Underground Explorers

Plant-fungal interactions, such as mycorrhizal symbiosis, are major determinants of plant biogeographic range size, population dynamics and plant community composition. In tropical forest ecosystems of oceanic islands, native and endemic plant communities tend to be replaced by introduced and invasive plant communities resulting in significant changes in the overstory, understory and forest floor. However, in these regions of the world, the impact of biological invasions on soil fungal biodiversity is poorly documented. In this project, we propose to (1) conduct a molecular inventory of soil fungi in the rainforests of Mo'orea, one of the high islands of French Polynesia and (2) assess the impact of the invasive plants Miconia calvescens and Spathodea campanulata on these fungal communities.

The taxonomic inventory of fungal species will be based on high-throughput sequencing techniques of ribosomal DNA (metabarcoding). It will be conducted on DNA extracted from the soils of the high altitude rainforest called "cloud forest" and in the low altitude mesophilic forest on an experimental site listed as a natural area of ecological and heritage interest (ENIEP of Opunohu). The aim is to evaluate the impact of biotic factors (e.g. presence of invasive plants) and abiotic factors (e.g. level of precipitation) on the composition and richness of soil fungi communities (saprotrophs and mycorrhizal symbiotics).A better knowledge of fungal communities in forest soils and endemic tree roots should inform us on the effects of fungal microbial communities on the vulnerability and resilience of tropical rainforests to plant invasions, in a context of climate change.