Abstract
Forest soils store large amounts of carbon (C) and nitrogen (N), yet how predicted shifts in forest composition will impact long-term C and N persistence remains poorly understood. A recent hypothesis predicts that soils under trees associated with arbuscular mycorrhizas (AM) store less C than soils dominated by trees associated with ectomycorrhizas (ECM), due to slower decomposition in ECM-dominated forests. However, an incipient hypothesis predicts that systems with rapid decomposition—e.g. most AM-dominated forests—enhance soil organic matter (SOM) stabilization by accelerating the production of microbial residues. To address these contrasting predictions, we quantified soil C and N to 1 m depth across gradients of ECM-dominance in three temperate forests. By focusing on sites where AM- and ECM-plants co-occur, our analysis controls for climatic factors that covary with mycorrhizal dominance across broad scales. We found that while ECM stands contain more SOM in topsoil, AM stands contain more SOM when subsoil to 1 m depth is included. Biomarkers and soil fractionations reveal that these patterns are driven by an accumulation of microbial residues in AM-dominated soils. Collectively, our results support emerging theory on SOM formation, demonstrate the importance of subsurface soils in mediating plant effects on soil C and N, and indicate that shifts in the mycorrhizal composition of temperate forests may alter the stabilization of SOM.
Original language | English |
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Pages (from-to) | 3317-3330 |
Number of pages | 14 |
Journal | Global Change Biology |
Volume | 24 |
Issue number | 8 |
DOIs | |
State | Published - Aug 2018 |
Externally published | Yes |
Funding
This material is based upon work supported by the Smithsonian Tropical Research Institute. The Center for Tropical Forest Science-Forest Global Earth Observatory supported the establishment of these plots and the CTFS-ForestGEO Grants Program funded the soil analyses. LDW is part of Indiana University’s Research and Teaching Preserve. We also acknowledge the support of the U.S. Department of Energy Office of Biological and Environmental Research, Terrestrial Ecosystem Science Program (Award# DESC0016188), the US National Science Foundation Ecosystem Studies Program (1153401), and the National Natural Science Foundation of China (41471218). We thank D. Agudo, T. Beresky, D. Du, P. Esco-bar, L. Podzikowski, X. Shen, and the many technicians who contributed to this project in the field and laboratory, and we thank B. McShea, N. Bourg, and G. Parker for coordinating and sharing data from the forest inventories at SCBI and SERC. Lastly, we thank members of the Phillips lab, M. Bradford, the anonymous reviewers, and the editor, F. Cotrufo, for their helpful comments. The authors declare no conflict of interest. This material is based upon work supported by the Smithsonian Tropical Research Institute. The Center for Tropical Forest Science-Forest Global Earth Observatory supported the establishment of these plots and the CTFS-ForestGEO Grants Program funded the soil analyses. LDW is part of Indiana University's Research and Teaching Preserve. We also acknowledge the support of the U.S. Department of Energy Office of Biological and Environmental Research, Terrestrial Ecosystem Science Program (Award# DE-SC0016188), the US National Science Foundation Ecosystem Studies Program (1153401), and the National Natural Science Foundation of China (41471218). We thank D. Agudo, T. Beresky, D. Du, P. Escobar, L. Podzikowski, X. Shen, and the many technicians who contributed to this project in the field and laboratory, and we thank B. McShea, N. Bourg, and G. Parker for coordinating and sharing data from the forest inventories at SCBI and SERC. Lastly, we thank members of the Phillips lab, M. Bradford, the anonymous reviewers, and the editor, F. Cotrufo, for their helpful comments.
Funders | Funder number |
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CTFS-ForestGEO | |
U.S. Department of Energy Office of Biological and Environmental Research | DESC0016188 |
US National Science Foundation | 1153401 |
Connecticut State Emergency Response Commission | |
Indiana University | |
Smithsonian Tropical Research Institute | |
National Natural Science Foundation of China | 41471218 |
Keywords
- MEMs hypothesis
- amino sugars
- decomposition
- mineral-associated
- mycorrhizal fungi
- soil carbon
- soil depth
- soil nitrogen
- temperate forest