title: Exploring the symbiont diversity of ancient western redcedars: arbuscular mycorrhizal fungi of long-lived hosts.
abstract: Arbuscular mycorrhizal fungi (AMF) are globally distributed, monophyletic root symbionts with ancient origins. Their contribution to carbon cycling and nutrient dynamics is ecologically important, given their obligate association with over 70% of vascular plant species. Current understanding of AMF species richness and community structure is based primarily on studies of grasses, herbs and agricultural crops, typically in disturbed environments. Few studies have considered AMF interactions with long-lived woody perennial species in undisturbed ecosystems. Here we examined AMF communities associated with roots and soils of young, mature and old western redcedar (Thuja plicata) at two sites in the old-growth temperate rainforests of British Columbia. Due to the unique biology of AMF, community richness and structure were assessed using a conservative, clade-based approach. We found 91 AMF OTUs across all samples, with significantly greater AMF richness in the southern site, but no differences in richness along the host chronosequence at either site. All host age classes harboured AMF communities that were overdispersed (more different to each other than expected by chance), with young tree communities most resembling old tree communities. A comparison with similar clade richness data obtained from the literature indicates that western redcedar AMF communities are as rich as those of grasses, tropical trees and palms. Our examination of undisturbed temperate old-growth rainforests suggests that priority effects, rather than succession, are an important aspect of AMF community assembly in this ecosystem.
authors.affiliation: Department of Forest and Conservation Science, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada.
authors.forename: Monika A
authors.initials: MA
authors.lastname: Gorzelak
authors.affiliation: School of Biological Sciences, University of Reading, Harborne Building, Whiteknights, Reading, RG6 8AS, UK.
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Pickles
authors.affiliation: Department of Biology, University of British Columbia Okanagan, Kelowna, BC, V1V 1V7, Canada.
authors.forename: Miranda M
authors.identifier: http://orcid.org/0000-0002-2503-8326
authors.initials: MM
authors.lastname: Hart
mesh_terms: D044822:Biodiversity; D001955:British Columbia; D005658:Fungi / Q000145:classification; D038821:Mycorrhizae / Q000145:classification*; D018517:Plant Roots / Q000382:microbiology; D065947:Rainforest; D012987:Soil; D012988:Soil Microbiology; D013559:Symbiosis; D029783:Thuja / Q000382:microbiology*
chemical_list: D012987:Soil
keywords: ancient forest; beta-diversity; chronosequence; microbial succession; phylogenetic diversity; western redcedar (Thuja plicata)