Fungal carbon sources in a pine forest: evidence from a 13C-labeled global change experiment

Erik A. Hobbie; Kirsten S. Hofmockel; Linda T.A. Van Diepen; Erik Lilleskov; Andrew P. Oiumette; Adrien C. Finzi

doi:10.1016/j.funeco.2013.11.001

Treesearch

Fungal carbon sources in a pine forest: evidence from a ¹³C-labeled global change experiment

Formally Refereed

Authors:

Erik A. Hobbie, Kirsten S. Hofmockel, Linda T.A. Van Diepen, Erik Lilleskov, Andrew P. Oiumette, Adrien C. Finzi

Year:

2014

Type:

Scientific Journal

Station:

Northern Research Station

DOI:

https://doi.org/10.1016/j.funeco.2013.11.001

Source:

Fungal Ecology. 10: 91-100.

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Abstract

We used natural abundance ¹³C:¹²C (δ¹³C) and 8 yr of labeling with ¹³C-depleted CO₂ in a Pinus taeda Free Air CO₂ Enrichment (FACE) experiment to investigate carbon sources of saprotrophic fungi, ectomycorrhizal fungi, and fungi of uncertain life history. Sporocarp δ¹³C identified Sistotrema confluens as ectomycorrhizal, as suspected previously from morphological characteristics. Saprotrophic δ¹³C declined by 2 ⁰/_{00 —}13 ⁰/₀₀ between ambient to elevated CO₂ treatments and corresponded to different carbon sources, including surface litter (Rhodocollybia, Mycena), pine cones (Baeospora), wood (Gymnopilus, Pholiota), and soil (Ramariopsis). Ectomycorrhizal fungi, foliage, and surficial litter declined 12 ⁰/₀₀ in δ¹³C between ambient and elevated treatments, confirming that these fungi depend on recent photosynthate. The δ¹³C of ectomycorrhizal genera correlated between treatments with a slope (4.3 ± 1.2) greater than the expected value of one. This suggested that Inocybe and Cortinarius incorporated some pre-treatment, soil-derived carbon (presumably from amino acids) whereas Lactarius and Russula only incorporated current-year photosynthate or recent, litter-derived carbon. Combining natural abundance and tracer ¹³C measurements proved a powerful technique to examine carbon sources of different fungi.

Keywords

Carbon isotope, Carbon source, Duke Forest, Ectomycorrhizal fungi, Exploration type, Global change, Organic nitrogen, Saprotrophic fungi

Citation

Hobbie, Erik A.; Hofmockel, Kirsten S.; Van Diepen, Linda T.A.; Lilleskov, Erik A.; Oiumette, Andrew P.; Finzi, Adrien C. 2014. Fungal carbon sources in a pine forest: evidence from a ¹³C-labeled global change experiment. Fungal Ecology. 10: 91-100.