Carbon isotopes in sporocarps from the Swiss conifer web-FACE, 2010-2011

The spatial extent and lag time of carbon fluxes to ectomycorrhizal fungi associated with differing hyphal development and hosts could provide insights into forest carbon dynamics. In ectomycorrhizal sporocarps collected at 0-6, 6-12, 12-18, and > 18 m from five 13CO2-labeled Picea abies, δ13C patterns were analyzed. At 0-6 m, taxa with greater or lesser hyphal development derived 25 ± 7% and 48 ± 7% of their carbon from labeled trees, respectively. At 6-12 m, conifer-associated and other-associated sporocarps derived 74 ± 6% and 5 ± 6% of their carbon from labeled trees, respectively. Sporocarp δ13C correlated positively with solar radiation for 17-21 days prior to sporocarp harvest. These patterns indicated that (1) carbon accumulation and movement for sporocarp formation took several weeks, (2) Picea photosynthate was preferentially allocated to conifer-associated fungi, and (3) taxa of greater hyphal development assimilated carbon more widely than taxa of less hyphal development.与不同菌丝发育程度及宿主相关的外生菌根真菌（ectomycorrhizal fungi）的碳通量（carbon fluxes）空间范围与滞后时间，可为森林碳动态（forest carbon dynamics）研究提供新见解。本研究对采集自5株经13CO2标记的挪威云杉（Picea abies）周边0-6 m、6-12 m、12-18 m及>18 m区域的外生菌根子实体（ectomycorrhizal sporocarps）的碳同位素比值（δ13C）特征进行了分析。在0-6 m区域内，菌丝发育程度较高与较低的分类类群分别从标记树木中获取25±7%与48±7%的碳。在6-12 m区域内，与针叶树共生及与其他宿主共生的子实体分别从标记树木中获取74±6%与5±6%的碳。子实体的δ13C值与子实体采收前17-21天的太阳辐射（solar radiation）呈正相关。上述结果表明：（1）子实体形成所需的碳积累与运移过程需耗时数周；（2）挪威云杉的光合产物（photosynthate）优先分配给与针叶树共生的真菌类群；（3）菌丝发育程度较高的分类类群的碳同化范围较菌丝发育程度较低的类群更广。