Quantification of symbiotic fungal biomass in ectomycorrhizas

为定量评价外生菌根真菌在森林生态系统碳循环中的作用，采用3种不同方法对北海道和广岛两县亚北极-暖温带森林中6株针叶树和7株阔叶树幼苗、2株针叶树和2株阔叶树成年树外生菌根共生真菌生物量进行了定量分析。(1)在光学显微镜下测量了所有外生菌根横切面上的菌鞘面积比（作为共生真菌生物量的指标）。测定了赤松-褐乳牛肝菌成株外生菌根横切面上菌鞘面积比。然后，（2）将外生菌根的菌鞘剥离，称重作为共生真菌生物量的指标。(3)测定了外生菌根、真菌鞘和核心植物组织中的真菌膜特异性麦角甾醇，并将其含量换算成s 关于我们 共生真菌生物量。(1)针叶树和阔叶树幼苗真菌鞘的平均面积比分别为23.2（换算重量为34.6）%和26.4（换算重量为39.3）%，阔叶树大于针叶树。在成树与幼苗之间的差异上，赤松和水青冈之间差异不显著，而冷杉和锯齿栎成树的差异显著大于幼苗。(2)赤松-黄乳牛肝菌外生菌根共生真菌生物量占总生物量的41.9%. (3)以赤松-褐黄乳牛肝菌外生菌根菌鞘中麦角甾醇含量估算的共生真菌生物量为41.7%。外生菌根的核心植物组织中真菌生物量最大，占28.8%。(1)13个树种的苗木和成木外生菌根共生真菌生物量在35- 40%之间，与哈雷和McCready（1952）的森林水青冈（Fagussylvatica）的40%相近。(2)有趣的是，外生菌根的核心植物组织中真菌生物量较大，占28.8%。(3)下一步是确定共生真菌生物量周转时间，以定量阐明外生菌根真菌在森林生态系统碳循环中的作用。少

To estimate quantitatively the role of ectomycorrhizal fungi in carbon cycling of forest ecosystem, symbiotic fungal biomass in ectomycorrhiza of several tree species with different ages were quantified by 3 different methods.Six coniferous and 7 broad-leaved seedlings, and 2 coniferous and 2 broad-leaved adult trees were sampled in sub-arctic to warm-temperate forests in Hokkaido and Hiroshima prefectures. (1) For all sampled ectomycorrhizas, area ratios of fungal sheath (as index of symbiotic fungal biomass) in transverse section of ectomycorrhiza was measured under optical microscope. For adult Pinus densiflora - Suillus luteus ectomycorrhiza, area ratio of fungal sheath in transverse section of ectomycorrhiza was also measured. Then, (2) fungal sheath of ectomycorrhiza was peeled out, and weighed as index of symbiotic fungal biomass. (3) Fungal membrane specific ergosterol in ectomycorrhiza, fungal sheath and core plant tissue were determined, and their contents were converted to s … More ymbiotic fungal biomass.(1) The averaged area ratios of fungal sheath of seedlings were 23.2 (converted value in weight basis, 34.6) for coniferous, and 26.4 (in weight basis, 39.3)% for broad-leaved trees, respectively, showing the value for broad-leaved trees was larger than that for coniferous trees. About the differences between seedlings and adult trees, in Pinus densiflora and Fagus crenata the values were not significantly different each other, but in Abies firma and Quercus serrata the values of adult trees were significantly larger than those of seedlings. (2) Symbiotic fungal biomass in weight basis of Pinus densiflora - Suillus luteus ectomycorrhiza was 41.9%. (3) Symbiotic fungal biomass in fungal sheath estimated from ergosterol content of Pinus densiflora - Suillus luteus ectomycorrhiza was 41.7%. Larger amount of fungal biomass, 28.8%, was found in core plant tissue of ectomycorrhiza.(1) Symbiotic fungal biomass of ectomycorrhizas of 13 tree species of seedlings and adult trees were in the range of 35-40%, which were similar to 40% of Fagus sylvatica of Harley and McCready (1952). (2) It is very interesting that larger amount of fungal biomass, 28.8%, was found in core plant tissue of ectomycorrhiza. (3) Next step is the determination of the turnover time of symbiotic fungal biomass to clarify quantitatively the role of ectomycorrhizal fungi in carbon cycling of forest ecosystem. Less