Distribution, Mycorrhizal Infection, and Structure of Roots of Calcicole Floral Elements at Treeline, Bavarian Alps, Germany

Abstract

Mycorrhizal colonization and distribution of roots of alpine grasses, perennial herbs, and alpine dwarf shrubs in various microhabitats on rendzina soil were examined. Roots of constituent plants had been colonized by ectomycorrhizal (EM) and vesicular-arbuscular mycorrhizal (VAM) fungi. Commonly, miscellaneous septate (MS) endophytes were recorded. Phialophora radicola, Rhizoctonia sp., and Glomus tenue were the most frequent endophytes simultaneously associated with roots of individual host plants. A strong endomycorrhizal colonization of individual hosts was noted on patches supporting pioneer species like Festuca pumila and Alchemilla alpina. Sedge species with a welldeveloped root hair system were able to persist in the Seslerio-Semperviretum patches without typical VA mycorrhizae. Among the pioneering perennials in the Caricetum firmae patches ectomycorrhiza-forming woody species such as Dryas octopetala and Helianthemum nummularium ssp. grandiflorum dominated. Most of the perennial herbs on gravelly, partly denuded patches, and all dominant grasses in closed communities were highly colonized by VAM fungi. Results are discussed in terms of stress alleviation, selection of candidate host plants, and significance of native mycorrhizal fungi for revegetation of disturbed sites in high-elevation habitats.