Department of Biology, University of Copenhagen, Øster Farimagsgade 2D, 1353 Copenhagen K, Denmark.
Forest & Landscape Denmark, University of Copenhagen, Rolighedsvej 23, 1958 Frederiksberg C, Denmark.
New Phytol. 2012 Apr;194(1):278-286. doi: 10.1111/j.1469-8137.2011.04041.x. Epub 2012 Feb 9.
• 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. • Ectomycorrhizal root tip abundance and mycelial production decreased five and 10-fold, respectively, with increasing N deposition. In addition, the ectomycorrhizal fungal community changed and the species richness decreased. The changes were correlated with the measured indices of N status, in particular N deposition and N leaching. • The relationship between the altered ectomycorrhizal community, root tip abundance and mycelial production is discussed in the context of the N parameters. We suggest that increased N deposition to forests will cause large changes in ectomycorrhizal fungal community structure and functioning, which, in turn, may result in reduced N uptake by roots and fungi, and increased losses of N by leaching.
• 氮（N）供应已知会影响外生菌根真菌的组成部分，如真菌群落组成、根尖生物量和菌丝体的产生，但这些影响从未在同一森林中得到证实。 • 我们同时测量了外生菌根根尖的丰度和外生菌丝体的产生，并在云杉林边缘的一个林分尺度氮沉积梯度（27 至 43 公斤 N ha⁻¹ yr⁻¹）上，探索了外生菌根群落组成的变化。氮状况沿梯度发生变化，表现为一系列氮可用性指数。 • 外生菌根根尖丰度和菌丝体产量分别减少了 5 倍和 10 倍，随着氮沉积的增加而减少。此外，外生菌根真菌群落发生了变化，物种丰富度降低。这些变化与所测量的氮状况指标相关，特别是氮沉积和氮淋溶。 • 我们根据氮参数讨论了改变的外生菌根群落、根尖丰度和菌丝体产量之间的关系。我们认为，森林中增加的氮沉积将导致外生菌根真菌群落结构和功能发生重大变化，这反过来又可能导致根系和真菌对氮的吸收减少，氮淋溶损失增加。
