Fine‐scale diversity and distribution of ectomycorrhizal fungal mycelium in a <scp>S</scp>cots pine forest

<jats:title>Summary</jats:title><jats:p> <jats:list list-type="bullet"> <jats:list-item><jats:p>Ectomycorrhizal (<jats:styled-content style="fixed-case">ECM</jats:styled-content>) mycelium is a key component of the ectomycorrhizal symbiosis, yet we know little regarding the fine‐scale diversity and distribution of mycelium in ECM fungal communities.</jats:p></jats:list-item> <jats:list-item><jats:p>We collected four 20 × 20 × 2‐cm<jats:sup>3</jats:sup> (800‐cm<jats:sup>3</jats:sup>) slices of <jats:styled-content style="fixed-case">S</jats:styled-content>cots pine (<jats:italic><jats:styled-content style="fixed-case">P</jats:styled-content>inus sylvestris</jats:italic>) forest soil and divided each into 100 2 × 2 × 2‐cm<jats:sup>3</jats:sup> (8‐cm<jats:sup>3</jats:sup>) cubes. The presence of mycelium of ECM fungi was determined using an internal transcribed spacer (<jats:styled-content style="fixed-case">ITS</jats:styled-content>) database terminal restriction fragment length polymorphism (<jats:styled-content style="fixed-case">T</jats:styled-content>‐<jats:styled-content style="fixed-case">RFLP</jats:styled-content>) approach.</jats:p></jats:list-item> <jats:list-item><jats:p>As expected, many more ECM fungi were detected as mycelium than as ectomycorrhizas in a cube or slice. More surprisingly, up to one‐quarter of the 43 species previously detected as ectomycorrhizas over an area of 400 m<jats:sup>2</jats:sup> could be detected in a single 8‐cm<jats:sup>3</jats:sup> cube, and up to three‐quarters in a single 800‐cm<jats:sup>3</jats:sup> slice. ECM mycelium frequency decreased markedly with depth and there were distinct ‘hotspots’ of mycelium in the moss/<jats:styled-content style="fixed-case">F</jats:styled-content>1 layer.</jats:p></jats:list-item> <jats:list-item><jats:p>Our data demonstrate a high diversity of <jats:styled-content style="fixed-case">ECM</jats:styled-content> mycelium in a small (8‐cm<jats:sup>3</jats:sup>) volume of substrate, and indicate that the spatial scale at which <jats:styled-content style="fixed-case">ECM</jats:styled-content> species are distributed as mycelium may be very different from the spatial scale at which they are distributed as tips.</jats:p></jats:list-item> </jats:list> </jats:p>