Structural diversity and tree density drives variation in the biodiversity-ecosystem function relationship of woodlands and savannas.

Positive biodiversity-ecosystem function relationships (BEFRs) have been widely documented, but it is unclear if BEFRs should be expected in disturbance-driven systems. Disturbance may limit competition and niche differentiation, which are frequently posited to underlie BEFRs. We provide the first exploration of the relationship between tree species diversity and biomass, one measure of ecosystem function, across southern African woodlands and savannas, an ecological system rife with disturbance from fire, herbivores and humans. We used > 1000 vegetation plots distributed across 10 southern African countries and structural equation modelling to determine the relationship between tree species diversity and above-ground woody biomass, accounting for interacting effects of resource availability, disturbance by fire, tree stem density and vegetation type. We found positive effects of tree species diversity on above-ground biomass, operating via increased structural diversity. The observed BEFR was highly dependent on organismal density, with a minimum threshold of c. 180 mature stems ha-1 . We found that water availability mainly affects biomass indirectly, via increasing species diversity. The study underlines the close association between tree diversity, ecosystem structure, environment and function in highly disturbed savannas and woodlands. We suggest that tree diversity is an under-appreciated determinant of wooded ecosystem structure and function.

Ethnobotany in Angola: The contribution of late 19th century christian missionaries to the knowledge of medicinal wild plants.

ETHNOPHARMACOLOGICAL RELEVANCE: Angola has an extraordinary plant diversity and a great ethnobotanical potential. However, there is a general lack of information about the first botanical explorations in the country and their contribution to the knowledge of the medicinal flora. AIM OF THE STUDY: The main aim of this study was to unveil the ethnobotanical legacy of José Maria Antunes and Eugène Dekindt, priests of the first Catholic mission in Huíla (Angola) and shed light on their contribution to the knowledge of medicinal wild plants of the country, including information on the uses, plant parts used, and preparation methods documented in the late 19th century. The findings are discussed considering recent ethnobotanical studies to offer a more comprehensive understanding of the historical and traditional uses of plants in Angola over the last two centuries. MATERIALS AND METHODS: Based on the information available in manuscripts and on the study of botanical collections preserved in herbaria of Portugal and Angola, we extracted relevant information about the species used in traditional medicine by the rural population of Huíla, the health conditions treated, and the mode of preparation and application. RESULTS: Our results revealed that Antunes and Dekindt conducted the first ethnobotanical study in Huíla, and documented a large number of medicinal wild plants. From these, we report 191 medicinal species, including 25 endemic and four introduced species, belonging to 56 plant families and 146 genera. Fabaceae family presents the highest richness of medicinal plants (39 taxa), followed by Rubiaceae (13), Asteraceae (10), and Apocynaceae (9). The illnesses reported were classified into 15 different categories, with the highest number of species (49) corresponding to unspecific conditions, such as general pains, chills, and fever. Thirty-seven species were reported for respiratory diseases, 31 for musculoskeletal problems, and 30 for digestive issues. Leaves were the most used plant part for medicinal purposes (84 species). Infusion was the most frequently described preparation method (40 species), followed by maceration (24 species), and powdering (36 species). CONCLUSIONS: The legacy of Antunes and Dekindt's work improves our understanding of Angola's botanical richness and traditional uses of plant resources. Our findings highlight the presence of unique medicinal resources in Angola, especially among endemic species, which hold the potential to improve the quality of life of rural communities. Moreover, our research underscores the lack of knowledge of medicinal species, emphasizing the risk of losing valuable historical information.