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共生宿主相关的外生菌根真菌（ectomycorrhizal fungi）的碳通量空间范围与滞后时间，可为森林碳动态研究提供重要科学见解。本研究对距离5株经13CO2标记的欧洲云杉（Picea abies）0-6 m、6-12 m、12-18 m及>18 m区域内采集的外生菌根子实体的δ13C特征进行了分析。在0-6 m区域内，菌丝发育程度较高和较低的真菌类群分别从标记母树中获取25 ± 7%与48 ± 7%的碳源；在6-12 m区域内，与针叶树共生的子实体类群及其他共生类群的子实体分别从标记母树中获取74 ± 6%与5 ± 6%的碳源。子实体的δ13C值与子实体收获前17至21天的太阳辐射呈显著正相关。上述研究结果表明：（1）子实体形成所需的碳积累与转运过程需耗时数周；（2）欧洲云杉的光合产物优先分配给与针叶树共生的真菌；（3）菌丝发育程度较高的类群的碳同化范围较菌丝发育程度较低的类群更为广泛。