|Restoration of raised bogs: mechanisms and case studies from the Netherlands
Tomassen, H.B.M. ; Smolders, A.J.P. ; Schaaf, S. van der; Lamers, L.P.M. ; Roelofs, J.M.G. - \ 2010
In: Restoration of lakes, streams, floodplains and bogs in Europe (Wetlands, Ecology, Conservation and Management, 3 / Eiseltová, M., Springer Publishers - ISBN 9789048192649 - p. 285 - 330.
Mixing ratio and species affect the use of substrate-derived CO2 by Sphagnum
Limpens, J. ; Robroek, B.J.M. ; Heijmans, M.M.P.D. ; Tomassen, H.B.M. - \ 2008
Journal of Vegetation Science 19 (2008)6. - ISSN 1100-9233 - p. 841 - 848.
carbon-dioxide - water-content - photosynthesis - growth - permeability - desiccation - vegetation - mosses
Question: Can mixing ratio and species affect the use of substrate-derived CO2 by Sphagnum? Location: Poor fen in south Sweden and greenhouse in Wageningen, The Netherlands. Methods: Two mixing ratios of Sphagnum cuspidatum and S. magellanicum were exposed to two levels of CO2 by pumping CO2 enriched and non-enriched water through aquaria containing the species mixtures in the greenhouse. Results: Enhanced CO2 stimulated the production of S. cuspidatum, but only in aquaria co-dominated by S. magellanicum, coinciding with higher CO2 concentrations in the water layer. The denser growing S. magellanicum seemed to reduce gas escape from the water, resulting in accumulation of dissolved CO2. Adding CO2 did not affect species replacement. Conclusions: The use of substrate-derived CO2 for Sphagnum production depended on species identity and mixing ratio. The effect of mixing ratio on CO2 concentrations in the water layer suggests that species composition may affect both the efficiency with which substrate-derived CO2 is trapped and subsequently used. This could result in hitherto unexplored feedbacks between vegetation composition and gas exchange.
Expansion of invasive species on ombrotrophic bogs: desiccation or high N deposition?
Tomassen, H.B.M. ; Smolders, A.J.P. ; Limpens, J. ; Lamers, L.P.M. ; Roelofs, J.G.M. - \ 2004
Journal of Applied Ecology 41 (2004)1. - ISSN 0021-8901 - p. 139 - 150.
veenmoerassen - invasies - planten - stikstof - verdroging - veengronden - luchtverontreiniging - fosfor - drainage - betula pubescens - cladonia - molinia caerulea - sphagnum - nederland - ierse republiek - bogs - invasions - plants - nitrogen - desiccation - peat soils - air pollution - phosphorus - drainage - betula pubescens - cladonia - molinia caerulea - sphagnum - netherlands - irish republic - atmospheric nitrogen deposition - caerulea l moench - vulgaris l hull - calluna-vulgaris - molinia-caerulea - nutrient availability - cladonia-portentosa - vascular plants - growth
1. In many ombrotrophic bog areas the invasion of grass (e.g. Molinia caerulea) and tree (e.g. Betula pubescens) species has become a major problem. We investigated whether the invasion of such species is due to high atmospheric nitrogen (N) deposition by conducting a fertilization experiment. 2. The effects of experimentally increased N input on Molinia, Betula and Eriophorum vaginatum were studied in desiccated bog vegetation in Ireland, where there is relatively low background N deposition. Four different N treatments were applied for 3 years: 0 (control), 2, 4 and 8 g m-2 year-1. 3. Ammonium and nitrate concentrations in the peat moisture increased at high N addition rates, leading to significantly higher carbon : nitrogen (C : N) and nitrogen : phosphorus (N : P) ratios in the top layer of the peat. The potential CO2 production rate of the peat was not stimulated at high N addition rates due to severe acidification of the peat. 4. Despite high tissue N : P ratios (above 40), above-ground biomass production by Molinia was stimulated at high N addition rates, and foliar nutrient concentrations were unaffected. In contrast to Molinia, Betula and Eriophorum were unable to increase their above-ground biomass, probably due to P limitation. Regrowth of the lichen Cladonia portentosa was suppressed at high N addition rates. 5. Synthesis and applications. We conclude that the invasion of bogs by Molinia and Betula is likely to be less affected by desiccation than by increased N availability. Apparently, Molinia is well adapted to P-limiting conditions, which may explain its success in regions with increased N deposition levels. The high availability of P in many Dutch bogs compared with Irish bogs, together with prolonged high N deposition levels, may explain the strong increase in both Molinia and Betula observed in the Netherlands. As long as N and P availabilities in Dutch bogs are too high to prevent invasion of Betula and/or Molinia, management measures stimulating growth of Sphagnum mosses could probably reduce the negative effects of high N deposition levels.
Stikstofdepositie, eutrofiëring en nutriëntenkringloop
Limpens, J. ; Tomassen, H.B.M. - \ 2003
In: Onderzoek ten behoeve van herstel en beheer van Nederlandse hoogvenen : eindrapportage 1998-2001 / Tomassen, H,, Smolders, F., - p. 17 - 69.
hoogveengronden - nitraten - depositie - eutrofiëring - sphagnum - voedingsstoffen - vegetatie - zure regen - organisch bodemmateriaal - bog soils - nitrates - acid rain - deposition - nutrients - eutrophication - soil organic matter - vegetation - sphagnum
Venen bestaan bij de gratie van een positieve balans tussen productie en afbraak van organisch materiaal. In hoogveen zijn veenmossen cruciaal in dit verband. Hogere planten komen echter in het gedrang. Binnen het hoogveen-onderzoek zijn de effecten van stikstof op de verschillende plantenniveau's onderzocht
Expansion of Sphagnum fallax in bogs: striking the ballance between N and P availability
Limpens, J. ; Tomassen, H.B.M. ; Berendse, F. - \ 2003
Journal of Bryology 25 (2003). - ISSN 0373-6687 - p. 83 - 90.
atmospheric co2 - water level - deposition - competition - growth - vegetation - heterogeneity - decomposition - succession - bryophytes
Nitrogen deposition may cause shifts in the Sphagnum species composition of bogs, ultimately affecting the conservation value of these systems. We studied the effects of N and P on the expansion of S. fallax and S. flexuosum in bogs. We related historical census data of S. fallax, S. flexuosum, and four of their accompanying species to changes in N deposition. In addition, we conducted two fertilization experiments with N and P; one at a low deposition site with S. flexuosum and one at two high deposition sites with S. fallax. Finally, we related existing data on capitulum N and P concentrations of S. fallax to its abundance in the field. A relative increase in observed frequency of S. fallax coincided with an historical increase in N deposition in the Netherlands. There was no indication that S. fallax consistently outcompeted one of the other five Sphagnum species, the observed frequency of the Sphagnum species analysed was rather stable with time. The census data on S. flexuosum did not indicate a response to N deposition, but the species expanded at the low N deposition site when extra N was applied. In contrast, the expansion of S. fallax at the high deposition sites was limited by P. Organic nutrient concentrations suggested that when S. fallax can maintain a capitulum N concentration of 7 mg g(-1) or higher and a P concentration of 0.7 mg g(-1) or higher the species can grow to dominate. We conclude that S. fallax will gradually colonize an increasing number of new habitats in areas with a low, albeit increasing, N deposition, but will only grow to dominate when P supply is adequate. Then, the expansion of S. fallax may lead to ousting of the other Sphagnum species present.