DOI: 10.5061/dryad.s1rn8pkh9
title: Mixedwood conifer trial to compare ectomycorrhizal and arbuscular fungal effects on soil organic matter decay

description: 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
description: 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 Mn<sup>2+</sup> and
 H<sub>2</sub>O<sub>2</sub>. The residual
 peroxidase activity not dependent on Mn as a cofactor was subtracted based
 on reactions in which MnSO<sub>4</sub> was replaced by a
 chelator (2 mM
 Na<sub>2</sub>-EDTA-2H<sub>2</sub>O). Substrate
 controls for background absorption unrelated to enzyme activity were
 supernatants plus reaction solutions without
 H<sub>2</sub>O<sub>2</sub>, 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<sup>-1</sup> g<sup>-1</sup> 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 sequenced on a Sequel II instrument at the Integrated
 Microbiome Resource facility (Halifax, Canada). Fastq files were quality
 filtered and binned into amplicon sequence variants (ASVs) using the DADA2
 software package in R. Taxonomy was assigned using DADA2’s
 assignTaxonomy() function and the UNITE database. Species were further
 assigned to functional guild using FUNguild and published
 literature.
description: # 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. Results are focused on organic matter dynamics via peroxidase activity. Description of the data and file structure Column one is the physical plot number. Column two is the stand type treatment and column three is the density treatment. Column 4 is the subsample for the forest floor properties, while the remaining columns are the data. The main data sets are the forest floor (or organic horizons as the surface) properties under each stand type, including chemistry (C:N ratio and exchangeable Mn), peroxidase activity, ergosterol, organic matter mass and fungal community. **Sharing/Access information** All data used in the manuscript are included in this Dryad submission. Further questions about the data can be made through the British Columbia Ministry of Forests