Sponsor: INTECOL
Co-Chairs:
Dr. Marcel R. Hoosbeek
Laboratory of Soil Science and Geology
Department of Environmental Sciences
Wageningen University
P.O. Box 37
Wageningen 6700 AA
The Netherlands
Phone: 31-317-484109
Fax: 31-317- 482419
E-mail: marcel.hoosbeek@bodeco.beng.wau.nl
and
Dr. Harri Vasander
Department of Forest Ecology
University of Helsinki
P.O. Box 24
Helsinki FIN-00014
Finland
Phone: 358-9-1917682
Fax: 358-9-1917605
E-mail: harri.vasander@helsinki.fi
Overview of Symposium:
The BERI project was funded by the European Commission and started in January of 1996. Nine partners from five EU countries are participating in this project contributing each their unique knowledge and experience to this bog ecosystem research initiative. The primary objective of the BERI project was to study, at five climatically different sites across Europe, the effects of elevated CO2 and N deposition on the net exchange of CO2 and CH4 between bogs and the atmosphere. Secondly, to study the effects of elevated CO2 and N deposition on the plant biodiversity of bog communities. These objectives further include the quantification of the impact of elevated CO2 and N, specifically: 1) on the population dynamics of different species of peatmoss and selected vascular plants; 2) on the growth of dominant species in the bog ecosystem; 3) on the organochemical and structural properties of dominant mire plants; 4) on the decomposability of litter from mire plants; and 5) on the emission of CH4 from the bogs. A process-oriented model was developed that simulates responses of botanical composition, C-sequestration and CH4 emission in bogs in Europe in response to possible scenarios of future changes in atmospheric CO2, N deposition and climate. In a series of about 8 papers the members of the BERI project will present a complete overview of the research findings.
Nico van Breemen and Marcel R. Hoosbeek, Department of Environmental Sciences, Wageningen University, Wageningen, The Netherlands; B. Wallen, Lund University, Lund, Sweden; H. Rydin, Uppsala University, Uppsala, Sweden; J.A. Lee, University of Sheffield, Sheffield, United Kingdom; J. Silvola, University of Joensuu, Joensuu, Finland; H. Vasander, University of Helsinki, Helsinki, Finland; F. Berendse, Department of Terrestrial Ecology and Nature Management, Wageningen University, Wageningen, The Netherlands; and Ph. Grosvernier, Natura Eng., Les Reussilles, Switzerland - Hypotheses, methods and major results of the Bog Ecosystem Research Initiative.
This is the first of a series of six papers that together comprise a symposium on the results of the BERI project. At five climatically different sites across Europe, we studied the effects of elevated CO2 and N deposition on 1) the net exchange of CO2 and CH4 between bogs and the atmosphere, and 2) the plant biodiversity of bog communities. At sites in Sweden, Finland, England, The Netherlands and Switzerland, the following four treatments are replicated five times:
Elevated atmospheric CO2 (560 ppm) in Mini-FACE rings
Ambient CO2 in Mini-FACE rings
Elevated N (5 g N /m2 /yr)
Ambient N
Preliminary analyses showed no significant treatment effects on the growth of Sphagnum and vascular plants, except for the Dutch site where Sphagnum length growth was 33% higher under elevated CO2, while vascular biomass was 53% higher under elevated N. Sphagnum growth was significantly reduced under elevated N due to increased shading by vascular plants. CH4 emissions increased with 4, 15, 20 and 33% in SE, FIN, CH and NL under elevated CO2.
Monique M.P.D. Heijmans, F. Berendse, and N. van Breemen, Wageningen University, Wageningen, The Netherlands; H. Rydin, Uppsala University, Uppsala, Sweden; A. Buttler, University of Neuchatel, Neuchatel, Switzerland; M.R. Hoosbeek, Department of Environmental Sciences, Wageningen University, Wageningen, The Netherlands; J.A. Lee, University of Sheffield, Sheffield, United Kingdom; E.A.D. Mitchell, University of Neuchatel, Neuchatel, Switzerland; S. Saarnio, University of Joensuu, Joensuu, Finland; H. Vasander, University of Helsinki, Helsinki, Finland; and B. Wallen, Lund University, Lund, Sweden - High N deposition affects competition between Sphagnum and other bog plant species.
