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Title: Dirt cheap: an experimental test of controls on resource exchange in an ectomycorrhizal symbiosis
Summary

To distinguish among hypotheses on the importance of resource‐exchange ratios in outcomes of mutualisms, we measured resource (carbon (C), nitrogen (N), and phosphorus (P)) transfers and their ratios, betweenPinus taedaseedlings and two ectomycorrhizal (EM) fungal species,Rhizopogon roseolusandPisolithus arhizusin a laboratory experiment.

We evaluated how ambient light affected those resource fluxes and ratios over three time periods (10, 20, and 30 wk) and the consequences for plant and fungal biomass accrual, in environmental chambers.

Our results suggest that light availability is an important factor driving absolute fluxes of N, P, and C, but not exchange ratios, although its effects vary among EM fungal species. Declines in N : C and P : C exchange ratios over time, as soil nutrient availability likely declined, were consistent with predictions of biological market models. Absolute transfer of P was an important predictor of both plant and fungal biomass, consistent with the excess resource‐exchange hypothesis, and N transfer to plants was positively associated with fungal biomass.

Altogether, light effects on resource fluxes indicated mixed support for various theoretical frameworks, while results on biomass accrual better supported the excess resource‐exchange hypothesis, although among‐species variability is in need of further characterization.

 
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Award ID(s):
1119865
NSF-PAR ID:
10390367
Author(s) / Creator(s):
 ;  ;  ;  ;  
Publisher / Repository:
Wiley-Blackwell
Date Published:
Journal Name:
New Phytologist
Volume:
237
Issue:
3
ISSN:
0028-646X
Format(s):
Medium: X Size: p. 987-998
Size(s):
["p. 987-998"]
Sponsoring Org:
National Science Foundation
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