TY - JOUR

T1 - N:P Ratio and the Nature of Nutrient Limitation in Calluna-Dominated Heathlands

AU - Oheimb, Goddert

AU - Power, Sally A.

AU - Falk, Kirsten

AU - Friedrich, Uta

AU - Mohamed, Abdelmenam

AU - Krug, Angelika

AU - Boschatzke, Nora

AU - Härdtle, Werner

N1 - Literaturverz. S. 326 - 327

PY - 2010/3/1

Y1 - 2010/3/1

N2 - There is growing evidence from different sources that prolonged high N deposition causes a shift from nitrogen (N) limitation to nitrogen and phosphorus (P) co-limitation or even P limitation in many terrestrial ecosystems. However, the number of ecosystems where the type of limitation has been directly tested by longer-term full-factorial field experiments is very limited. We conducted a 5-year fertilization experiment with N and P in the Lüneburger Heide (NW Germany) to test the hypothesis that, following decades of elevated atmospheric N inputs, plant growth in dry lowland heaths may have shifted from N to N-P co-limitation or P limitation. We also tested whether the plant tissue N:P ratio reflects the type of nutrient limitation in a continental lowland heathland. Experimental plots dominated by Calluna vulgaris received regular additions of N (50 kg N ha -1 y -1), P (20 kg P ha -1 y -1), a combination of both, or water only (control) from 2004 to 2008. Over the whole study period, a highly significant positive N effect on shoot length was found, thus indicating N limitation. We conclude that a clear shift from N limitation to N-P co-limitation or P limitation has not yet occurred. Tissue N:P ratios showed a high temporal variability and no relationship between tissue N:P ratio and the shoot length response of Calluna to nutrient addition was found. The N:P tool is thus of limited use at the local scale and within the range of N:P ratio observed in this study, and should only be used as a rough indicator for the prediction of the type of nutrient limitation in lowland heathland on a larger geographical scale with a broader interval of N:P ratio.

AB - There is growing evidence from different sources that prolonged high N deposition causes a shift from nitrogen (N) limitation to nitrogen and phosphorus (P) co-limitation or even P limitation in many terrestrial ecosystems. However, the number of ecosystems where the type of limitation has been directly tested by longer-term full-factorial field experiments is very limited. We conducted a 5-year fertilization experiment with N and P in the Lüneburger Heide (NW Germany) to test the hypothesis that, following decades of elevated atmospheric N inputs, plant growth in dry lowland heaths may have shifted from N to N-P co-limitation or P limitation. We also tested whether the plant tissue N:P ratio reflects the type of nutrient limitation in a continental lowland heathland. Experimental plots dominated by Calluna vulgaris received regular additions of N (50 kg N ha -1 y -1), P (20 kg P ha -1 y -1), a combination of both, or water only (control) from 2004 to 2008. Over the whole study period, a highly significant positive N effect on shoot length was found, thus indicating N limitation. We conclude that a clear shift from N limitation to N-P co-limitation or P limitation has not yet occurred. Tissue N:P ratios showed a high temporal variability and no relationship between tissue N:P ratio and the shoot length response of Calluna to nutrient addition was found. The N:P tool is thus of limited use at the local scale and within the range of N:P ratio observed in this study, and should only be used as a rough indicator for the prediction of the type of nutrient limitation in lowland heathland on a larger geographical scale with a broader interval of N:P ratio.

KW - Ecosystems Research

KW - Biology

KW - Calluna vulgaris

KW - Fertilization experiment

KW - Nitrogen deposition

KW - Nitrogen saturation

KW - Phosphorus limitation

KW - Plant growth

UR - http://www.scopus.com/inward/record.url?scp=77951768094&partnerID=8YFLogxK

U2 - 10.1007/s10021-010-9320-y

DO - 10.1007/s10021-010-9320-y

M3 - Journal articles

VL - 13

SP - 317

EP - 327

JO - Ecosystems

JF - Ecosystems

SN - 1432-9840

IS - 2

ER -