INSTYTUT DENDROLOGII

Diversity of mycorrhizas of 12 forest tree species growing in monoculture plots

The aim of the present work was to identify the ectomycorrhizal fungi (EMF) of 12 forest tree species (Abies alba, Betula pendula, Carpinus betulus, Fagus sylvatica, Larix decidua, Picea abies, Pinus nigra, Pinus sylvestris, Pseudotsuga menziesii, Quercus robur, Quercus rubra, and Tilia cordata) growing in monoculture plots and to compare the ectomycorrhizal community structures among studied trees. It was hypothesized that each tree species had developed unique ectomycorrhizal community structure. However, closely related tree species (of the same family or genus) would have more similar ectomycorrhizal community structure. It was also assumed that forest site (conifer and mixed) would have influence on EMF community structure and higher richness of EMF would be on the conifer forest site (this hypothesis was established for 4 tree species growing on boh forest sites: Picea abies, Larix decidua, Pseudotsuga menziesii, and Quercus robur).

Identification of ectomycorrhizal fungus was based preliminary morphological studies of ectomycorrhizas and ITS sequencing of fungal symbiont.

In total 70 different morphological ectomycorrhizal types was evaluated which consisted of 58 fungal species. Fourty nine belonged to Basidiomycota and 9 belonged to Ascomycota. The most common EMF species was Cenococcum geophilum that was found on all 12 tree species. Another common EMF species was Paxillus involutus that was not observed only on Tilia cordata. The most richness fungal families were Thelephoraceae (represented by 16 EMF species) and Russulaceae (represented by 8 EMF species).

Studied tree species had statistically different number of EMF species: the highest number of EMF was on Fagus sylvatica (17), Betula pendula (16), and Quercus robur (16), whereas the lowest number of EMF species was on Larix decidua (7), Abies alba (8), and Picea abies (9). Ectomycorrhizal community structure was different on studied tree species:

a) tree of Pinaceae had the most similar EMF community structure-among themthe highest Jaccard index was found for Picea abies-Pinus sylvestris (72,7%), Pseudotsuga menziesii-Larix decidua (70,6%), Picea abies-Pinus nigra (63%), and Pinus nigra-Pinus sylvestris (61%),

b) among tree of Betulaceae and Fagaceae the highest Jacard index was for Carpinus betulus-Quercus robur (61,6%) and for Quercus rubra-Quercus robur (54%); the lowest was for Fagus sylvatica-Quercus rubra (29,6%). The EMF community structure was more variable for Betulaceae and Fagaceae in comparison with Pinaceae: Betula pendula, Quercus robur and Fagus sylvatica characterized the most variable EMF community strucures,

c) the most different EMF community structure among 12 studed tree species had Tilia cordata (Tiliaceae),

d) similarity of EMF community structures was not always related with taxonomic relationship of trees i.e.: higher Jaccard index was for Quercus rubra-Carpinus betulus than for Q. rubra-Q. robur,

e) exotic and native tree species (that belonged to the same genus: Pinus and Quercus) shared many EMF species, although EMF richness was higher for native tree species than for exotic ones.

Four trees (Larix decidua, Picea abies, Pseudotsuga menziesii, and Quercus robur) growing on both forest sites (conifer and mixed) had significantly different number of EMF: higher number of EMF was on Picea abies, Pseudotsuga menziesii, and Quercus robur growing on conifer forest site. However, correspondence analysis and clustering analysis showed no effect of forest site on EMF community structure among 4 tree species.

Identification of ectomycorrhizal fungus based on molecular techniques is a great tool. However, in the event of DNA amplification of many fungi occured in an individual ectomycorrhizal root tip this approach is not sufficient. In that case, a detailed morphological study of ectomycorrhizas combided with molecular approach is highly needed for accurate EMF identification.