We present results from four BERI-sites about relations between Sphagnum growth and cover of other bog plant species and the effects of elevated CO2 and increased N deposition on these relationships. Elevated CO2 had no clear effect, but in two out of four sites we found a negative effect of high cover of vascular plants or taller moss species brought about by high N deposition on Sphagnum growth. The two other sites had lower ambient N deposition and showed no effect of increasing N deposition on the competitive relationships between bog plant species. As Sphagnum contributes most to peat accumulation, i.e. carbon sequestration, these results imply that carbon sequestration in Sphagnum-dominated mire ecosystems is threatened by high N deposition.
Edward A.D. Mitchell, University of Neuchatel, Neuchatel, Switzerland; D. Gilbert, A. Buttler, University of Neuchatrel, Neuchatel, Switzerland; Ph. Grosvernier, Natura Eng., Les Reussilles, Switzerland; C. Albinsson, H. Rydin, Uppsala University, Uppsala, Sweden; M.M.P.D. Heijmans and M.R. Hoosbeek, Wageningen University, Wageningen, The Netherlands; A. Greenup, J. Foot, Countryside Council for Wales, Bangor, United Kingdom; T. Saarinen; H. Vasander, University of Helsinki, Helsinki, Finland; and J.-M. Gobat - Testate amoebae (Protozoa) and other micro-organisms in Sphagnum peatlands: biogeography, ecology and effect of elevated CO2.
Soil organisms and below ground processes receive very little attention in ecological and global change research in regard to their importance in ecosystem functioning.
In order to study the relationship between organization groups in Sphagnum peatlands, we analyzed the testate amoebae (Portozoa) communities, vegetation, and water chemistry of five Sphagnum peatlands across Europe (Switzerland, the Netherlands, Sweden, Finland, UK; EU project BERI - Bog Ecosystem Research Initiative). The comparison of vegetation and testate amoebae data showed that inter-site differences are more pronounced for the vegetation than for testate amoebae species assemblage. Testate amoebae represent a useful tool in multi-site studies and environmental monitoring of peatlands because: 1) the number of species in Sphagnum-dominated peatlands is much higher than for mosses or vascular plants, 2) most peatland testate amoebae species are cosmopolitan in their distributions, therefore they are less affected by biogeographical distribution patterns than plants; thus differences in testate amoebae assemblages can be interpreted primarily in terms of ecology, 3) testate amoebae are closely related to the ecological characteristics of the exact spot where they live; therefore they can be used to analyze and monitor small scale gradients that play a major role in the functioning of peatland ecosystems.
We further studied the effect of elevated CO2 on microbial communities in the same five Sphagnum peatlands using miniFACE (small size Free Air Carbon dioxide Enrichment) systems. In terms of biomass, heterotrophic bacteria, fungi, testate amoebae and micro-algae were the dominant groups of micro-organisms. Rotifera, nematoda, cyanobacteria, ciliates and flagellates accounted for only a low proportion of the microbial biomass. The contribution of different groups varied within the five sites and these differences could partly be explained by environmental conditions. Elevated CO2 increased the biomass of heterotrophic bacteria in all sites while other groups reacted differently depending on the sites. Nematoda, flagellates, nano- and micro-cyanobacteria, pico- and micro-algae, micro-euglenes biomass increased in most sites, while testate amoebae, ciliates, pico-cyanobacteria, nano- diatoms and algae, fungi and rotifera biomass declined in most sites. These changes suggest changes in community functioning that may have feedback effects on other components of the ecosystems.
Sanna Saarnio and J. Silvola, University of Joensuu, Joensuu, Finland; J. Foot, Countryside Council for Wales, Bangor, United Kingdom; I. Sundh, University of Uppsala, Uppsala, Sweden; A. Greenup, University of Sheffield, Sheffield, United Kingdom; M. Heijmans, Wageningen University, Wageningen, The Netherlands; A. Joabsson, Lund University, Lund, Sweden; E. Mitchell, University of Neuchatel, Neuchatel, Switzerland; and N. van Breemen, Wageningen University, Wageningen, The Netherlands - Effects of elevated CO2 and N deposition on CH4 emissions from european bogs.
