Plant and microbial uptake and allocation of organic and inorganic nitrogen related to plant growth forms and soil conditions at two subarctic tundra sites in Sweden

TY - JOUR

T1 - Plant and microbial uptake and allocation of organic and inorganic nitrogen related to plant growth forms and soil conditions at two subarctic tundra sites in Sweden

AU - Sørensen, Pernille Lærkedal

AU - Clemmensen, Karina Engelbrecht

AU - Michelsen, Anders

AU - Jonasson, Sven Evert

AU - Ström, Lena

PY - 2008

Y1 - 2008

N2 - In order to follow the uptake and allocation of N in different plant functional types andmicrobes in two tundra ecosystems differing in nutrient availability, we performed a 15Nlabelingexperiment with three N forms and followed the partitioning of 15N labelamong plants, microorganisms and soil organic matter. At both sites the deciduousdwarf shrub Betula nana and the evergreen Empetrum hermaphroditum absorbed added15N at rates in the order: NH4+ . NO32 . glycine, in contrast to the graminoid Carexspecies which took up added 15N at rates in the orderNO32 . NH4+ . glycine. Carextransported a high proportion of 15N to aboveground parts, whereas the dwarf shrubsallocated most 15N to underground storage. Enhanced 13C in Betula nana rootsrepresents the first field evidence of uptake of intact glycine by this importantcircumpolar plant. Plant and microbial uptake of label was complementary as plantstook up more inorganic than organic N, while microbes preferred organic N. Microbesinitially took up a large part of the added label, but over the following four weeksmicrobial 15N decreased by 50% and most 15N was recovered in soil organic matter,while a smaller but slowly increasing proportion was retained in plant biomass.

AB - In order to follow the uptake and allocation of N in different plant functional types andmicrobes in two tundra ecosystems differing in nutrient availability, we performed a 15Nlabelingexperiment with three N forms and followed the partitioning of 15N labelamong plants, microorganisms and soil organic matter. At both sites the deciduousdwarf shrub Betula nana and the evergreen Empetrum hermaphroditum absorbed added15N at rates in the order: NH4+ . NO32 . glycine, in contrast to the graminoid Carexspecies which took up added 15N at rates in the orderNO32 . NH4+ . glycine. Carextransported a high proportion of 15N to aboveground parts, whereas the dwarf shrubsallocated most 15N to underground storage. Enhanced 13C in Betula nana rootsrepresents the first field evidence of uptake of intact glycine by this importantcircumpolar plant. Plant and microbial uptake of label was complementary as plantstook up more inorganic than organic N, while microbes preferred organic N. Microbesinitially took up a large part of the added label, but over the following four weeksmicrobial 15N decreased by 50% and most 15N was recovered in soil organic matter,while a smaller but slowly increasing proportion was retained in plant biomass.

U2 - 10.1657/1523-0430(06-114)[SORENSEN]2.0CO;2

DO - 10.1657/1523-0430(06-114)[SORENSEN]2.0CO;2

M3 - Journal article

SN - 1523-0430

VL - 40

SP - 171

EP - 180

JO - Arctic, Antarctic, and Alpine Research

JF - Arctic, Antarctic, and Alpine Research

IS - 1

ER -