Connecting plant evolutionary history and human well-being at Mt. Kilimanjaro, Tanzania

Evolution is the source of all living organisms and hence the foundation for the ecosystem services that are directly supported by biodiversity. However, explicit connections between evolutionary history and human well-being are barely explored. Here, we focus on ethnobotanical data from Mt. Kilimanjaro (Tanzania) to identify significant associations between plant evolutionary lineages and six previously recognized usage guilds in the mountain (i.e. fodder, building material, fuelwood, food, ornamental/shading and traditional medicine), and further characterize the degree of phylogenetic overlap between the guilds using beta diversity metrics. In addition, we also explore how phylogenetic diversity of usage guilds varied along elevation and between natural and anthropized habitats. Our results suggest that the inhabitants of Mt. Kilimanjaro rely on multiple and deep lineages that specifically provide a certain type of service, supporting the notion that an increased number of lineages captures more current biodiversity benefits. However, we also found a few lineages that provided multiple benefits, indicating that particular efforts should be pursued in preserving individual multi-functional lineages of the phylogeny. Elevation was the most important factor explaining phylogenetic diversity of useful plants, whereas the effect of anthropogenic disturbance was comparatively weak. However, after controlling for the effect of elevation, a moderate negative effect of human disturbance was revealed, particularly for medicinal plants. Phylogenetic diversity of most guilds showed hump-shaped curves with elevation, revealing a major reservoir of useful plant lineages in the highly threatened montane forests of Mt. Kilimanjaro.