Changes in the carbon cycle in wetlands could have significant impacts on the development of the global climate change. In BERI project, effects of raised CO2 or NH4NO3 supply on CH4 fluxes in bog ecosystems were investigated at five climatically different sites across Europe. In each site, ten study plots were enclosed with mini-FACE rings, five vented with CO2-enriched air (target 560 ppmv) and the other five with ambient air. Five other plots were sprayed with NH4NO3 solution six times during the growing season so that the cumulative addition of N was 3 g /m2 /a, except in the Netherlands 5 g /m2 /a. Control plots were sprayed with pure distilled water. Methane fluxes were followed over three growing seasons using a static chamber method and gas chromatographs (FID). Raised CO2 supply seemed to increase and raised NH4NO3 supply seemed to have no effects on CH4 fluxes in most of the sites. In each site, the differences between treatment and its control were statistically non-significant, even if the differences in vegetation, water table and peat temperature between study plots were taken into account. Our results indicate, over the short-term, a moderate increase in CH4 release under the increasing atmospheric CO2 concentration and no changes under increased N deposition.
Alison L. Greenup, University of Sheffield, Sheffield, United Kingdom; J.P. Foot, Countryside Council for Wales, Bangor, United Kingdom; G. Hall, Institute of Freshwater Ecology, Cumbria, United Kingdom; P. Ineson, ITE Merlewood, Cumbria, United Kingdom; J.A. Lee, University of Sheffield, Sheffield, United Kingdom; and D. Sleep, ITE Merlewood, Cumbria, United Kingdom - Isotopic insights into peatland CH4 dynamics under elevated CO2 and N deposition.
The use of stable C isotope ratios (13C/12C) has become an important tool for studying processes controlling CH4 formation, consumption, transport within and emission from peatlands. We performed laboratory incubations with intact peat cores to assess the effect of vegetation composition and depth of the water table on the magnitude of flux and isotopic composition of CH4. Experiments were performed under elevated and ambient N. Significantly greater CH4 release was observed from cores with vascular species possessing aerenchyma than from cores dominated by Sphagnum spp. The isotopic composition of CH4 emitted from Sphagnumcores was significantly more enriched in 13C than that emitted from cores with vascular plants. Enriched C isotope techniques were utilised to quantify CH4 oxidation, which was found to occur when the water table was lowered below the peat surface. When the water table was at the moss surface CH4 oxidation was minimal or inhibited. This has implications for the management of peatlands as sources or sinks for trace gases, since the results of this study suggest that any change leading to an increase in the coverage of plants with aerenchyma, or an increase in the height of the water table, would lead to a concomittant increase in CH4 emissions.
Marcel R. Hoosbeek, Department of Environmental Sciences, Wageningen University, Wageningen, The Netherlands; F. Berendse, Department of Terrestrial Ecology and Nature Management, Wageningen University, Wageningen, The Netherlands; J. Foot, Countryside Council for Wales, Bangor, United Kingdom; A. Greenup, University of Sheffield, Sheffield, United Kingdom; Ph. Grosvernier, Natura Eng., Les Reussilles, Switzerland; E.A.D. Mitchell, University of Neuchatel, Neuchatel, Switzerland; H. Rydin, Uppsala University, Uppsala, Sweden; T. Saarinen; S. Saarnio, University of Joensuu, Joensuu, Finland; and B. Wallen, Lund, University, Lund, Sweden - Modeling the effects of elevated CO2 and N on the biogeochemistry of European bogs.
This is the last of a series of papers that constitute a symposium on the results of the BERI project. This paper focuses on chemical analyses and biogeochemical modeling. The CO2 treatment had no effect on the C/N ratio of Sphagnum and major vascular plants, except for the Swiss site where the C/N ratio of Sphagnum significantly increased. Under elevated N deposition the C/N ratio of Sphagnum decreased significantly in FI, SW, NL and CH. The elevated N effect on the C/N ration of vascular plants was not significant, except for one species in FI and one species in NL. Waterchemical data collected at the beginning, middle and end of the 1997 growing season suggested P limited growing conditions for part of the season. A biogeochemical model was developed as a means to compare the sites along the transects and to explore several climate scenarios. Sphagnum and vascular plants compete for light and nutrients and provide input to litter and peat pools.
