Background and aims Arbuscular (AM) and ectomycorrhizas (EM) predominate in different soils.We hypothesise that also climatic factors affect directly their relative success and AM fungi (AMF) generally tolerate drought better than EM fungi (EMF). Here we tested the colonisation rates of soil-borne AMF and EMF after soil drought treatments.Methods Forest and meadow soils were mixed to include AMF and EMF propagules. There were three soil treatments: soil moisture corresponding to 60% (control) or 10% in mass of maximum water retention, or air-dry. The bait plants were EM-forming silver birch (Betula pendula), dualmycorrhiza forming grey alder (Alnus incana) and AM-forming white clover (Trifolium repens).After re-watering, bait plants were sown and grown in a growth chamber in favourable conditions. This way, host-plant responses to drought were eliminated.Results Previous soil drought decreased EM colonisation in alder. The spore formation by AMF in clover was negatively affected after the most severe soil drought treatment, suggesting slightly retarded AM formation. Soluble soil potassium concentrations were lower in drought-treated soils and this was reflected in birch foliar concentrations. ConclusionsThe results provide some support to the hypothesised better drought tolerance of AMF than EMF propagules but further studies in milder drought and in other plant-fungus combinations are needed.

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Background and aims The aim was to assess possible benefits or drawbacks of arbuscular-mycorrhizal (AM) and ectomycorrhizal (EM) colonisation compared to no mycorrhizas (NM) in seedlings of the same host species. Eight broadleaf species were tested for mycorrhiza formation. Grey alder (Alnus incana) and four fungal species were selected for further experiments. Methods Grey alder seedlings were inoculated with AM fungi Rhizophagus intraradices and Glomus hoi or EM fungi Paxillus involutus plus an ascomycete isolated from Alnus roots or mock-inoculated (NM). Results EM formed in 70% of root tips and AM in 30% of root length. AM plants were smaller than EM and NM, but their specific root length (SRL) and specific leaf area (SLA) were highest. Net photosynthesis, stomatal conductance and shoot water potential did not differ between treatments. Foliar Ca, K, Mg, Mn, N, P and S concentrations (mg g −1) were highest in AM plants. However, total foliar contents (mg per plant) were lowest in AM plants, except for P, K and Zn. Conclusions The larger SRL and SLA suggest more efficient resource usage in AM plants, even though these were smaller than EM and NM plants. Grey alder is proposed as a new model species for comparisons between mycorrhiza types in cold climates.

The quest for cleaner wood preservatives is one of the major foci of contemporary wood science. Pyrolysis distillates are potential intermediates to extract large volumes of bioactive chemicals. The aim of this study was to characterize pyrolysis distillates from spruce and birch bark and hemp and test different fractions as potential antifungals to prevent wood decay. In all the fungi tested, distillates of spruce caused over 40% inhibition at 0.1% concentration; 19 significant inhibition could be observed when the concentration of the distillates in growth 20 media was 1%. The results indicate that inhibition was caused by the synergetic action of 21 different chemicals in the pyrolysis distillates. When the individual components were 22 considered, propionic acid exhibited a very high inhibitory effect against the wood decay fungi. 23 2 The high inhibition of the pyrolysis distillates at 1% and lower concentrations demonstrate that pyrolysis liquids could be a source for formulations of sustainable wood preservatives.