1. Recovery of ectomycorrhiza after 'nitrogen saturation' of a conifer forest.
- Author
-
Högberg P, Johannisson C, Yarwood S, Callesen I, Näsholm T, Myrold DD, and Högberg MN
- Subjects
- Carbon metabolism, Nitrogen metabolism, Nitrogen Isotopes, Plant Leaves drug effects, Plant Leaves metabolism, Plant Leaves microbiology, Soil chemistry, Soil Microbiology, Sweden, Mycorrhizae drug effects, Mycorrhizae physiology, Nitrogen pharmacology, Pinus sylvestris drug effects, Pinus sylvestris microbiology, Trees drug effects, Trees microbiology
- Abstract
Trees reduce their carbon (C) allocation to roots and mycorrhizal fungi in response to high nitrogen (N) additions, which should reduce the N retention capacity of forests. The time needed for recovery of mycorrhizas after termination of N loading remains unknown. Here, we report the long-term impact of N loading and the recovery of ectomycorrhiza after high N loading on a Pinus sylvestris forest. We analysed the N% and abundance of the stable isotope (15) N in tree needles and soil, soil microbial fatty acid biomarkers and fungal DNA. Needles in N-loaded plots became enriched in (15) N, reflecting decreased N retention by mycorrhizal fungi and isotopic discrimination against (15) N during loss of N. Meanwhile, needles in N-limited (control) plots became depleted in (15) N, reflecting high retention of (15) N by mycorrhizal fungi. N loading was terminated after 20yr. The δ(15) N and N% of the needles decreased 6yr after N loading had been terminated, and approached values in control plots after 15yr. This decrease, and the larger contributions compared with N-loaded plots of a fungal fatty acid biomarker and ectomycorrhizal sequences, suggest recovery of ectomycorrhiza. High N loading rapidly decreased the functional role of ectomycorrhiza in the forest N cycle, but significant recovery occurred within 6-15yr after termination of N loading., (© The Authors (2010). Journal compilation © New Phytologist Trust (2010).)
- Published
- 2011
- Full Text
- View/download PDF