How ectomycorrhizal communities vary from natural to urban ecosystems: Quercus humboldtii as a study case in the tropical Andes

Abstract

Urban landscapes are becoming more important due to the accelerated population growth and increasing urbanization. Urban ecosystems serve as home to diverse plant and fungal communities. However, studies focusing on the diversity and structure of biological communities are uncommon in this habitat. In Colombia, Quercus humboldtii Bonpl. is a conspicuous ectomycorrhizal species present in tropical montane forests that hosts a high diversity of ectomycorrhizal fungi in its roots. Quercus humboldtii is commonly used as an urban tree in Bogotá, but the ectomycorrhizal communities of this species have not yet been studied in urban ecosystems. We studied how the ectomycorrhizal fungal communities associated with this tree change between natural and urban ecosystems. Roots of 24 trees were sampled in two sites, Chicaque Natural Reserve (natural) and three neighborhoods of Bogotá city (urban). Using Illumina sequencing, the ITS1 region of all root associated fungi was amplified and analyzed using both OTUs and ASVs bioinformatics pipelines. We found 949 OTUs in Bogotá and 514 OTUs in Chicaque. We didn’t find significant differences in the species richness between Bogotá and Chicaque sites based on Fisher’s alpha or species-accumulation curves. In Chicaque communities, the most abundant genera were Russula and Lactarius, while Scleroderma, Hydnangium, and Trechispora were highly abundant in Bogotá. An NMDS analysis showed that samples from the natural site had a significantly different community composition compared with urban trees. Our results highlight the importance of Quercus trees as reservoirs of ectomycorrhizal fungal diversity in Bogotá.