Physiological and Morphological Features of Spruce and Beech Mycorrhizas in Natural Forest Systems

Abstract

Spruce mycorrhizas looked more healthy in two subalpine forest systems, where the predominant fungal sugar was mannitol, than in a lower situated mixed forest. Here, we found less mycorrhizal root tips per dry weight of fine roots, and that the predominant fungal sugar was trehalose. Beech trees in the mixed forest showed more mnycorrhiza, but reduced carbohydrate synthesis and content than spruce. Mycorrhizal frequency and sugar ratio (fungus/host) of spruce trees with reduced growth or with a transparent crown often higher than those of good growing and dense ones. Perhaps it is a strategy of trees with needle loss or reduced growth to shift the metabolic activities from the upper part of the tree to the root system.