Effect of climate change on soil nitrogen dynamics in a heathland

• Climate change is likely to affect all levels of the global biosphere. Nitrogen (N) is limiting for net primary production (NPP) in most terrestrial ecosystems and therefore a crucial factor for the ecosystem response to climate change. The hypothesis of progressive nitrogen limitation (PNL) predicts that if NPP is stimulated by elevated CO2 (eCO2), N will become limiting in the ecosystems over time, since the plants will sequester more N with increased carbon uptake (Luo et al. 2004). However, PNL tells nothing of the response of soil N cycling to eCO2. If turnover rates of N accelerate together with decreasing N losses it would lead to increased soil N availability, which would alleviate PNL (Rütting et al. 2010). The N cycle response to a changing climate is however still poorly understood. Only a few studies have investigated how ecosystems are affected by exposure to multiple climate factors and if responses are variable over time. This study is part of CLIMAITE (Climate change effects on biological processes in terrestrial ecosystems), simulating the projected climate conditions for Denmark in 2075 (Mikkelsen et al. 2008). We have investigated how the gross mineralization rates in a heathland are affected by climate change after 2 and 5 years of manipulation. The study site was exposed to three climate factors; eCO2, increased temperature and prolonged summer drought, both single and in combination, in a total of eight different treatments. We have measured the gross mineralization rates with stable isotope techniques in 2010 and compared with mineralization data from 2007. The aim of the study is to understand how climate change affects soil mineralization and if responses on soil nitrogen turnover vary over time of exposure to climate change. Results will be discussed in the light of changes in physico-chemical soil properties as well as compared to other studies.

Ämnesord

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Annan geovetenskap och miljövetenskap (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Other Earth and Related Environmental Sciences (hsv//eng)

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Klimatforskning (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Climate Research (hsv//eng)

Nyckelord

Climate manipulation

Nitrogen dynamics

Stable isotopes

Heath-land

CLIMAITE

FACE-experiment

N-tracing model

Mineralization

Nitrification

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