerns regarding the sustainability of the trade, the species is included on the IUCN Red List and in CITES Appendix II. This study followed five P. africana populations in the Kilum-Ijim Forest Preserve on Mount Oku, Cameroon, examining growth, mortality and reproductive parameters, as well as response to harvest and other human activities. During the first part of the study (1998-1999), the forest had limited human activity; by the second part (2007-2008), more activity was apparent, including wildfires, grazing and a forest-wide bark harvest in 2005/2006. Over the study period, population structure differed from a typical]shaped frequency curve for long-lived species, which may reflect past harvesting. After the 2005/2006 harvest, the population structure had shifted slightly toward the smaller size classes. In addition, the number of surviving trees was reduced in all size classes. About half of the reproductive trees died during the study. Size class was not a significant predictor of death, but the location of the harvest (plot) was. All trees affected by wildfires died, suggesting that the species is not adapted to fire. Trees that were harvested without disrupting the vascular cambium survived better and had minimal loss of crown. Thus, the fate of the trees in a given plot may lie in the care taken by an individual harvester. Average growth (0.34 cm per year) was not significantly different among the size classes. Crown die-back significantly reduced fruit production, obscuring the asynchronous alternating fruiting pattern. Seedling numbers followed a similar alternating pattern, but survival was negligible due to grazing. The combined factors of mortalities of a large percentage of reproductive trees (especially the largest ones), highly reduced fruit production and poor seedling survival offer a bleak prognosis for future regeneration and long-term persistence of the species in this forest. Only after decades of harvest are existing standing crop inventories and scientifically based annual quotas now being determined. It is known that the trees are easily domesticated. Efforts have been intensified to train villagers and community forest managers in vegetative propagation techniques and nursery practices, offering some hope that the species can be successfully managed to provide for sustainable harvests and dependable rural livelihoods. (C) 2009 Elsevier B.V. All rights reserved.