Fate of airborne nitrogen in heathland ecosystems a - 15N tracer study
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In: Global Change Biology, Vol. 17, No. 4, 04.2011, p. 1549-1559.
Research output: Journal contributions › Journal articles › Research › peer-review
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T1 - Fate of airborne nitrogen in heathland ecosystems a - 15N tracer study
AU - Friedrich, Uta
AU - Falk, Kirsten
AU - Bahlmann, Enno
AU - Marquardt, Thorben
AU - Meyer, Hartmut
AU - Niemeyer, Thomas
AU - Schemmel, Siegfried
AU - Oheimb, Goddert
AU - Härdtle, Werner
PY - 2011/4
Y1 - 2011/4
N2 - In the present study, we analyze the fate of airborne nitrogen in heathland ecosystems (NW Germany) by means of a 15N tracer experiment. Our objective was to quantify N sequestration and N allocation patterns in an ecosystem that is naturally limited by N, but that has been exposed to airborne N inputs exceeding critical loads for more than 3 decades. We hypothesized that the system has a tendency towards N saturation, which should be indicated by low N sequestration and high N leaching. We analyzed 15N partitioning (aboveground biomass and soil horizons) and investigated 15N leaching over 2 years following a 15N tracer pulse addition. 15N tracer recovery was 90% and 76% in the first and second year, respectively. Contrary to our expectations, more than 99% of the tracer recovered was sequestered in the biomass and soil, while leaching losses were <0.05% after 2 years. Mosses were the most important short-term sink for 15N (64% recovery in the first year), followed by the organic layer. In the second year, the moss layer developed from a sink to a source (23% losses), and soil compartments were the most important sink (gains of 11.2% in the second year). Low 15N recovery in the current year's shoots of Calluna vulgaris (<2%) indicated minor availability of 15N tracer sequestered in the organic layer. N partitioning patterns showed that the investigated heaths still have conservative N cycling, even after several decades of high N loads. This finding is mainly attributable to the high immobilization capacities for N of podzols in soil compartments. In the long term, the podzol A- and B-horizons in particular may immobilize considerable amounts of incoming N. Since N compounds of these horizons are not readily bio-available, podzols have a high potential to withdraw airborne N from the system's N cycle.
AB - In the present study, we analyze the fate of airborne nitrogen in heathland ecosystems (NW Germany) by means of a 15N tracer experiment. Our objective was to quantify N sequestration and N allocation patterns in an ecosystem that is naturally limited by N, but that has been exposed to airborne N inputs exceeding critical loads for more than 3 decades. We hypothesized that the system has a tendency towards N saturation, which should be indicated by low N sequestration and high N leaching. We analyzed 15N partitioning (aboveground biomass and soil horizons) and investigated 15N leaching over 2 years following a 15N tracer pulse addition. 15N tracer recovery was 90% and 76% in the first and second year, respectively. Contrary to our expectations, more than 99% of the tracer recovered was sequestered in the biomass and soil, while leaching losses were <0.05% after 2 years. Mosses were the most important short-term sink for 15N (64% recovery in the first year), followed by the organic layer. In the second year, the moss layer developed from a sink to a source (23% losses), and soil compartments were the most important sink (gains of 11.2% in the second year). Low 15N recovery in the current year's shoots of Calluna vulgaris (<2%) indicated minor availability of 15N tracer sequestered in the organic layer. N partitioning patterns showed that the investigated heaths still have conservative N cycling, even after several decades of high N loads. This finding is mainly attributable to the high immobilization capacities for N of podzols in soil compartments. In the long term, the podzol A- and B-horizons in particular may immobilize considerable amounts of incoming N. Since N compounds of these horizons are not readily bio-available, podzols have a high potential to withdraw airborne N from the system's N cycle.
KW - Biology
KW - Calluna vulgaris
KW - dry lowland heath
KW - N cycling
KW - N deposition
KW - N retention
KW - N saturation
KW - Ecosystems Research
UR - http://www.scopus.com/inward/record.url?scp=79952063676&partnerID=8YFLogxK
U2 - 10.1111/j.1365-2486.2010.02322.x
DO - 10.1111/j.1365-2486.2010.02322.x
M3 - Journal articles
VL - 17
SP - 1549
EP - 1559
JO - Global Change Biology
JF - Global Change Biology
SN - 1354-1013
IS - 4
ER -