ABSTRACT
Hauke Harms, Lukas Y. Wick, and Dietmar Schlosser
31.1 INTRODUCTION
Fungi represent the dominant fraction of the microbial biomass in majority of all soil environments, and they contribute signi›cantly to the microbial species richness and biochemical functionality in soil ecosystems (Ritz and Young 2004). This dominance mirrors the superior capacity of saprotrophic fungi to degrade the major polymeric constituents of wood, leaves, and other plant materials (Kendrick 2000). As most soils are covered by vegetation, fungal symbiosis partners involved in the different forms of mycorrhiza also form an important part of the fungal soil community (Read and Perez-Moreno 2003). Soil fungi pervade their habitat, forming dense mycelial networks that constitute lifelines within the soil system. Through these networks, water, oxygen, nutrients, and basically all fungal biomass constituents and organic chemicals that fungi take up from their environment are transported (Furuno et al. 2012). Fungal hyphae act as an important transport path; the continuous nature of fungal networks permeating
an environment that is characterized by discontinuous surfaces has been identi›ed as an infrastructure along which further transport of water, air, and bacteria can take place and where an important part of all microbial activity takes place (Kohlmeier et al. 2005). The situation in groundwater aquifers is somewhat different, as in these water-saturated systems, fungi lose their advantage of being self-caterers. Nevertheless, fungi are present and thrive in these systems and are thus likely to ful›ll ecological functions (Solé et al. 2008a; Bärlocher 2016).
