Species’ functional traits set the blueprint for pair-wise interactions in ecological networks. Yet, it is unknown to what extent the functional diversity of plant and animal communities controls network assembly along environmental gradients in real-world ecosystems. Here we address this question with a unique dataset of mutualistic bird–fruit, bird–flower and insect–flower interaction networks and associated functional traits of 200 plant and 282 animal species sampled along broad climate and land-use gradients on Mt. Kilimanjaro. We show that plant functional diversity is mainly limited by precipitation, while animal functional diversity is primarily limited by temperature. Furthermore, shifts in plant and animal functional diversity along the elevational gradient control the niche breadth and partitioning of the respective other trophic level. These findings reveal that climatic constraints on the functional diversity of either plants or animals determine the relative importance of bottom-up and top-down control in plant–animal interaction networks.

We used the broad elevational gradient of Kilimanjaro ranging from warm tropical lowland to cold Afroalpine temperature regimes and the occurrence of natural, nearly untouched as well as of anthropogenic and heavily disturbed habitats to study how elevation and disturbance by humans affect the proportion of useful plant species in different habitat types. Of the 962 vascular plant species recorded in our 60 study plots, 563 species turned out to be listed as useful in the literature. We classified these species into six usage categories. With linear models we tested for relationships between the proportion of useful species per plot and elevation for natural habitats, and with analysis of variance we compared the proportion of useful species between plots in disturbed and natural habitats at similar elevation. The proportion of useful species for all usage categories increased from 860 to 2500 m asl and decreased with higher elevation. We also found an overall positive correlation between the number of useful plants and the species richness of our plots. Human-influenced habitats had higher proportions of useful species for all usage categories, except for construction and fuel wood usage which were higher in natural savanna and lower montane forest than in used habitats at these elevations. Given the high proportions of useful species, we conclude that preserving the biodiversity of Kilimanjaro ecosystems is indispensable for maintaining the diversity of useful plants species for the local people who rely on it for food, sustainable access to medicinal, fuel, construction and forage material.

Tropical mountains and especially their forests are hot spots of biodiversity threatened by human population pressure and climate change. The diversity of lichens in tropical Africa is especially poorly known. Here we use the mtSSU and nuITS molecular markers together with morphology and ecology to assess Leptogium (Peltigerales, Ascomycota) diversity in the tropical mountains of Taita Hills and Mt. Kasigau in Kenya and Mt. Kilimanjaro in Tanzania. The sampled habitats cover a wide range of ecosystems from savanna to alpine heath vegetation and from relatively natural forests to agricultural environments and plantation forests. We demonstrate that Leptogium diversity in Africa is much higher than previously known and provide preliminary data on over 70 putative species, including nine established species previously known from the area and over 60 phylogenetically, morphologically, and/or ecologically defined Operational Taxonomic Units (OTUs). Many traditional species concepts are shown to represent morphotypes comprised of several taxa. Many of the species were only found from specific ecosystems and/or restricted habitats and are thus threatened by ongoing habitat fragmentation and degradation of the natural environment. Our results emphasize the importance of molecular markers in species inventories of highly diverse organism groups and geographical areas.

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.