Decomposing ability of diverse litter-decomposer macrofungi in subtropical, temperate, and subalpine forests

摘要

An integrative survey was conducted on the ability of litter-decomposing macrofungi (LDM) from forests of different climatic regions to decompose litter materials and recalcitrant compounds in the litter under pure culture conditions. A total of 75 isolates in six families of LDM from subtropical, cool temperate (CT), and subalpine (SA) forests in Japan were tested for their ability to decompose a total of eight litter types that are major substrates for macrofungi at each site. The mass loss of the litter (% original mass) during incubation for 12 weeks at 20 °C ranged from −3.1 % to 54.5 %. Macrofungi originated from forests of different climatic regions exhibited similar decomposing abilities, but the SA isolates caused negligible mass loss of Abies needles, possibly due to inhibitory compounds. Decomposing activity for recalcitrant compounds (as acid-unhydrolyzable residues, AUR) was found in many macrofungal isolates. The isolates of Marasmiaceae were generally more able to cause selective decomposition of AUR than those of Mycenaceae and to decompose AUR in partly decomposed materials. The isolates of Xylariaceae had lower ligninolytic activity than those of Basidiomycetes. The AUR mass loss caused by CT isolates was significantly lower in nitrogen-rich beech litter than in its nitrogen-poor counterpart, suggesting a retarding effect of nitrogen on AUR decomposition, which was obvious for Mycenaceae. The effect of fungal family was generally more significant than that of litter type, suggesting that possible changes in the composition of fungal assemblages influence their functioning more than changes in the quality of substrates.