Assessing the impact of bark and foliage harvest on Khaya senegalensis (Meliaceae) in Benin, West Africa

Thousands of plant species worldwide are harvested for multiple non-timber forest products (NTFP), by multiple user groups, and across ecologically variable regions. However, there is little information on patterns of NTFP harvest and their ecological impacts on populations in these complex socio-ecological contexts. This lack of information limits our understanding of human-plant interactions across both historic and contemporary time scales, and of their implications for plant conservation. This dissertation explores these issues by using an ethnoecological approach to assess local patterns of bark and foliage harvest from Khaya senegalensis (Meliaceae), identify local knowledge and perceptions of harvest impacts, and test if and how variation in harvest (high versus low) and in ecological conditions (dry versus moist) alter population structure, reproductive output, ecophysiology and population dynamics in Benin, West Africa. Across the two ecological regions studied, bark harvest rate was low but foliage harvest rate was high. Although foliage harvest increased leaf nitrogen content in the dry region, it was constrained by higher cost of leaf construction. Harvest reduced fruit production in the drier region and seed weight in the moist region. Matrix population models suggested that harvested populations will decline over the long term in both regions, and that populations in the drier region will decline faster. This declining trend was consistent with perceptions of Fulani herders, who harvest the species as a fodder-medicine for their cattle. Fulani ecological knowledge of the impacts of harvest was detailed, specific to location, and was consistent with ecological findings. However, despite local knowledge of appropriate harvest limits, local harvesters are not expected to reduce the current harvesting rates given the multi-contextual harvest of K. senegalensis. Suggested conservation strategies include increasing the availability of K. senegalensis fodder by promoting Fulani-owned plantations, reducing pressure of illegal logging by encouraging private/government timber plantations, and planting K. senegalensis trees along migration corridors. This dissertation illustrates how the impacts of NTFP harvest may be more severe in populations subject to more arid conditions, and how detailed local ecological knowledge is only one of various factors necessary for community level sustainable management.