Differences in N-15 uptake amongst spruce seedlings colonized by three pioneer ectomycorrhizal fungi in the field

作者：Jones Melanie D^*; Grenon Frank; Peat Heather; Fitzgerald Michele; Holt Leigh; Philip Leanne J; Bradley Robert

来源：Fungal Ecology, 2009, 2(3): 110-120.

DOI：10.1016/j.funeco.2009.02.002

• Ammonium
• Cenococcum
• Community assemblage
• Dark septate fungi
• Functional diversity
• N-15
• Nitrate
• Nitrogen uptake
• Picea
• Wilcoxina

Amongst the factors hypothesized to be responsible for high ectomycorrhizal fungal diversity are resource partitioning and niche differentiation. However, functional differences amongst ectomycorrhizal fungi, which are pre-requisites for resource partitioning, are known primarily from lab studies; now realistic field experiments are needed in order to establish that these differences exist under field conditions. In this study, Picea engel-mannii seedlings planted in a subalpine clearcut became naturally colonized over the course of 1 y. Then a defined volume of soil around each seedling was injected with N-15-labelled nitrate, ammonium or aspartate. Seedling biomass and N content increased, but N concentration decreased, with percent colonization of root systems. Accumulation of N-15 per unit dry weight was not affected by the proportion of roots colonized but, rather, was influenced by the primary ectomycorrhizal fungus colonizing the seedling. Seedlings colonized by a Wilcoxina sp. accumulated more N-15 per g than seedlings colonized by a Cenococcum sp. The presence of dark septate hyphae in the mantle was associated with lower accumulation of N-15 by seedlings colonized by Amphinema byssoides. Our results demonstrate that the physiological differences required to support the concept of niche differentiation amongst ectomycorrhizal fungi exist in the field.

• 出版日期2009-8