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Favorable effect of mycorrhizae on biomass production efficiency exceeds their carbon cost in a fertilization experiment
Author(s) -
Verlinden Melanie S.,
Ven Arne,
Verbruggen Erik,
Janssens Ivan A.,
Wallander Håkan,
Vicca Sara
Publication year - 2018
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.1002/ecy.2502
Subject(s) - mesocosm , nutrient , photosynthesis , biomass (ecology) , phosphorus , agronomy , biology , photosynthetic efficiency , ecosystem , botany , chemistry , ecology , organic chemistry
Biomass production efficiency ( BPE ), the ratio of biomass production to photosynthesis, varies greatly among ecosystems and typically increases with increasing nutrient availability. Reduced carbon partitioning to mycorrhizal fungi (i.e., per unit photosynthesis) is the hypothesized underlying mechanism, as mycorrhizal abundance and plant dependence on these symbionts typically decrease with increasing nutrient availability. In a mesocosm experiment with Zea mays , we investigated the effect of nitrogen (N) and phosphorus (P) addition and of mycorrhizal inoculation on BPE . Photosynthesis and respiration were measured at mesocosm scale and at leaf scale. The growth of arbuscular mycorrhizal fungi ( AMF ) was assessed with ingrowth bags while also making use of the difference in δ 13 C between C 4 plants and C 3 soil. Mesocosms without AMF , that is, with pasteurized soil, were used to further explore the role of AMF . Plant growth, photosynthesis, and BPE were positively affected by P, but not by N addition. AMF biomass also was slightly higher under P addition, but carbon partitioning to AMF was significantly lower than without P addition. Interestingly, in the absence of AMF , plants that did not receive P died prematurely. Our study confirmed the hypothesis that BPE increases with increasing nutrient availability, and that carbon partitioning to AMF plays a key role in this nutrient effect. The comparison of inoculated vs. pasteurized mesocosms further suggested a lower carbon cost of nutrient uptake via AMF than via other mechanisms under nutrient rich conditions.