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Contrasting effects of low and high nitrogen additions on soil CO2 flux components and ectomycorrhizal fungal sporocarp production in a boreal forest

Hasselquist, Niles J.; Metcalfe, Dan LU and Hogberg, Peter (2012) In Global Change Biology 18(12). p.3596-3605
Abstract
Nitrogen (N) added through atmospheric deposition or as fertilizer to boreal and temperate forests reduces both soil decomposer activity (heterotrophic respiration) and the activity of roots and mycorrhizal fungi (autotrophic respiration). However, these negative effects have been found in studies that applied relatively high levels of N, whereas the responses to ambient atmospheric N deposition rates are still not clear. Here, we compared an unfertilized control boreal forest with a fertilized forest (100 kg N ha(-1) yr(-1)) and a forest subject to N-deposition rates comparable to those in Central Europe (20 kg N ha(-1) yr(-1)) to investigate the effects of N addition rate on different components of forest floor respiration and the... (More)
Nitrogen (N) added through atmospheric deposition or as fertilizer to boreal and temperate forests reduces both soil decomposer activity (heterotrophic respiration) and the activity of roots and mycorrhizal fungi (autotrophic respiration). However, these negative effects have been found in studies that applied relatively high levels of N, whereas the responses to ambient atmospheric N deposition rates are still not clear. Here, we compared an unfertilized control boreal forest with a fertilized forest (100 kg N ha(-1) yr(-1)) and a forest subject to N-deposition rates comparable to those in Central Europe (20 kg N ha(-1) yr(-1)) to investigate the effects of N addition rate on different components of forest floor respiration and the production of ectomycorrhizal fungal sporocarps. Soil collars were used to partition heterotrophic (R-h) and autotrophic (R-a) respiration, which was further separated into respiration by tree roots (R-tr) and mycorrhizal hyphae (R-m). Total forest floor respiration was twice as high in the low N plot compared to the control, whereas there were no differences between the control and high N plot. There were no differences in R-h respiration among plots. The enhanced forest floor respiration in the low N plot was, therefore, the result of increased R-a respiration, with an increase in R-tr respiration, and a doubling of R-m respiration. The latter was corroborated by a slightly greater ectomycorrhizal (EM) fungal sporocarp production in the low N plot as compared to the control plot. In contrast, EM fungal sporocarp production was nearly eliminated, and R-m respiration severely reduced, in the high N plot, which resulted in significantly lower R-a respiration. We thus found a nonlinear response of the R-a components to N addition rate, which calls for further studies of the quantitative relations among N addition rate, plant photosynthesis and carbon allocation, and the function of EM fungi. (Less)
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author
publishing date
type
Contribution to journal
publication status
published
subject
keywords
autotrophic respiration, carbon flux, forest soil, mycorrhiza, nitrogen, deposition, Scots pine, soil respiration partitioning
in
Global Change Biology
volume
18
issue
12
pages
3596 - 3605
publisher
Wiley-Blackwell
external identifiers
  • wos:000310564200011
  • scopus:84868211781
ISSN
1354-1013
DOI
10.1111/gcb.12001
language
English
LU publication?
no
id
19cc5078-4053-47cf-9d2b-194205d68484 (old id 4643896)
date added to LUP
2014-09-26 07:51:47
date last changed
2017-10-01 03:26:31
@article{19cc5078-4053-47cf-9d2b-194205d68484,
  abstract     = {Nitrogen (N) added through atmospheric deposition or as fertilizer to boreal and temperate forests reduces both soil decomposer activity (heterotrophic respiration) and the activity of roots and mycorrhizal fungi (autotrophic respiration). However, these negative effects have been found in studies that applied relatively high levels of N, whereas the responses to ambient atmospheric N deposition rates are still not clear. Here, we compared an unfertilized control boreal forest with a fertilized forest (100 kg N ha(-1) yr(-1)) and a forest subject to N-deposition rates comparable to those in Central Europe (20 kg N ha(-1) yr(-1)) to investigate the effects of N addition rate on different components of forest floor respiration and the production of ectomycorrhizal fungal sporocarps. Soil collars were used to partition heterotrophic (R-h) and autotrophic (R-a) respiration, which was further separated into respiration by tree roots (R-tr) and mycorrhizal hyphae (R-m). Total forest floor respiration was twice as high in the low N plot compared to the control, whereas there were no differences between the control and high N plot. There were no differences in R-h respiration among plots. The enhanced forest floor respiration in the low N plot was, therefore, the result of increased R-a respiration, with an increase in R-tr respiration, and a doubling of R-m respiration. The latter was corroborated by a slightly greater ectomycorrhizal (EM) fungal sporocarp production in the low N plot as compared to the control plot. In contrast, EM fungal sporocarp production was nearly eliminated, and R-m respiration severely reduced, in the high N plot, which resulted in significantly lower R-a respiration. We thus found a nonlinear response of the R-a components to N addition rate, which calls for further studies of the quantitative relations among N addition rate, plant photosynthesis and carbon allocation, and the function of EM fungi.},
  author       = {Hasselquist, Niles J. and Metcalfe, Dan and Hogberg, Peter},
  issn         = {1354-1013},
  keyword      = {autotrophic respiration,carbon flux,forest soil,mycorrhiza,nitrogen,deposition,Scots pine,soil respiration partitioning},
  language     = {eng},
  number       = {12},
  pages        = {3596--3605},
  publisher    = {Wiley-Blackwell},
  series       = {Global Change Biology},
  title        = {Contrasting effects of low and high nitrogen additions on soil CO2 flux components and ectomycorrhizal fungal sporocarp production in a boreal forest},
  url          = {http://dx.doi.org/10.1111/gcb.12001},
  volume       = {18},
  year         = {2012},
}