菌類をめぐる窒素動態に関する研究で著名なNew Hampshire大のErik Hobbie博士にご講演いただきます。皆さま奮ってご参加ください。
講演タイトル：Strategies and resource acquisition of ectomycorrhizal fungi and wood decay fungi in forest ecosystems
We will have a seminar by Dr. Erik Hobbie. He studies fungal functioning by using nitrogen dynamics. I hope many people come and join us. Polycom from branch office is available. I am glad if you inform me befor when you want to attend via Polycom (we will connect to HD1).
Date: 1 October 15:00～16:00
Place: Large conferece room (1st floor) in Field Science Center for Northern Biosphere (Experiment Farm)
Title: Strategies and resource acquisition of ectomycorrhizal fungi and wood decay fungi in forest ecosystems
We present two case studies of fungal functioning in forest ecosystems. In the first, we investigated functional differences in six taxa of decay fungi during a long-term log decomposition study (Oregon, USA) by studying elemental, isotopic, and compositional patterns in wood, cellulose, and sporocarps. Partitioning between protein and non-protein pools in mycelia prior to sporocarp formation controlled sporocarp δ15N relative to N sources. Radiocarbon measurements separated fungi into heartwood colonizers (Fomitopsis and Hericium, ~60-year-old carbon) and sapwood colonizers (Mycena (7 years), Hypholoma (11 years), and Trametes (11 years). Mycena and Hypholoma appeared to assimilate some 13C-enriched sucrose in sapwood rather than just cellulose. The six taxa varied widely in their chemical composition, as assessed by pyrolysis GC-MS; these compositional differences correlated with functional growth strategies. From these measurements, we improved the quantitative and conceptual understanding of functional differences of wood decay fungi. In the second study, we assessed how nitrogen (N) availability affected ectomycorrhizal functioning in two long-term (6-40 years) N addition experiments in Pinus sylvestris stands in Sweden. Sporocarp production declined dramatically with N fertilization but recovered slowly after fertilization stopped. Both sporocarp C/N and soil C/N increased with fertilization, implying that N uptake per unit fungal growth increased and then declined after fertilization had stopped. Fungal and soil d15N patterns across treatments identified fungal N sources, with N acquisition primarily from the S horizon for Paxillus involutus and Suillus variegatus, from the F horizon for four Cortinarius taxa and Lactarius rufus, and from the H horizon for Cortinarius traganus and Russula aeruginea. Taxa with proteolytic capabilities were particularly sensitive to N fertilization. These analyses illustrated that responses of fungal taxa across these fertilization gradients depended on the horizon of N acquisition and on N acquisition strategies.
Contact: Karibu Fukuzawa
Tel: 01656-5-3216 (Nakagawa Experimental Forest)