Mineral nutrition and mycorrhizal infection of seedling oak and birch

Abstract

summaryIn order to determine the effect of fertilizers on the growth, nutrient uptake and ectomycorrhizal infection of seedling oak (Quercus robur L.) and birch (Betula. pendula Roth.), N, P and K fertilizers were applied in a factorial design to plots of seedlings artificially established ph two woodland sites on nutrient‐poor soils. A parallel series of pot experiments were undertaken using the sajne design, in order to eliminate the effects of neighbouring mature trees on growth and mineral uptake.Fertilizer addition increased the growth of birch in both pot and field experiments, and on both soil types, by up to 39 %. In contrast, fertilizer addition had little effect on growth of oak, other than to increase dry mass by 11 % in one of the pot experiments. Application of N, P and K generally increased the foliar concentration of the respective nutrient, by up to 49%. However, a number of negative effects of fertilizer application were recorded, particularly in the case of foliar P. For example, application of N K and N × K reduced the foliar P of birch by up to 35 % in pots.Fertilizer application to both species tended to reduce ectoniycrrhizal infection, both in pots and in the field. These effects were more pronounced for birch than oak, and a greater number of effects were recorded in pots than in the field. In general, N had the greatest effect. For example, the number of mycorrhizal tips of birch in pots was reduced to 38 % of the control value, following N application. Application of P and K also reduced mycorrhizal infection, although the results of the analyses differed depending on how mycorrhizal infection was assessed.The relative proportions of a number of the ectomycorrhizal types were also influenced by fertilizer addition. Although the proportion of most types was reduced, two types [formed by Paxillus involutus (Batsch) Fr. and Scleroderma citrinum Pers.] increased in some of the treatments where they were dominant. For example, application of N to birch in pots increased the proportion of P. involutus mycorrhizas to 172% of the control.The interactions between the effect of fertilizers on growth, nutrient uptake and mycorrhizal infection are discussed, and some implications for forest management are highlighted.