Soil mycobiome informed sustainable nursery production for UK Scots pine afforestation

Concerns are mounting at the increasing loss of economically important native and introduced UK tree species to fungal diseases. Key examples are ash dieback in European ash and red band needle blight in Scots pine from the respective fungal disease causing ascomycetes, Chalara fraxinea and Dothistroma septosporum. Identification of disease resistant genotypes are now being prioritised for future propagation in forest nurseries. Current silvicultural practices involving NPK fertiliser and pesticide application can be counter-productive with regard to the wider environment and ecosystem services.

We report on a three-year pilot project targeting low-input production of Scots pine seedlings in nursery beds amended with factorial combinations of spent compost, bark or the ectomycorrhizal fungus Suillus bovinus. Seedlings grown in un-amended nursery beds and under standard nursery practice served as controls. Improved rooting and weed control in the organic amended treatments after 2 year’s growth highlighted short-term nursery and potential longer-term out-planting benefits in afforestation. Soil samples were taken for genetic analyses from all nursery treatments and a local clear-cut site transplanted with nursery test and control seedlings. DNA extracted from soil was subjected to high-throughput sequencing of a phylogenetically informative rRNA gene sequence (ITS), enabling characterisation of the soil fungal community (mycobiome). Multivariate analyses of the mycobiome highlighted clear community differences between standard practice and organic amendments which were intermediate to clear-cut forest soil previously supporting Corsican pine.

Fungal representation with respect to both beneficial and pathogenic species in the different treatment-specific mycobiomes will be discussed in relation to vegetation development (i.e. target vs. non-target plant communities) and soil edaphic factors. Potential mycorrhizal biocontrol of D. septosporum disease in Scots pine is also being monitored following recent identification of heightened systemic immunity from symbiotic root colonization by related ascomycete species.

Funded by Manchester Metropolitan University and Forestry Commission, Delamere.