Similar below-ground carbon cycling dynamics but contrasting modes of nitrogen cycling between arbuscular mycorrhizal and ectomycorrhizal forests

• Published in: The New phytologist Vol. 213; no. 3; pp. 1440 - 1451
• Main Authors: Lin, Guigang, McCormack, M. Luke, Ma, Chengen, Guo, Dali
• Format: Journal Article
• Language: English
• Published: England New Phytologist Trust 01.02.2017; Wiley Subscription Services, Inc
• Subjects: Biomass; Carbon - metabolism; Carbon Cycle; Forests; Geography; litter quality; Mycorrhizae - metabolism; mycorrhizal association; mycorrhizal type; Nitrogen - metabolism; Nitrogen Cycle; nutrient economy; plant functional group; Plant Leaves - physiology; plant traits; plant–soil interactions; litter quality; plant-soil interactions; nutrient economy; plant functional group; mycorrhizal association; mycorrhizal type; plant traits
• ISSN: 0028-646X; 1469-8137
• DOI: 10.1111/nph.14206

Compared with ectomycorrhizal (ECM) forests, arbuscular mycorrhizal (AM) forests are hypothesized to have higher carbon (C) cycling rates and a more open nitrogen (N) cycle To test this hypothesis, we synthesized 645 observations, including 22 variables related to below-ground C and N dynamics from 100 sites, where AM and ECM forests co-occurred at the same site. Leaf litter quality was lower in ECM than in AM trees, leading to greater forest floor C stocks in ECM forests. By contrast, AM forests had significantly higher mineral soil C concentrations, and this result was strongly mediated by plant traits and climate. No significant differences were found between AM and ECM forests in C fluxes and labile C concentrations. Furthermore, inorganic N concentrations, net N mineralization and nitrification rates were all higher in AM than in ECM forests, indicating ‘mineral’ N economy in AM but ‘organic’ N economy in ECM trees. AM and ECM forests show systematic differences in mineral vs organic N cycling, and thus mycorrhizal type may be useful in predicting how different tree species respond to multiple environmental change factors. By contrast, mycorrhizal type alone cannot reliably predict below-ground C dynamics without considering plant traits and climate.