Carbon-nitrogen relations of ectomycorrhizal mycelium across a natural nitrogen supply gradient in boreal forest.

The supply of carbon (C) from tree photosynthesis to ectomycorrhizal (ECM) fungi is known to decrease with increasing plant nitrogen (N) supply, but how this affects fungal nutrition and growth remains to be clarified. We placed mesh-bags with quartz sand, with or without an organic N ( N-, C-labeled) source, in the soil along a natural N supply gradient in boreal forest, to measure growth and use of N and C by ECM extramatrical mycelia. Mycelial C : N declined with increasing N supply.

Translocation of an arctic seashore plant reveals signs of maladaptation to altered climatic conditions.

Ongoing anthropogenic climate change alters the local climatic conditions to which species may be adapted. Information on species' climatic requirements and their intraspecific variation is necessary for predicting the effects of climate change on biodiversity. We used a climatic gradient to test whether populations of two allopatric varieties of an arctic seashore herb ( ssp.

Dramatic changes in ectomycorrhizal community composition, root tip abundance and mycelial production along a stand-scale nitrogen deposition gradient.

• Nitrogen (N) availability is known to influence ectomycorrhizal fungal components, such as fungal community composition, biomass of root tips and production of mycelia, but effects have never been demonstrated within the same forest. • We measured concurrently the abundance of ectomycorrhizal root tips and the production of external mycelia, and explored the changes in the ectomycorrhizal community composition, across a stand-scale N deposition gradient (from 27 to 43 kg N ha⁻¹ yr⁻¹) at the edge of a spruce forest. The N status was affected along the gradient as shown by a range of N availability indices.

Growth of ectomycorrhizal mycelia and composition of soil microbial communities in oak forest soils along a nitrogen deposition gradient.

Deciduous forests may respond differently from coniferous forests to the anthropogenic deposition of nitrogen (N). Since fungi, especially ectomycorrhizal (EM) fungi, are known to be negatively affected by N deposition, the effects of N deposition on the soil microbial community, total fungal biomass and mycelial growth of EM fungi were studied in oak-dominated deciduous forests along a nitrogen deposition gradient in southern Sweden. In-growth mesh bags were used to estimate the production of mycelia by EM fungi in 19 oak stands in the N deposition gradient, and the results were compared with nitrate leaching data obtained previously.

Limited transfer of nitrogen between wood decomposing and ectomycorrhizal mycelia when studied in the field.

Transfer of (15)N between interacting mycelia of a wood-decomposing fungus (Hypholoma fasciculare) and an ectomycorrhizal fungus (Tomentellopsis submollis) was studied in a mature beech (Fagus sylvatica) forest. The amount of (15)N transferred from the wood decomposer to the ectomycorrhizal fungus was compared to the amount of (15)N released from the wood-decomposing mycelia into the soil solution as (15)N-NH(4). The study was performed in peat-filled plastic containers placed in forest soil in the field.

Growth and biomass of mycorrhizal mycelia in coniferous forests along short natural nutrient gradients.

Total fungal biomass, the biomass of ectomycorrhizal and ericoid mycorrhizal (EM + ErM), and arbuscular mycorrhizal (AM) fungi, as well as the production of EM and AM fungi, were estimated in coniferous forest soils along four natural nutrient gradients. Plant community changes, forest productivity, soil pH and N availability increase over relatively short distances (< 100 m) along the gradients. The amounts of the phospholipid fatty acid (PLFA) 18 : 2omega6,9 were used to estimate total fungi (not including AM), and the PLFA 16 : 1omega5 to estimate AM fungi in soil samples.