INSTYTUT DENDROLOGII

The communities of ectomycorrhizas of Norway spruce and soil microorganisms in mature forests

The communities of ectomycorrhizas and soil microorganisms were studied in four mature, ecologically different forests stands in Poland. Three of the forests (Brenna, Salmopol, Zwierzyniec) were located within the natural geographical range of Norway spruce and one (Mirachowo) was located in so-called "spruce-less zone". The forests differed in the species composition and the level of air and soil contamination by toxic compounds. The aim of this research was to study the relations between ecological conditions and the diversity of ectomycorrhizal communities of Norway spruce (Picea abies (L.) Karst.), the biomass of ectomycorrhizal mycelium in mycorrhizosphere, the community structure and biomass of soil microorganisms in Norway spruce forests.

Ectomycorrhizas were characterised on the basis of their macroscopic and microscopic
features, by use of whole cell fatty acid (WCFA) profiles and molecular analyses of DNA. Extramatrical mycelium of mycorrhizal fungi was isolated from soil using mesh bags method and fungal biomass was estimated on the basis of ergosterol content. The structure and biomass of microbial communities were described by the content of phospholipid fatty acids in a soil. The biomass of soil fungi was estimated on the basis of the fungal specific fatty acid (linoleic fatty acid) and ergosterol contetnt in soil. The whole-cell fatty acid profile of ectomycorrhizal fungi (sporocarps and cultures in vitro) were also analysed.

Biodiversity of ectomycorrhizal communities and biomass of ectomycorrhizal mycelium indicated that the forest stands studied were in similar condition as some other European forests, not influenced by any strong and direct stresses and in a better condition than some forests influenced by natural stresses (e.g. severe climate in northern Scandinavia) or anthropogenic stresses (e.g. heavy metal and nitrogen pollution of soil in Slovenia and Southern Scandinavia).

The results indicated differences between the four forest sites studied in the abundance, composition of ectomycorrhizal fungi and Norway spruce ectomycorrhizas, biomass of ectomycorrhizal mycelium and that mycorrhiza of a spruce was influenced mainly by the local environmental conditions. Taxonomic groups of ectomycorrhizal fungi reveal specific fatty acid profiles. A strong relationship betweeen ectomycorrhizal fungi and soil microorganisms, indicated by analogous biomass changes of both organism groups in soil during the growth season and by the presence of specific bacterial fatty acids in different structures of ectomycorrhizal fungi was found. It was concluded that biochemical analyses can be used as fast methods in quantification of mycorrhizas and soil microorganisms in forests.