Quantification of symbiotic fungal biomass in ectomycorrhizas

为了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种不同的方法对不同树种不同树种的外生菌根共生真菌生物量进行了测定。(1)在光学显微镜下，对所有取样的外生菌根在横切面上的真菌鞘面积比(作为共生真菌生物量的指标)进行了测量。测定了赤松-黄牛乳杆菌外生菌根的菌丝横切面面积比。然后，剥离外生菌根真菌鞘，称其为共生真菌生物量的指标。(3)测定了外生菌根、真菌鞘和植物核心组织中真菌膜特异性麦角甾醇的含量，并将其含量换算为S…(1)苗木真菌鞘平均面积比针叶树为23.2(按重量换算，34.6)，阔叶树为26.4(按重量计算，39.3)%，表明阔叶树大于针叶树。苗木与成树之间的差异，赤松和青冈之间差异不显著，而冷杉和锯缘栎成株值显著大于苗木。(2)赤松-黄腐菌根共生真菌生物量占总生物量的41.9%。(3)以赤松-黄腐菌菌根的麦角甾醇含量估算，真菌鞘内共生真菌生物量为41.7%。(1)13种苗木和成树的外生菌根共生真菌生物量在35-40%之间，与Harley和McCady(1952)的Fagus sylvatica的共生真菌生物量的40%相近。(2)在外生菌根的核心植物组织中发现了较多的真菌生物量，占28.8%。(3)测定共生真菌生物量的周转时间，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。较少

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