How do plant demographic and ecological traits combined with social dynamics and human traits affect woody plant selection for medicinal uses in Benin (West Africa)?

BACKGROUND: Several hypotheses have been used in ethnobotany to explain the plant's selection criteria by people for their daily needs. Thus, it is important to assess synergy and complementarity among them, especially, those concerning the plant use value, social dynamics and human traits. The study aims to (i) highlight people's socio-economic factors, and plant ecological traits that affect the plant use-availability dynamic (PUD); and (ii) assess the available species diversity effect on ethno-medicinal knowledge diversity in Benin. METHODS: Ethnobotanical interviews were carried out to quantify the importance of local species in different ecological zones of Benin with 590 traditional medicine actors. Vegetation surveys were done to assess species availability within 337 plots of 50 m x 40 m or 60 m x 30 m, depending on the climatic zone, for a total of 61.6 ha, established in 15 forests distributed within the 10 phytodistricts of Benin. The plant use availability hypothesis was quantified as a dynamic link between species use value and availability (PUD). A general and mixed linear models were used to assess the significance of each factor's effect on PUD. Pearson correlation test was applied on Shannon diversity index considering inventoried species in the field and those which were cited by people, for the available species diversity effect on ethno-medicinal knowledge diversity assessment. RESULTS: A hundred and twenty woody medicinal plants, mostly trees (68.33%), were sampled. Growth form and its interaction with phytodistrict have a significant effect (p: 0.005) on PUD. The less available trees were the most used in the phytodistricts 3, 4, 8 and 10. PUD varies significantly according to social factors (p: 0.007). Ethnicity, age and main activity were the most quoted social factors which influenced the PUD. Ethnicity and age have various effects considering the phytodistricts. Moreover, the influence of age changes following the main activity. Plant selection did not solely link to the surrounding diversity (r: - 0.293; p: 0.403). Within some phytodistricts, especially those of 3, 4, 8 and 10, the less available tree species were the most requested. CONCLUSION: It is urgent to reforest vegetation patches in some phytodistricts (3, 4, 8 and 10) of Benin with widely requested and no available species to avoid the extinction of their wild populations. This concerns Cassia sieberiana DC., Anonychium africanum (Guill. & Perr.) C. E.Hughes & G. P. Lewis, Pterocarpus erinaceus Poir., Cola millenii K. Schum., Azadirachta indica A. Juss., Khaya senegalensis (Desr.) A. Juss., Pseudocedrela kotschyi (Schweinf.) Harms, Treculia africana Decne. ex Trécul, Uapaca heudelotii Baill., Vitellaria paradoxa C. F. Gaertn., Kigelia africana (Lam.) Benth. and Newbouldia laevis (P. Beauv.) Seem. ex Bureau.

Factors shaping local people's perception of ecosystem services in the Atacora Chain of Mountains, a biodiversity hotspot in northern Benin.

BACKGROUND: Atacora Chain of Mountains (ACM) is the Benin part of a range of mountains lying from Benin to Ghana through Togo. It provides goods and services to people and is dominated by rural communities with heavy reliance on natural resources. The ACM may be threatened by the increasing resource needs and the possible shift in people's livelihood priorities brought about by challenges and opportunities ushered in by modernization. This study sought to understand local people's perception of the services derived from the ACM and the socio-demographic factors (age, gender, and level of urbanization of the place people live in) accounting for these perceptions. METHODS: Face to face interviews with 12 focus groups in 3 municipalities were carried out to obtain a list of ecosystem services cited by the participants. At the individual level, 144 people (men, women, young, adult, and old people from either rural or urbanized areas) equally distributed in the 3 municipalities were asked whether they acknowledge each of the services cited by the focus groups. Logistic regressions were then used with generalized linear models (GLM) function in R to analyze the relationships between the probability of acknowledgement of a service by the respondents and their socio-demographic characteristics. RESULTS: Local people perceived the ACM as a provider of provisioning, supporting, and cultural services but cited more provisioning services than the others. The factors considered in this study (gender, location, and age) were all predictors of ecosystem services perception in the ACM. Location influenced people's perception of provisioning and supporting services such that respondents from rural municipalities were more likely to perceive provisioning and supporting services. This is because people in rural areas have a heavier reliance on natural resources. Gender was associated with respondents' perception of supporting, provisioning, and cultural services. Women were more likely to perceive provisioning services and less likely supporting and cultural services. People in each category of gender have a perception of ES linked to their livelihood activities. Young people were less likely to perceive supporting services than adults and old people due to their less involvement in farming activities. CONCLUSIONS: This study showed that gender, location, and age predict local people's perception of ecosystem services in the ACM and livelihood orientation is determinant. The omission of regulation and many of the supporting services questions the future of this mountain chain if its exploitation continues without any awareness and conservation measures.

Functional traits partially mediate the effects of chronic anthropogenic disturbance on the growth of a tropical tree.

Understanding how trees mediate the effects of chronic anthropogenic disturbance is fundamental to developing forest sustainable management strategies. The role that intraspecific functional diversity plays in such process is poorly understood. Several tree species are repeatedly defoliated at large scale by cattle breeders in Africa to feed livestock. In addition, these tree species are also debarked for medicinal purposes. These human-induced disturbances lead to biomass loss and subsequent decline in the tree growth. The main objective of this work is to investigate how functional traits mediate tree response to chronic anthropogenic disturbance. We used a unique data set of functional traits and growth rate of 503 individual tree of Afzelia africana. We collected data on leaf mass per area (LMA), wood density (WD) and growth rate, and recorded history of human disturbances (debarking, pruning) on individual tree from 12 populations of A. africana distributed in two ecological zones in Benin (West Africa). We tested the effect of disturbances on absolute growth rate across ontogenetic stages, assessed the role of intraspecific trait variability on growth and tested the role of tree functional strategy on the tree growth response to debarking and pruning. We found that debarking did not affect stem growth, suggesting a fast compensatory regrowth of bark wounded. Moreover, tree response to debarking was independent of the functional strategy. By contrast, we found that pruning reduced tree absolute growth; however, trees with low WD were more strongly affected by pruning than trees with high WD. Our results emphasize the importance for plant functioning of the interplay between the availability of leaves for resource acquisition and a resilience strategy by mobilizing stored resources in stem wood to be reinvested for growth under severe disturbances.

Response of a tropical tree to non-timber forest products harvest and reduction in habitat size.

Non-timber forest products (NTFPs) are widely harvested by local people for their livelihood. Harvest often takes place in human disturbed ecosystems. However, our understanding of NTFPs harvesting impacts in fragmented habitats is limited. We assessed the impacts of fruit harvest, and reduction in habitat size on the population structures of Pentadesma butyracea Sabine (Clusiaceae) across two contrasting ecological regions (dry vs. moist) in Benin. In each region, we selected three populations for each of the three fruit harvesting intensities (low, medium and high). Harvesting intensities were estimated as the proportion of fruits harvested per population. Pentadesma butyracea is found in gallery forests along rivers and streams. We used the width of gallery forests as a measure of habitat size. We found negative effects of fruit harvest on seedling and adult density but no significant effect on population size class distribution in both ecological regions. The lack of significant effect of fruit harvest on population structure may be explained by the ability of P. butyracea to compensate for the negative effect of fruit harvesting by increasing clonal reproduction. Our results suggest that using tree density and population structure to assess the ecological impacts of harvesting clonal plants should be done with caution.