PhD defense of GTI alumnus, Héritier Milenge Kamalebo

Release date	24/04/2019
Geographical coverage	DR Congo, Tshopo
Keywords	mycology, macrofungi, Macrofungal diversity, useful fungi, rainforests

The defense took place at Université de Kisangani, DR Congo.

The thesis was untertaken under the supervision of:

• Prof. Hippolyte NSHIMBA SEYA WA MALALE (University of Kisangani)
• Prof. Céphas MASUMBUKO NDABAGA (Official University of Bukavu)
• Dr André DE KESEL (Meise Botanic Garden, Belgium).

Abstract

Fungi constitute one of the most rich and diverse groups of organisms worldwide. Wild mushrooms provide diverse substances and services, especially food and income for numerous local communities. Diversity of fungi is however affected by host plant diversity and soil heterogeneity. Scientists have also reported that people lose part of their knowledge about mushrooms across generation. Documenting the traditional uses and cultural significance of wild fungi allows transferring knowledge across generation and cultures, and to better understanding the way in which fungi should be promoted. Hence, this study aims: i) to give an overview of wild edible fungi from the Yangambi Biosphere reserve and Yoko reserve rainforests of the province of Tshopo, ii) to assess the species richness and functional diversity of macrofungi within different forest stands, iii) to assess the influence of host plants and edaphic factors on the diversity and distribution of ectomycorrhizal fungal fruiting bodies and, iv) to provide original ethnomycological data from the communities living around the Man-and-Biosphere Reserve of Yangambi and the Yoko Forest Reserve.

To achieve this, fungal sampling was performed in plots placed within mixed and ectomycorrhizal monodominant forests. Composite soil samples were taken within ectomycorrhizal dominated forests at 0 to 30 cm depth. In each plot, the above ground encountered fungi fruiting bodies of Basidiomycetes and Ascomycetes were surveyed and harvested. Species richness was calculated as the number of fungal species collected from each type of forest while α (alpha) fungal diversity was determined using the Shannon (H) index. Ethnomycological surveys were made within local communities near the Biosphere reserve of Yangambi and the Yoko forest reserve. The interviews involved 160 informants from six different ethnic communities (Bakumu, Turumbu, Topoke, Lokele, Ngelema and Ngando). Specific reported use (RU), the relative importance (RI) and the cultural significance (CS) of wild edible fungi were calculated using quantitative data from enquiries.

The Gilbertiodendron dewevrei dominated forest was the most species-rich forest stand (p-value<0.001). Of the five reported functional/trophic groups (saprotrophic fungi, ectomycorrhizal fungi, insect parasitic fungi, plant parasitic fungi and termites’ symbiotic fungi), the saprotrophic fungi were the most abundant (210 species of a total of 341 taxa). The results revealed also that wood decaying and terrestrial saprotrophic taxa mainly characterize mixed forests while the occurrence of ectomycorrhizal taxa depends especially on the presence of ectomycorrhizal trees. The study gave evidence that the observed species richness and functional diversity of macrofungi in a defined area (plots), is strongly influenced by vascular plants composition. Each chosen forest type is characterized by a specific floristic composition and showed a corresponding and fairly predictable mycological composition.

Several ectomycorrhizal species showed preferences for particular forest stands. It must be said that the presence of a species was solely based on the observation of sporophores, i.e. not on the presence of mycelium or mycorrhized roots in the soil. Regarding the impact of soil, the study revealed that edaphic factors may affect the distribution and diversity of some EcM fungal fruiting bodies. The Brachystegia laurentii plant tree and its associated ectomycorrhizal fungi were mainly promoted by the content in extractable phosphorus while Gilbertiodendron dewevrei, Uapaca guineensis and Julbernardia seretii forests were mainly sustained by sand particle size. The aluminium acidity and the silt and clay particles were the most important edaphic parameters influencing the presence of EcM fungi associated with U. heudelotii. EcM fungi may have developed differently their ability to successfully colonize roots systems in relation with the availability of nutrients. Finally, the ethnomycological surveys demonstrated that wild mushrooms are used either for food (68 species), medicine (9 species), in a recreational context (2 species) or related to myths and beliefs (7 species). Women are more involved in harvesting and are the main holders of cultural aspects related to fungi. The Ngando people are the group having the highest ethnomycological expertise, which is expressed in their extensive cultural and practical use of fungi. In terms of usage, Pleurotus tuber-regium is the most important (MCSI=1.9 and p-value < 0.001). The species is used for food, as a medicine and more. Daldinia eschscholtzii is the most important (MUI=0.86 and p-value < 0.001) for medicinal applications. Wood-decaying taxa, i.e. saprotrophic species such as Schizophyllum commune, Auricularia cornea, A. delicata, Marasmius buzungolo and Lentinus squarrosulus are the most appreciated species for food.

We observed also that, felling of plant trees promotes the development of much desired saprotrophic fungi. At this point, in the province of Tshopo, edible mushrooms are an incentive for forest degradation rather than forest conservation. The cultivation of the locally appreciated saprotrophic fungi (except Schizophyllum) seems to be the only alternative to reduce harvest pressure in natural forests. Although easy to grow, Schizophyllum commune should not be recommended for consumption by some people as causing the severe “Schizophyllum disease” in some immunodeficient people.

 

The jury was composed of:

• Prof. Hippolyte NSHIMBA SEYA WA MALALE (University of Kisangani, D R Congo)
• Prof. Céphas MASUMBUKO NDABAGA (Official University of Bukavu, D R Congo)
• Prof. Jean-Marie KAHINDO MUHONGYA (University of Kisangani, D R Congo)
• Prof. Didy ONAUTSHU ODIMBA (University of Kisangani, D R Congo)
• Prof. OKUNGO LOTOKOLA (IFA-Yangambi, D R Congo)
• Prof. Corneille EWANGO EKOKINYA (University of Kisangani, D R Congo)
• Prof. Prosper SABONGO YANGAYOBO (University of Kisangani, D R Congo)

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