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Uptake of pulse injected nitrogen by soil microbes and mycorrhizal and non-mycorrhizal plants in a species-diverse subarctic heath ecosystem

Andresen, Louise C.; Jonasson, Sven; Ström, Lena LU and Michelsen, Anders (2008) In Plant and Soil 313(1-2). p.283-295
Abstract
N-15 labeled ammonium, glycine or glutamic acid was injected into subarctic heath soil in situ, with the purpose of investigating how the nitrogen added in these pulses was subsequently utilized and cycled in the ecosystem. We analyzed the acquisition of N-15 label in mycorrhizal and non-mycorrhizal plants and in soil microorganisms, in order to reveal probable differences in acquisition patterns between the two functional plant types and between plants and soil microorganisms. Three weeks after the label addition, with the N-15-forms added with same amount of nitrogen per square meter, we analyzed the N-15-enrichment in total soil, in soil K2SO4 (0.5 M) extracts and in the microbial biomass after vacuum-incubation of soil in chloroform... (More)
N-15 labeled ammonium, glycine or glutamic acid was injected into subarctic heath soil in situ, with the purpose of investigating how the nitrogen added in these pulses was subsequently utilized and cycled in the ecosystem. We analyzed the acquisition of N-15 label in mycorrhizal and non-mycorrhizal plants and in soil microorganisms, in order to reveal probable differences in acquisition patterns between the two functional plant types and between plants and soil microorganisms. Three weeks after the label addition, with the N-15-forms added with same amount of nitrogen per square meter, we analyzed the N-15-enrichment in total soil, in soil K2SO4 (0.5 M) extracts and in the microbial biomass after vacuum-incubation of soil in chloroform and subsequent K2SO4 extraction. Furthermore the N-15-enrichment was analyzed in current years leaves of the dominant plant species sampled three, five and 21 days after label addition. The soil microorganisms had very high N-15 recovery from all the N sources compared to plants. Microorganisms incorporated most N-15 from the glutamic acid source, intermediate amounts of N-15 from the glycine source and least N-15 from the NH4+ source. In contrast to microorganisms, all ten investigated plant species generally acquired more N-15 label from the NH4+ source than from the amino acid sources. Non-mycorrhizal plant species showed higher concentration of N-15 label than mycorrhizal plant species 3 days after labeling, while 21 days after labeling their acquisition of N-15 label from amino acid injection was lower than, and the acquisition of N-15 label from NH4 injection was similar to that of the mycorrhizal species. We conclude that the soil microorganisms were more efficient than plants in acquiring pulses of nutrients which, under natural conditions, occur after e. g. freeze-thaw and dry rewet events, although of smaller size. It also appears that the mycorrhizal plants in the short term may be less efficient than non-mycorrhizal plants in nitrogen acquisition, but in a longer term show larger nitrogen acquisition than non-mycorrhizal plants. However, the differences in N-15 uptake patterns may also be due to differences in leaf longevity and woodiness between plant functional groups. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
nitrogen, Organic, N-15, Mycorrhiza, Freeze-thaw cycle, Ammonium, Amino acid, Plant nitrogen uptake, Root biomass
in
Plant and Soil
volume
313
issue
1-2
pages
283 - 295
publisher
Springer
external identifiers
  • wos:000260961600022
  • scopus:56349106865
ISSN
0032-079X
DOI
10.1007/s11104-008-9700-7
language
English
LU publication?
yes
id
d51d1ca8-cb4c-423a-aa56-29ef0b69f069 (old id 1305867)
date added to LUP
2009-03-20 11:12:21
date last changed
2017-11-05 04:15:13
@article{d51d1ca8-cb4c-423a-aa56-29ef0b69f069,
  abstract     = {N-15 labeled ammonium, glycine or glutamic acid was injected into subarctic heath soil in situ, with the purpose of investigating how the nitrogen added in these pulses was subsequently utilized and cycled in the ecosystem. We analyzed the acquisition of N-15 label in mycorrhizal and non-mycorrhizal plants and in soil microorganisms, in order to reveal probable differences in acquisition patterns between the two functional plant types and between plants and soil microorganisms. Three weeks after the label addition, with the N-15-forms added with same amount of nitrogen per square meter, we analyzed the N-15-enrichment in total soil, in soil K2SO4 (0.5 M) extracts and in the microbial biomass after vacuum-incubation of soil in chloroform and subsequent K2SO4 extraction. Furthermore the N-15-enrichment was analyzed in current years leaves of the dominant plant species sampled three, five and 21 days after label addition. The soil microorganisms had very high N-15 recovery from all the N sources compared to plants. Microorganisms incorporated most N-15 from the glutamic acid source, intermediate amounts of N-15 from the glycine source and least N-15 from the NH4+ source. In contrast to microorganisms, all ten investigated plant species generally acquired more N-15 label from the NH4+ source than from the amino acid sources. Non-mycorrhizal plant species showed higher concentration of N-15 label than mycorrhizal plant species 3 days after labeling, while 21 days after labeling their acquisition of N-15 label from amino acid injection was lower than, and the acquisition of N-15 label from NH4 injection was similar to that of the mycorrhizal species. We conclude that the soil microorganisms were more efficient than plants in acquiring pulses of nutrients which, under natural conditions, occur after e. g. freeze-thaw and dry rewet events, although of smaller size. It also appears that the mycorrhizal plants in the short term may be less efficient than non-mycorrhizal plants in nitrogen acquisition, but in a longer term show larger nitrogen acquisition than non-mycorrhizal plants. However, the differences in N-15 uptake patterns may also be due to differences in leaf longevity and woodiness between plant functional groups.},
  author       = {Andresen, Louise C. and Jonasson, Sven and Ström, Lena and Michelsen, Anders},
  issn         = {0032-079X},
  keyword      = {nitrogen,Organic,N-15,Mycorrhiza,Freeze-thaw cycle,Ammonium,Amino acid,Plant nitrogen uptake,Root biomass},
  language     = {eng},
  number       = {1-2},
  pages        = {283--295},
  publisher    = {Springer},
  series       = {Plant and Soil},
  title        = {Uptake of pulse injected nitrogen by soil microbes and mycorrhizal and non-mycorrhizal plants in a species-diverse subarctic heath ecosystem},
  url          = {http://dx.doi.org/10.1007/s11104-008-9700-7},
  volume       = {313},
  year         = {2008},
}