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

Vincent Droissart,Hermann Taedoumg,Steven Dessein,Murielle Simo-Droissart,Olivier Lachenaud,Gilles Dauby,Charlemagne Nguembou K,Gyslène Kamdem,Tariq Stévart,Bonaventure Sonké

doi:10.5091/plecevo.2019.1547

Abstract

Background 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.

Highlights

The flora of Cameroon is one of the richest of the African continent, with about 7000 species recorded to date (Onana 2011, Sosef et al 2017)
This sampling effort represents more than 5% of the total number of specimens collected in Cameroon, while the surface of the Ngovayang Massif Area (NMA) only represents 0.1% of the country
For the two families here studied in detail (Rubiaceae and Orchidaceae), 17.1% of the species occurring in the NMA are considered threatened according to IUCN red list categories and criteria (IUCN 2012)

Summary

Introduction

The flora of Cameroon is one of the richest of the African continent, with about 7000 species recorded to date (Onana 2011, Sosef et al 2017). Cameroon has been relatively well explored for plants compared to most other tropical African countries but prospecting efforts within the country have been very unequal (Onana 2011, Sosef et al 2017), and the heterogeneous information on plant distribution limits effective conservation actions. The NMA represents a relatively well botanically sampled place in the South Region of Cameroon: more than 6000 herbarium specimens have been collected in this area (compared to the ~90 000 specimens collected in Cameroon, Sosef et al 2017). This sampling effort represents more than 5% of the total number of specimens collected in Cameroon, while the surface of the NMA only represents 0.1% of the country. The only estimation for total number of plant species occurring in the NMA, i.e. 450 vascular plant species, was given by Gonmadje et al (2011), without indication of voucher specimens or sources used to generate this statistic

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Discussion

Conclusion