Hyphal length in the forest floor and soil of subtropical, temperate, and subalpine forests

Abstract

Fungi are a major component of soil biota in terrestrial ecosystems of various climatic regions, but few studies have compared the effects of soil layer and season on their abundance between sites with different humus forms and climatic conditions. In the present study, the hyphal length in the forest floor and soil was investigated in subtropical (ST), cool temperate (CT), and subalpine (SA) forests in Japan with an agar film method. The primary aim was to describe the seasonal variations in hyphal length in different layers of mull and moder humus forms in forests of these three climatic regions. The total hyphal length was generally higher in CT than in ST and SA and decreased with the soil depth. Seasonal changes in total hyphal length were observed in ST and in the lower slope of CT where mull humus developed. The length of darkly pigmented hyphae and the proportion of them relative to the total hyphal length were higher at the upper slope of the CT forest (moder humus) than at the other sites, and decreased in the order F > L > A layers. Clamp-bearing hyphal length in Basidiomycota accounted for as much as 19 % of the total hyphal length and decreased with the depth of the forest floor and soil in all study sites. Seasonal changes of hyphal length and the layer × month interaction were significant on mull but not on moder humus, suggesting that hyphal length was more sensitive to season in mull than in moder humus.