Mine versus Wild : a plant conservation checklist of the rich Iron-Ore Ngovayang Massif Area (South Cameroon)

International audienceBackground and aims – The rapid expansion of human activities in South Cameroon, particularly mining in mountainous areas, threatens this region’s exceptional biodiversity. To comprehend the effects of land-use change on plant diversity and identify conservation priorities, we aim at providing a first comprehensive plant checklist of the Ngovayang Massif, focusing on the two richest plant families, Orchidaceae and Rubiaceae.Location – The Ngovayang Massif Area (NMA) is located in the South Region of Cameroon. It is covered by lowland and submontane rainforest (100 to 1110 m elevation).Methods – We compiled a dataset of 6116 georeferenced herbarium specimens, of which 2787 belong to Rubiaceae and Orchidaceae. We used rarefaction methods to explore sampling and diversity patterns, and investigated the altitudinal distribution of rare and/or threatened taxa.Key results – The NMA, which houses about 1500 vascular plant taxa, is the richest documented area for Rubiaceae in Atlantic Central Africa (ACA) and the fifth for Orchidaceae, with respectively 281 and 111 taxa. Among these taxa, 178 (45%) are endemic to ACA and 67 (17%) are considered globally threatened according to IUCN categories and criteria. We show that higher elevation areas (> 750 m), which are also the main areas targeted for mining, are the richest in endangered and/or rare species. Three new records for Cameroon are reported here.Conclusion – The NMA represents an Important Plant Area of Cameroon as confirmed by its exceptional plant diversity (> 20% of the total Flora of Cameroon), by the concentration of many threatened and/or restricted range species (10 taxa are strict endemics of the massif) as well as by the threat on rare habitats (i.e. the submontane vegetation above ~750 m elevation). A management plan involving in situ and ex situ conservation actions is urgently needed to reduce the potential threats of future mining activities

Additive influences of soil and climate gradients drive tree community composition of Central African rainforests

International audienceAim: Examining tree species-environment association can offer insight into the drivers of vegetation patterns and key information of practical relevance to forest management. Here, we aim to quantify the contribution of climate and soil gradients to variation in Central African tree species composition (abundance and occurrence). Location: Tropical rainforests of southern and eastern Cameroon. Methods: We established 82 1-ha permanent plots across seven localities and censused all trees ≥ 10 cm in diameter, representing a total of 37,733 trees and 455 species. In 60 of those plots, we measured ten soil variables describing texture and nutrients levels and extracted ten bioclimatic variables from global-gridded climate databases. We synthesized the main environmental gradients by conducting principal component analyses on climate and soil data respectively. We performed unconstrained and constrained non-symmetric correspondence analyses to account for the individual and joint contributions of climate and soil on species abundance and occurrence. Results: Climate and soil contributed similarly to variances of species abundance and occurrence (12–15 % variance for climate vs. 11–12 % variance for soil). Climate influence mostly concerns some abundant species, while some of the less abundant species were mainly driven by soil. Fractions of species variances accounted for by climate and soil show strong correlation when assessed from species occurrence and abundance data. Conclusion: Variation in occurrence and abundance of tropical forest trees can be partly shaped by both climate and soil gradients in Cameroon, which emphasizes the importance to jointly consider soil and climate in species distribution modeling. Less abundant species may express environmental influence differently than abundant species and convey complementary information about community assemblage. Though showing congruent patterns here, species abundance and occurrence reflect different interacting community processes and both should be examined to better understand vegetation patterns

P38. More than twenty years of orchid ex situ conservation in Africa and Madagascar

International audienceOrchid conservation represents a significant challenge inTropical Africa and Madagascar, areas in which habitats are facing increasing pressure from agriculture, mining and logging activities. In these regions, a large part of the epiphyte flora is composed of orchids, most of which, when lacking flowers when encountered in the field, are impossible to identify. However, accurate identification is essential for developing conservation strategies since about 69% of tropical Africanand Malagasy orchids are potentially threatened. To overcome this identification problem, a shadehouse cultivation system was developed in São Tomé in 1997 and has now been extended across Continental Africa and Madagascar, providing a powerful tool for conducting thorough orchid inventories since most epiphytes can easily be brought into cultivation and grown to produce fertile, identifiable material. The network currently counts 12 shadehouses in sixcountries and, to date, 32,013 living orchids collected in the field have been grown, representing about 500 species, from which >23,764 herbarium specimens have been collected, most associated with silicagel-preserved material and photos. This material has been usedto describe 41 previously unknown species and to assess the conservation status of hundreds of species in three key areas (West Africa, Central Africa and Madagascar), while also leading to the publication of 44 articles in taxonomy, phylogeny, floristics and for the general public. Initially designed to facilitate orchid inventory and identification, the shadehouses now contribute to orchid conservation by protecting plants in safe, controlled conditions, producing material for seeds banking. They also offer valuable training opportunities for young botanists, thereby contributing to in-country capacity building. Key factors that explain the success of this shadehouse network and its long-term survival are the support provided by reliable local partners, the involvement of young botanists and students, and the development of new techniques to grow thousands of living orchids successfully and cost-effectivel