Differentiation of ectomycorrhizal morphology in Abies faxoniana along an elevation gradient in a subalpine forest of western Sichuan Province, China

Abstract

Ectomycorrhizal fungi are an important group of symbiotic fungi beneficial to plant growth and their environmental adaptation. An explicit clarification of the trait of ectomycorrhizal fungi would facilitate our understanding of plant responses to environmental change. We set up sampling plots at five elevations (2850, 3000, 3194, 3413, 3593 m) in the Balong Mountain within the Wolong Nature Reserve of Sichuan Province, and collected cubic soil samples (10 cm×10 cm×10 cm) from those plots by point centered quarter method. Based on examination of the morphological types and diversity of ectomycorrhizal roots of Abies faxoniana in each soil sample, we examined the variations in morphological traits of ectomycorrhizal roots of A. faxoniana along the elevational gra-dient and the effects of soil environmental factors. Results showed that: 1) The major ectomycorrhizae of A. faxoniana in Wolong Nature Reserve was orange or yellow in color, with smooth mantle and no or few extensional hyphae, and cylindric or inflated root tips. This type of ectomycorrhizae occurred with highest rate of colonization (12.4%) in the study area. 2) With the increases of elevation, the morphological diversity of ectomycorrhizae in A. faxoniana declined and the morphological types per cubic soil sample significantly decreased. 3) There were significant differences between the ectomycorrhizae of contact exploration type (CE) and short distance exploration type (SDE) at different elevations, while the colonization rate of CE increased significantly with elevation. 4) Soil factors drove the variations of ectomycorrhizal morphology in A. faxoniana along the elevational gradient. Redundancy analysis (RDA) showed that soil total nitrogen (TN), soil temperature (Ts), soil water content (SWC), pH, soil acid phosphatase (ACP) and soil total phosphorus (TP) had significant effects on ectomycorrhizal morphology in A. faxoniana, among which TN and Ts being the greatest and explaining 5.4% and 4.9% of the total variations. Our results clari-fied the variations in the occurrence of ectomycorrhizal morphology in A. faxoniana along elevational gradient, which provided scientific evidence for further studying the mechanisms underlying the responses to environmental changes in mycorrhizal strategy in coniferous species of subalpine forests.