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Biogeosciences An interactive open-access journal of the European Geosciences Union
Biogeosciences, 11, 6237-6250, 2014
https://doi.org/10.5194/bg-11-6237-2014
© Author(s) 2014. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
17 Nov 2014
Effects of seabird nitrogen input on biomass and carbon accumulation after 50 years of primary succession on a young volcanic island, Surtsey
N. I. W. Leblans1,2, B. D. Sigurdsson2, P. Roefs1, R. Thuys1, B. Magnússon3, and I. A. Janssens1 1Univ. of Antwerp, Dept. of Biology, 2610 Wilrijk, Belgium
2Agric. Univ. of Iceland, Hvanneyri 311 Borgarnes, Iceland
3Icelandic Inst. of Nat. Hist., 210 Gardabaer, Iceland
Abstract. What happens during primary succession after the first colonizers have occupied a pristine surface largely depends on how they ameliorate living conditions for other species. For vascular plants the onset of soil development and associated increase in nutrient (mainly nitrogen; N) and water availability is especially important. Here, we report the relationship between N accumulation and biomass and ecosystem carbon (C) stocks in a 50-year-old volcanic island, Surtsey, Iceland, where N stocks are still exceptionally low. However, a 28-year-old seagull colony on the island provided nutrient-enriched areas, which enabled us to assess the relationship between N stock and biomass and ecosystem C stocks across a much larger range in N stock. Further, we compared areas on shallow and deep tephra sands as we expected that deep-rooted systems would be more efficient in retaining N. The sparsely vegetated area outside the colony had accumulated 0.7 kg N ha−1 yr−1, which was ca. 50–60% of the estimated N input rate from wet deposition. This approximates values for systems under low N input and bare dune habitats. The seagulls have added, on average, 47 kg N ha−1 yr−1, which induced a shift from belowground to aboveground in ecosystem N and C stocks and doubled the ecosystem N-use efficiency, determined as the ratio of biomass and C storage per unit N input. Soil depth did not significantly affect total N stocks, which suggests a high N retention potential. Both total ecosystem biomass and C stocks were strongly correlated with N stock inside the colony, which indicated the important role of N during the first steps of primary succession. Inside the colony, the ecosystem biomass C stocks (17–27 ton C ha−1) had reached normal values for grasslands, while the soil organic carbon (SOC) stocks (4–10 ton C ha−1 were only a fraction of normal grassland values. Thus, it will take a long time until the SOC stock reaches equilibrium with the current primary production, during which conditions for new colonists may change.

Citation: Leblans, N. I. W., Sigurdsson, B. D., Roefs, P., Thuys, R., Magnússon, B., and Janssens, I. A.: Effects of seabird nitrogen input on biomass and carbon accumulation after 50 years of primary succession on a young volcanic island, Surtsey, Biogeosciences, 11, 6237-6250, https://doi.org/10.5194/bg-11-6237-2014, 2014.
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We studied the influence of allochthonous N inputs on primary succession and soil development of a 50-year-old volcanic island, Surtsey. Seabirds increased the ecosystem N accumulation rate inside their colony to ~47 kg ha-1 y-1, compared to 0.7 kg ha-1 y-1 outside it. A strong relationship was found between total ecosystem N stock and both total above- and belowground biomass and SOC stock, which shows how fast external N input can boost primary succession and soil formation.
We studied the influence of allochthonous N inputs on primary succession and soil development of...
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