Leaf and Root-Associated Fungal Assemblages Do Not Follow Similar Elevational Diversity Patterns

Abstract

The diversity of fungi along environmental gradients has been little explored in contrast to plants and animals. Consequently, environmental factors influencing the composition of fungal assemblages are poorly understood. The aim of this study was to determine whether the diversity and composition of leaf and root-associated fungal assemblages vary with elevation and to investigate potential explanatory variables. High-throughput sequencing of the Internal Transcribed Spacer 1 region was used to explore fungal assemblages along three elevation gradients, located in French mountainous regions. Beech forest was selected as a study system to minimise the host effect. The variation in species richness and specific composition was investigated for ascomycetes and basidiomycetes assemblages with a particular focus on root-associated ectomycorrhizal fungi. The richness of fungal communities associated with leaves or roots did not significantly relate to any of the tested environmental drivers, i.e. elevation, mean temperature, precipitation or edaphic variables such as soil pH or the ratio carbon∶nitrogen. Nevertheless, the ascomycete species richness peaked at mid-temperature, illustrating a mid-domain effect model. We found that leaf and root-associated fungal assemblages did not follow similar patterns of composition with elevation. While the composition of the leaf-associated fungal assemblage correlated primarily with the mean annual temperature, the composition of root-associated fungal assemblage was explained equally by soil pH and by temperature. The ectomycorrhizal composition was also related to these variables. Our results therefore suggest that above and below-ground fungal assemblages are not controlled by the same main environmental variables. This may be due to the larger amplitude of climatic variables in the tree foliage compared to the soil environment.

Latent infection of Biscogniauxia nummularia in Fagus sylvatica: a possible bioindicator of beech health conditions

“…Recently, it was shown that the composition of leaf-associated fungi on F. sylvatica is correlated primarily with the annual mean temperature (Cordier et al 2012, Coince et al 2014. In the present work, the detection B. nummularia DNA in symptomless tissue of beech showed a significant decreasing trend as the mean precipitation of the month preceding the sampling increases (R 2 = 0.86), i.e., the amount of latent infection increased with decreasing precipitation.…”

Controls of nitrogen cycling evaluated along a well‐characterized climate gradient

“…Bryant et al (2008) found that Acidobacteria decreased in richness over a change of 1000 m elevation in the Rocky Mountains. Similarly mixed results have been found for Fungi, with evidence for greatest richness at mid-elevations due to range overlap (Bahram et al 2012, Coince et al 2014, Miyamoto et al 2014, lack of change with elevation (Zimmerman and Vitousek 2012, Coince et al 2014, Jarvis et al 2015, decreased richness at higher elevations (Looby et al 2016), or increased richness at higher elevations (Pellissier et al 2014). Fewer studies have examined Archaea, but work on two Japanese mountains found a mid-elevation peak in OTU richness (Singh et al 2012, Singh et al 2016).…”

Forest tree genomics: 10 achievements from the past 10 years and future prospects

“…By opening the microbial world to ecologists, the next-gen revolution also gave rise to larger scale studies, aimed at assessing the influence of climate and other global change components on tree-associated microbial communities. The analysis of beech-associated fungal communities along elevation gradients suggested that the air temperature is a major structuring factor of foliar communities (Cordier et al 2012b) but not of their below-ground counterparts (Coince et al 2014). A comparison between urban and non-urban stands revealed significant effects of anthropogenic activities on foliar fungal communities of Quercus macrocarpa (Jumpponen and Jones 2010).…”