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.与不同菌丝发育水平及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长，可为森林碳循环动态研究提供关键科学启示。本研究对采自5株经¹³CO₂标记的欧洲云杉（Picea abies）周边0~6 m、6~12 m、12~18 m及>18 m区域的外生菌根真菌子实体开展了δ¹³C同位素模式分析。在0~6 m区域内，菌丝发育程度较高与较低的真菌类群分别从标记树中获取了25±7%与48±7%的碳源；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中获取了74±6%与5±6%的碳源。子实体的δ¹³C值与子实体采收前17~21天的太阳辐射呈显著正相关。上述研究结果表明：其一，子实体形成所需的碳积累与转运过程需耗时数周；其二，欧洲云杉的光合产物优先分配给与针叶树共生的真菌类群；其三，菌丝发育程度较高的真菌类群相比发育程度较低的类群，碳同化的空间范围更广。