TY - JOUR

T1 - Differential effects of oxidised and reduced nitrogen on vegetation and soil chemistry of species-rich acidic grasslands

AU - Dorland, Edu

AU - Stevens, Carly J.

AU - Gaudnik, Cassandre

AU - Corcket, Emmanuel

AU - Rotthier, Suzanne

AU - Wotherspoon, Katherine

AU - Jokerud, Mari

AU - Vandvik, Vigdis

AU - Soons, Merel B.

AU - Hefting, Mariet M.

AU - Aarrestad, Per Arild

AU - Alard, Didier

AU - Diekmann, Martin

AU - Duprè, Cecilia

AU - Dise, Nancy B.

AU - Gowing, David J. G.

AU - Bobbink, Roland

PY - 2013/9

Y1 - 2013/9

N2 - Emissions and deposition of ammonia and nitrogen oxides have strongly increased since the 1950s. This has led to significant changes in the nitrogen (N) cycle, vegetation composition and plant diversity in many ecosystems of high conservation value in Europe. As a consequence of different regional pollution levels and of the increased importance of reduced N in the near future, determining the effect of different forms of N is an important task for understanding the consequences of atmospheric N inputs. We have initiated three replicated N addition experiments in species-rich, acidic grasslands spanning a climatic gradient in the Atlantic biogeographic region of Europe in Norway, Wales and France at sites with low levels of pollution. N was added in two doses (0 and 70 kg N ha−1 year−1 above background) and in three forms (oxidised N, reduced N and a 50–50 combination). After 2.5 years of N additions, the effects of these treatments on plant biomass, plant nutritional status, soil pH and soil nutrient availability were determined. Impacts of the N additions were observed within the 2.5-year research period. In some cases, the first signs of differential effects of N form could also be demonstrated. In the French site, for example, grass biomass was significantly increased by the oxidised N treatments but decreased by the reduced N treatments. In the Norwegian site, the reduced N treatments significantly reduced soil pH, whereas oxidised N did not. Effects on nutrient availability were also observed. These experiments will be continued to elucidate the longer term impacts of N deposition on these grasslands.

AB - Emissions and deposition of ammonia and nitrogen oxides have strongly increased since the 1950s. This has led to significant changes in the nitrogen (N) cycle, vegetation composition and plant diversity in many ecosystems of high conservation value in Europe. As a consequence of different regional pollution levels and of the increased importance of reduced N in the near future, determining the effect of different forms of N is an important task for understanding the consequences of atmospheric N inputs. We have initiated three replicated N addition experiments in species-rich, acidic grasslands spanning a climatic gradient in the Atlantic biogeographic region of Europe in Norway, Wales and France at sites with low levels of pollution. N was added in two doses (0 and 70 kg N ha−1 year−1 above background) and in three forms (oxidised N, reduced N and a 50–50 combination). After 2.5 years of N additions, the effects of these treatments on plant biomass, plant nutritional status, soil pH and soil nutrient availability were determined. Impacts of the N additions were observed within the 2.5-year research period. In some cases, the first signs of differential effects of N form could also be demonstrated. In the French site, for example, grass biomass was significantly increased by the oxidised N treatments but decreased by the reduced N treatments. In the Norwegian site, the reduced N treatments significantly reduced soil pH, whereas oxidised N did not. Effects on nutrient availability were also observed. These experiments will be continued to elucidate the longer term impacts of N deposition on these grasslands.

KW - European acidic grasslands

KW - Nitrogen deposition

KW - Nitrogen supply rate

KW - Oxidised nitrogen

KW - Reduced nitrogen

KW - Species richness

U2 - 10.1007/s11270-013-1664-4

DO - 10.1007/s11270-013-1664-4

M3 - Journal article

VL - 224

JO - Water, Air, and Soil Pollution

JF - Water, Air, and Soil Pollution

SN - 0049-6979

IS - 9

M1 - 1664

ER -