Uptake of pulse injected nitrogen by soil microbes and mycorrhizal and non-mycorrhizal plants in a species-diverse subarctic heath ecosystem
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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 Christoffersen; Jonasson, Sven; Strom, Lena; Michelsen, Anders.
I: Plant and Soil, Bind 313, Nr. 1-2, 2008, s. 283-295.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
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TY - JOUR
T1 - Uptake of pulse injected nitrogen by soil microbes and mycorrhizal and non-mycorrhizal plants in a species-diverse subarctic heath ecosystem
AU - Andresen, Louise Christoffersen
AU - Jonasson, Sven
AU - Strom, Lena
AU - Michelsen, Anders
N1 - Keywords Ammonium - Amino acid - Freeze-thaw cycle - Mycorrhiza - 15N - Organic nitrogen - Plant nitrogen uptake - Root biomass
PY - 2008
Y1 - 2008
N2 - 15N 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 15N 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 15N-forms added with same amount of nitrogen per square meter, we analyzed the 15N-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 15N-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 15N recovery from all the N sources compared to plants. Microorganisms incorporated most 15N from the glutamic acid source, intermediate amounts of 15N from the glycine source and least 15N from the NH4 + source. In contrast to microorganisms, all ten investigated plant species generally acquired more 15N label from the NH4 + source than from the amino acid sources. Non-mycorrhizal plant species showed higher concentration of 15N label than mycorrhizal plant species 3 days after labeling, while 21 days after labeling their acquisition of 15N label from amino acid injection was lower than, and the acquisition of 15N 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 15N uptake patterns may also be due to differences in leaf longevity and woodiness between plant functional groups.
AB - 15N 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 15N 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 15N-forms added with same amount of nitrogen per square meter, we analyzed the 15N-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 15N-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 15N recovery from all the N sources compared to plants. Microorganisms incorporated most 15N from the glutamic acid source, intermediate amounts of 15N from the glycine source and least 15N from the NH4 + source. In contrast to microorganisms, all ten investigated plant species generally acquired more 15N label from the NH4 + source than from the amino acid sources. Non-mycorrhizal plant species showed higher concentration of 15N label than mycorrhizal plant species 3 days after labeling, while 21 days after labeling their acquisition of 15N label from amino acid injection was lower than, and the acquisition of 15N 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 15N uptake patterns may also be due to differences in leaf longevity and woodiness between plant functional groups.
KW - Faculty of Science
KW - økologi
KW - planter
KW - jord
KW - arktis
KW - ecology
KW - plants
KW - soil
KW - arctic
U2 - 10.1007/s11104-008-9700-7
DO - 10.1007/s11104-008-9700-7
M3 - Journal article
VL - 313
SP - 283
EP - 295
JO - Plant and Soil
JF - Plant and Soil
SN - 0032-079X
IS - 1-2
ER -
ID: 8379100