The impact of nitrogen deposition on carbon sequestration by European forests and heathlands

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Abstract:

<p style="margin: 0cm 0cm 0pt;" class="MsoNormal"><span style="font-size: small;"><span style="font-family: Times New Roman;"><span style="mso-ansi-language: EN-GB;" lang="EN-GB">In this study, we present estimated ranges in carbon (C) sequestration per kg nitrogen (N) addition in above-ground biomass and in soil organic matter for forests and heathlands, based on: (i) empirical relations between spatial patterns of carbon uptake and influencing environmental factors including nitrogen deposition (forests only), (ii) ¹⁵N field experiments, (iii) long-term low dose N fertilizer experiments and (iv) </span><span style="color: #000033;">results from ecosystem models.</span><span style="mso-ansi-language: EN-GB;" lang="EN-GB"> The results of the various studies are in close agreement and show that above-ground accumulation of carbon in forests is generally within the range 15-40 kg C/kg N. For heathlands, a range of 5-15 kg C/kg N has been observed based on low-dose N fertilizer experiments. The uncertainty in C sequestration per kg N addition in soils is larger than for above ground biomass and varies on average between 5-35 kg C/kg N for both forests and heathlands. All together these data indicate a total carbon sequestration range of 5-75 kg C/kg N deposition for forest and heathlands, with a most common range of 20-40 kg C/kg N. Results can not be extrapolated to systems with very high N inputs, nor to other ecosystems, such as peatlands, where the impact of N is much more variable, and may range from C sequestration to C losses. <o:p></o:p></span></span></span></p>