Spatial structure of ectomycorrhizal trees in wooded savannas of Guineo-Sudanian ecozone in West Africa

Abstract

The Guineo-Sudanian and Sudanian zones are home to predominantly ectomycorrhizal (EcM) plant communities dominated by members of the families Fabaceae (subfamily Ceasalpinioidae), Phyllanthaceae and Dipterocarpaceae. Numerous studies have shown that the aggregation of EcM trees is facilitated in part by the shared mycelial networks of EcM fungi. Mycelial networks involving mature trees would thus directly affect the survival of the seedlings of EcM trees and, thereby, the spatial structuring of the trees. In this study, we investigated the structure and spatial interactions of three vegetation types dominated by different EcM trees, namely, Isoberlinia doka, I. tomentosa and Uapaca togoensis. Three 50 m × 50 m plots were installed for each vegetation type. All EcM trees present in each plot were counted for estimation of density. Ripley’s second order function K was used to estimate the spatial structure of EcMs trees. Spatial distribution of trees differed between species. Repulsion occurred at scales of 1 to 5 m between the different EcM trees species. By sharing nutrient through mycelial network, repulsion mechanisms observed during interaction between plants should have been cancelled but this was not observed in this study.