INSTYTUT DENDROLOGII

Ectomycorhizal community composition of oaks on Krotoszyńskie Forests area

Pedunculate oak (Quercus robur L.) and sessile oak (Q. petraea (Matt.) Liebl.) are a widespread species of ecological and economic importance in Europe. Both are obligatorily associated with ectomycorrhizal fungi (EMF). Until now several papers describing ECM communities of pedunculate and others oak species in different ecosystems and site conditions has been published, but none of the previous studies has focused on comprehensive description of EMF communities from one distinctive region. Therefore the aim of this study was to present extensive data describing the fungal species richness and composition of oak seedlings growing in bare-root forest nurseries, trees along a chronosequence of stands and in the various declining tree stage.

Study sites were located in Krotoszyńskie Forests considered as the largest oak forests in Poland. Altogether 460 soil samples were taken from 15 study sites and nursery. Morphological assessment and molecular approach based on PCR and sequencing of the fungal ITS rDNA were performed to identify fungal partner of ectomycorrhizas.

Altogether 97 EMF taxa associated with oaks have been recorded.

In nursery experiment altogether 9 EMF taxa has been recorded during the first year of seedlings growth. First mycorrhizas of Scleroderma verrucosum were observed 50 days after acorns outplanting. Nursery experiment also shown that leave infection by pathogenic fungus, Erysiphe alphitoides strongly reduce number of living ectomycorrhizas.

Chronosequence study revealed high diversity of EMF (75 taxa) and has shown correlation between relative abundance of some group of fungi and age of the trees. Cadophora/Rhisoscyphus/Meliniomycetes group was strongly connected with youngest (regeneration) stage of stand development. On the other hand number of Russula spp. increased with stand age from one taxon in regeneration stage to nine species in mature tree stage. The most common fungus was Cenococcum geophilum aggregate with relative abundance ranging 7.11% to 53.01%.

In declining stands 37 EMF taxa were identified. Lowest number of EMF species richness and highest abundance of L. quietus were noted for oak stands with high average defoliation level. My study clearly shown that health status of trees affect EMF community composition and richness, especially regarding stand-level estimation.

This study significantly increased our knowledge about ECM fungal symbionts accompanying pedunculate and sessile oak trees. Thelephoroid (17taxa) and russuloid fungi (14 taxa) has been found as the most common group of oak symbionts,. Three EMF taxa (Tomentella castanea, T. italica, T. liliosingrisea) has been noted for the first time in Poland.