Strong effect of climate on ectomycorrhizal fungal composition: evidence from range overlap between two mountains

Abstract

Separating the effects of environmental factors and spatial distance on microbial composition is difficult when these factors covary. We examined the composition of ectomycorrhizal (EM) fungi along elevation gradients on geographically distant mountains to clarify the effect of climate at the regional scale. Soil cores were collected from various forest types along an elevation gradient in southwestern Japan. Fungal species were identified by the internal transcribed spacer regions of the rDNA using direct sequencing. The occurrence of fungal species in this study was compared with a previous study conducted on a mountain separated by B550 km. In total, we recorded 454 EM fungi from 330 of 350 soil cores. Forty-seven fungal species (B20% of the total excluding singletons) were shared between two mountains, mostly between similar forest types on both mountains. Variation partitioning in redundancy analysis revealed that climate explained the largest variance in EM fungal composition. The similarity of forest tree composition, which is usually determined by climatic conditions, was positively correlated with the similarity of the EM fungal composition. However, the lack of large host effects implied that communities of forest trees and EM fungi may be determined independently by climate. Our data provide important insights that host plants and mutualistic fungi may respond to climate change idiosyncratically, potentially altering carbon and nutrient cycles in relation to the plant-fungus associations.

Ectomycorrhizal fungal diversity and community structure associated with cork oak in different landscapes

“…Another indication of northern ECMF heterogeneity is given by the Mantel test statistic that described a significant correlation between ECMF similarity and geographic distance for the closer northern forests (109 km apart) but a non-significant correlation between the more separated southern forests (150 km apart). These results suggest that distance is not the main driver for ECMF occurrence, especially for the driest regions, and agree with Miyamoto et al (2015) who described geographic distance as a minor driver of ECMF community structure at a regional scale. The composition of ECMF communities is strongly influenced by biotic and abiotic conditions.…”

Soil propagule banks of ectomycorrhizal fungi share many common species along an elevation gradient

“…Moreover, frequently occurring fungal taxa differed between Betula and Pinus (Collier and Bidartondo 2009) and between Pinus and Pseudotsuga bioassay seedlings (Pickles et al 2015). Thus, assayed soil propagule communities may differ between bioassay hosts, which would contrast to the weak influences of host trees on EM fungal composition on existing roots in our previous study (Miyamoto et al 2015).…”

“…Ishizuchi, western Japan in 2012 (33°44 -33°46 N, 133°07 -133°09 E; Miyamoto et al 2015). All sites were located in closedcanopy natural forests with minimum human disturbances.…”

“…In the past few years, several studies have documented that the community composition of EM fungi changed along elevation gradients and climate was a primary determinant of such patterns Miyamoto et al 2014Miyamoto et al , 2015Jarvis et al 2015). These studies demonstrated a high turnover in the species composition along the elevation gradients, while assayed soil propagule communities of EM fungi are expected to be homogeneous within a narrow region (Izzo et al 2006b).…”

“…Because of the critical roles of EM fungi in nature, a great deal of attention has been devoted to understand the mechanisms of community structure for this functional group . Community structure is determined by both biotic and abiotic factors, including host identity (Ishida et al 2007; Morris et al 2009), climate Miyamoto et al 2015), soil properties (Aponte et al 2010;Cox et al 2010), succession (Twieg et al 2007), and geographic distance (Lilleskov et al 2004;Pickles et al 2012).…”