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

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 liber..., The assay method for total and Mn-dependent peroxidase activity was based on oxidative coupling of DMAB (3-dimethylaminobenzoic acid) and MBTH (3-methyl-2-benzothiazolinone hydrazone hydrochloride) in the presence of Mn2+ and H2O2. The residual peroxidase activity not dependent on Mn as a cofactor was subtracted based on reactions in which MnSO4 was replaced by a chelator (2 mM Na2-EDTA-2H2O). Substrate controls for background absorption unrelated to enzyme activity were supernatants plus reaction solutions without H2O2, while boiled samples were used as negative controls to confirm enzyme involvement in the colour change. We assayed 2 subsamples per composite for peroxidase activity (= 6 readings per plot). Enzyme activity was expressed as μmol h-1 g-1 dry soil.
Humus samples were freeze-dried and ground with a ring mill before DNA extraction. Briefly, the full length ITS region was amplified in duplicate from template DNA using high-fidelity Phusion polymerase and fusion primers and s..., , # Mixedwood conifer trial to compare ectomycorrhizal and arbuscular fungal effects on soil organic matter decay

[https://doi.org/10.5061/dryad.s1rn8pkh9](https://doi.org/10.5061/dryad.s1rn8pkh9)

## Description of the data and file structure

### Files and variables

#### File: humus\_layer\_Agaricomycete\_community.xlsx

**Description:** Agaricomycete fungal community

##### Variables

* fungal species by read depth for each plot

#### File: humus\_layer\_properties.xlsx

**Description:** Humus layer properties

##### Variables

* C;N ratio, exchangeable Mn, pH, peroxidase activity and ergosterol

#### File: humus\_layer\_mass.xlsx

**Description:** Humus layer mass

##### Variables

* organic matter mass

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

Included are the humus layer properties and mass data, along with Agaricomycete fungal communities, for a mixed wood trial with western redcedar and coastal Douglas-fir. Re...