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Title: Tree mycorrhizal type predicts within‐site variability in the storage and distribution of soil organic matter
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 inECM‐dominated forests. However, an incipient hypothesis predicts that systems with rapid decomposition—e.g. mostAM‐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 ofECM‐dominance in three temperate forests. By focusing on sites whereAM‐ andECM‐plants co‐occur, our analysis controls for climatic factors that covary with mycorrhizal dominance across broad scales. We found that whileECMstands contain moreSOMin topsoil,AMstands contain moreSOMwhen subsoil to 1 m depth is included. Biomarkers and soil fractionations reveal that these patterns are driven by an accumulation of microbial residues inAM‐dominated soils. Collectively, our results support emerging theory onSOMformation, 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 ofSOM.

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NSF-PAR ID:
10056767
Author(s) / Creator(s):
 ;  ;  ;  ;  ;  
Publisher / Repository:
Wiley-Blackwell
Date Published:
Journal Name:
Global Change Biology
Volume:
24
Issue:
8
ISSN:
1354-1013
Page Range / eLocation ID:
p. 3317-3330
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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