Kļaviņa, D.*, Muižnieks, I., Gaitnieks, T., Nikolajeva, V., Lazdiņa, D., Lazdiņš, A., Bārdule, A. and Menkis, A. 2016. Fungal Communities in Roots of Scots Pine and Norway Spruce Saplings Grown for 10 Years on Peat Soils Fertilized with Wood Ash. Baltic F

   The study was conducted in Scots pine (Pinus sylvestris L.) or Norway spruce (Picea abies (L.) H. Karst.) plots on peat soils, where fertilization trials with 0.5 to 2 kg m-2 wood ash had been conducted ten years previously. We examined the long-term effects of wood ash fertilization on fine root development (biomass and mycorrhizal colonization) and on communities of ectomycorrhizal (ECM) fungi and other soil microorganisms. Soil microorganisms were assessed by recording the number of colony forming units (CFU) from soil dilution series. ECM fungi in fine roots were evaluated by morphotyping and identified by sequencing of the fungal ITS region of rRNA genes. Soil chemical analysis indicated significant differences in soil pH between control and fertilized Scots pine plots, but soil pH did not differ among Norway spruce plots. Fine root biomass, numbers of living fine roots and numbers of dead fine roots did not differ significantly among wood ash treatments and the control for either pine or spruce. Relative abundance of living fine roots and its mycorrhizal colonization differed significantly among treatments and effects of wood ash were largely determined by tree species and amount of wood ash applied. Numbers of bacterial CFUs were higher in pine plots than in spruce plots and some differences were evident between the wood ash treatments and the control. Numbers of fungal CFUs were similar in all treatments. Of 21 fungal species identified on fine roots, the most common were Amphinema byssoides, Agaricomycetes sp., Lactarius sp. and Tuber anniae. Species composition of ECM fungi was mainly determined by the host species. However, principal component analysis and comparison of relative abundances of some species indicated differences in species composition among wood ash treatments. In conclusion, our data provided some evidence of a long-term effect of wood ash fertilization on soil pH, abundance of soil bacteria and diversity of ECM fungal community.

Keywords: forest fertilization; liming; organic soils; fine root; ectomycorrhizal fungi, Pinus sylvestris, Picea abies.