Soil fungi in Swedish woodland
Here we show which fungi are found in Swedish forest soil based on DNA analyzes of fungal mycelium from the uppermost part of the soil, the humus layer. The greatest amount and activity of soil fungi is to be found in this layer.
Analyzes of environmental DNA, eDNA, are good ways to investigate the identity and presence of fungi in soil being present and active in soil all year round. Fungal sporocarps are a temporary, constitute only a small part of the fungi and poorly reflect the total soil fungal community. In addition, many fungi lack visible sporocarps.
Since 2015, the Swedish Forest Soil Inventory (https://www.slu.se/en/markinventeringen), together with The Swedish National Forest Inventory, annually collects humus samples from approx. 350 forests for fungal eDNA analysis.
This investigation gives a good picture of which fungal species are frequent and dominate in different types of Swedish forest. It reveals which species are common and hence important mycorrhizal and decomposer fungi. However, the survey does not capture less frequent and rarer species as it is based on small amounts of soil taken from a relatively small number of forests. The presence of most soil fungi is very local, limited to a few places, perhaps to only a few square meters within in a forest.
The results reported are based on samples from 1,806 forests collected and examined during 2015 – 2019. In these samples, approx. 2,700 different "fungal species" have been identified. Some have been identified to species, others to genus or higher taxonomic rank.
The information on this page is updated as results from more years become complete.
You may examine the occurrence of fungi in two ways
1. Based on species
You can search for a fungal species and get statistics on at how many surveyed forest sites its eDNA has been detected (red dots = sites with presence; unfilled dots = sites where it was not detected) and where the species has been reported as a sporocarps (blue dots) (Sources: Species Observation System and GBIF). Bar charts show in which forest types, at which forest ages and in which types of vegetation the finds were made.
A species or group of species (eg. genus) can be searched for by /p>
- enter the scientific or Swedish name in the box and then click on the name under the table header (if the species has been found) or
- search the Taxonomic Wheel for a group of fungi at different taxonomic levels.
The number of forest sites the species is found in is reported in the table under Plots and on the overview map for Sweden.
2. Based on environmental data
Here you can look up which fungi have been detected and which are most frequent in different types of forests. The results are based on all mushroom findings from the areas covered by the type of forest and where in Sweden you chose to look.
You may choose from and tick from four variables
- northern or southern Sweden, choose one or both
- different forest types
- different average forest ages
- different vegetation types
You may choose one or more forest types, stand ages and types of vegetation.
The Swedish Forest Soil Inventory monitors the state of the soils across all of Sweden except for arable land, urban areas and the high mountains. It is part of the National Environmental Monitoring commissioned by the Swedish Environmental Protection Agency.
The inventory is carried out on permanent inventory plots (314 m2), which are shared with the Swedish National Forest Inventory. The inventory plots are organized in square clusters with a denser sample towards the south of Sweden. Field work is carried out by trained field staff during the summer season. From a smaller subplot (3.14 m2), soil samples are collected from up to five soil layers and in addition, a specific sample for eDNA based analysis of the soil fungal biodiversity. A number of soil chemical properties is also determined from the soil samples (carbon, nitrogen, base cations, aluminum, acidity).
Results from the Swedish Forest Soil Inventory is used to monitor National Environmental Quality Objectives, for reporting of carbon stocks within the LULUCF sector (UNFCCC), among other things. Research, education, and information to society are also important outputs.
Analyzes of fungal communities are based on eDNA extracted from humus samples. The five samples from 3.14 m2 are finely divided and mixed into one collective sample per sampled forest. Molecular species markers are produced using PCR (Polymerase Chain Reaction). We use the most common marker for fungi – ITS2 (Internal Transcribed Spacer 2), which is part of the gene package that codes for the ribosomes in the cells of fungi. The DNA sequences of the ITS2 markers are then read with PacBio SMRT sequencing (Single Molecule, Real-Time sequencing) in collaboration with SciLifeLab NGI in Uppsala (https://www.scilifelab.se/about-us/navet-in-uppsala/).
The species composition in the samples is identified by comparing the sequences in the soil samples with a reference database (UNITE - https://unite.ut.ee/) based on sequences (ITS2) from identified sporocarps and mycelial cultures. Because our species identifications are based on similarities in DNA sequence, our "molecular species" should be considered hypothetical. However, previous studies have found good agreement with biologically/taxonomically defined species. The "molecular species hypotheses" are identified as far as possible - to species and/or genus, or only to higher taxonomic rank if reliable reference data are lacking.
We have chosen to consider a species present in a sample only when it constitutes >1% of the total amount of fungal ITS2 markers in a sample. Because of this occurrence threshold, the number of reported occurrences is lower than the total number of samples in which DNA from a fungal species has been detected. The reasons why we have used this threshold is partly to minimize the risk of occurrences based on fungal spores or contamination during sample preparation, and partly because we have prioritized accurate taxonomic identification (annotation) over automatic identification of a larger number of observations.
The survey has been developed with research funds from Formas, the Swedish Environmental Protection Agency and SLU. Sampling and sequencing are funded on an ongoing basis by the Swedish Environmental Protection Agency. This website has been produced with a grant for SLU's environmental analysis and the Foundation of Anna and Gunnar Vidfelt.
ACCESS TO DATA
The information on this website is mostly based on unpublished data not subject to scientific review yet. As the data is reviewed and published, it will be made openly available via SBDI (https://biodiversitydata.se/) and GBIF (https://www.gbif.org/).