Effects of elevated CO2 and increased N deposition on bog vegetation in the Netherlands = [Gevolgen van een verhoogde atmosferische CO2-concentratie en N-depositie voor hoogveenvegetatie in Nederland]

Research output: Thesisinternal PhD, WU

Abstract

<p>Ombrotrophic bogs are important long-term sinks for atmospheric carbon. Changes in species composition of the bog plant community may have important effects on carbon sequestration, because peat mosses ( <em>Sphagnum</em> ) contribute more to peat accumulation than vascular plants. The aim of this study was to investigate the effects of elevated atmospheric carbon dioxide (CO <sub>2</sub> ) and increased nitrogen (N) deposition on bog vegetation in the Netherlands, with special attention to the relationship between peat mosses and vascular plants.</p><p>Three experiments were conducted, one outdoors and two in the greenhouse, in which peat monoliths were exposed to different levels of atmospheric CO <sub>2</sub> and N deposition. The outdoor experiment was part of the European BERI project, which used MiniFACE technology for creating elevated CO <sub>2</sub> conditions. The vegetation response in all three experiments was followed for two or three growing seasons. In addition, evapotranspiration and the partitioning of <sup>15</sup> N-labelled N deposition among <em>Sphagnum</em> , vascular plants and peat was measured.</p><p>The results showed, for the first time, that elevated CO <sub>2</sub> benefits growth of <em>Sphagnum</em> , but not necessarily at the cost of vascular plant growth. Increases in vascular plant biomass were non-significant, and were apparently restricted by the faster <em>Sphagnum</em> height growth and/or nutrient limitation. <em>Sphagnum</em> can take advantage of elevated CO <sub>2</sub> because its growth is less nutrient limited than that of vascular plants. Reductions in evapotranspiration at elevated CO <sub>2</sub> in summer would further benefit <em>Sphagnum</em> , as its growth is very sensitive to changes in moisture availability. During three growing seasons of N addition, the <em>Sphagnum</em> layer became saturated with N, resulting in a larger availability of N and better growth of vascular plants. After reaching a cover of about 60% vascular plants reduced <em>Sphagnum</em> growth through increased shading.</p><p>These changes in relative abundances of peat mosses versus vascular plants, in response to treatments and interactions between species, have implications for carbon sequestration in peat bogs. As elevated CO <sub>2</sub> favours <em>Sphagnum</em> growth, it is expected that carbon sequestration in bogs increases with increasing levels of atmospheric CO <sub>2</sub> . In contrast, increased N deposition will likely reduce carbon sequestration by increasing the relative abundance of vascular plants.</p><p><strong>Key words:</strong><sup>15</sup> N tracer, BERI, competitive interactions, elevated CO <sub>2</sub> , evapotranspiration, global change, MiniFACE, N deposition, ombrotrophic bog vegetation, plant species compostion, <em>Sphagnum</em> , vascular plants</p>
Original languageEnglish
QualificationDoctor of Philosophy
Awarding Institution
Supervisors/Advisors
  • Berendse, Frank, Promotor
  • van Breemen, N., Promotor
Award date18 Oct 2000
Place of PublicationS.l.
Print ISBNs9789058083074
Publication statusPublished - 2000

Keywords

  • moorlands
  • bogs
  • nitrogen
  • deposition
  • carbon dioxide
  • vegetation
  • environmental impact
  • climatic change
  • netherlands

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