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Dryad

Mixedwood conifer trial to compare ectomycorrhizal and arbuscular fungal effects on soil organic matter decay

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Dec 12, 2024 version files 104.90 KB

Abstract

The purportedly enhanced decay of soil organic matter (SOM) by ectomycorrhizal fungi (EMF), in contrast to arbuscular mycorrhiza (AMF), was tested in a 30-year old mixedwood trial. Total peroxidase activity, including manganese-peroxidase (MnP), and mass of the humus layer were compared between Pseudotsuga menziesii (EMF) and Thuja plicata (AMF) across a natural productivity gradient. We found total peroxidase and MnP activity diverged between hosts as humus C:N increased, culminating in 3- to 4-fold greater enzyme activity for EMF on low fertility soils. This edaphic effect also correlated significantly with exchangeable Mn, highlighting a possible further restriction on SOM turnover by EMF. Peroxidase activity was well aligned with EMF species other than Cortinariaceae, notably Piloderma olivaceum and Piloderma sphaerosporum. The 3-fold decline in humus mass with decreasing soil fertility under P. menziesii, unlike T. plicata, was strong affirmation that EMF engaged in organic N liberation can lead to reductions in SOMcarbon sequestration