Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

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Positive shrub-tree interactions facilitate woody encroachment in boreal peatlands
Holmgren, M. ; Lin, C.Y. ; Murillo, J.E. ; Nieuwenhuis, A. ; Penninkhof, J.M. ; Sanders, N. ; Bart, T. van; Veen, H. van; Vasander, H. ; Vollebregt, M.E. ; Limpens, J. - \ 2015
Journal of Ecology 103 (2015). - ISSN 0022-0477 - p. 58 - 66.
scots pine - sphagnum - bogs - growth - mire - communities - recruitment - transitions - sylvestris - ecosystems
1. Boreal ecosystems are warming roughly twice as fast as the global average, resulting in woody expansion that could further speed up the climate warming. Boreal peatbogs are waterlogged systems that store more than 30% of the global soil carbon. Facilitative effects of shrubs and trees on the establishment of new individuals could increase tree cover with profound consequences for the structure and functioning of boreal peatbogs, carbon sequestration and climate. 2. We conducted two field experiments in boreal peatbogs to assess the mechanisms that explain tree seedling recruitment and to estimate the strength of positive feedbacks between shrubs and trees. We planted seeds and seedlings of Pinus sylvestris in microsites with contrasting water-tables and woody cover and manipulated both shrub canopy and root competition. We monitored seedling emergence, growth and survival for up to four growing seasons and assessed how seedling responses related to abiotic and biotic conditions. 3. We found that tree recruitment is more successful in drier topographical microsites with deeper water-tables. On these hummocks, shrubs have both positive and negative effects on tree seedling establishment. Shrub cover improved tree seedling condition, growth and survival during the warmest growing season. In turn, higher tree basal area correlates positively with soil nutrient availability, shrub biomass and abundance of tree juveniles. 4. Synthesis. Our results suggest that shrubs facilitate tree colonization of peatbogs which further increases shrub growth. These facilitative effects seem to be stronger under warmer conditions suggesting that a higher frequency of warmer and dry summers may lead to stronger positive interactions between shrubs and trees that could eventually facilitate a shift from moss to tree-dominated systems.
Preferential degradation of polyphenols from Sphagnum – 4-Isopropenylphenol as a proxy for past hydrological conditions in Sphagnum-dominated peat
Schellekens, J. ; Bindler, R. ; Martinez Cortizas, A. ; McClymont, E.L. ; Abbott, G.D. ; Biester, H. ; Pontevedra Pombal, X. ; Buurman, P. - \ 2015
Geochimica et Cosmochimica Acta 150 (2015). - ISSN 0016-7037 - p. 74 - 89.
pyrolysis mass-spectrometry - soil organic-matter - ombrotrophic peat - decomposition - lignin - nitrogen - bogs - vegetation - plants - carbon
The net accumulation of remains of Sphagnum spp. is fundamental to the development of many peatlands. The effect of polyphenols from Sphagnum on decomposition processes is frequently cited but has barely been studied. The central area of the Rödmossamyran peatland (Sweden) is an open lawn that consists mostly of Sphagnum spp. with a very low contribution from vascular plants. In order to determine the effects of decay on sphagnum phenols, 53 samples of a 2.7 m deep core from this lawn were analysed with pyrolysis gas chromatography–mass spectrometry (pyrolysis-GC–MS) and compared with more traditional decomposition proxies such as C/N ratio, UV light transmission of alkaline peat extracts, and bulk density. Factor analysis of 72 quantified pyrolysis products suggested that the variation in 4-isopropenylphenol was largely determined by aerobic decomposition instead of Sphagnum abundance. In order to evaluate the effects of aerobic decay in Sphagnum peat, down-core records from different climatic regions were compared using molecular markers for plant biopolymers and C/N ratio. These included markers for lignin from vascular plants ((di)methoxyphenols), polyphenols from Sphagnum spp. (4-isopropenylphenol), and cellulose (levoglucosan). Our results indicate that polyphenols from Sphagnum are preferentially degraded over polysaccharides; consequently the variability of the marker for sphagnum acid, 4-isopropenylphenol, was found indicative of decomposition instead of reflecting the abundance of Sphagnum remains. The fact that 4-isopropenylphenol is aerobically degraded in combination with its specificity for Sphagnum spp. makes it a consistent indicator of past hydrological conditions in Sphagnum-dominated peat. In contrast, the variability of C/N records in Sphagnum-dominated peat was influenced by both vegetation shifts and decomposition, and the dominant effect differed between the studied peatlands. Our results provide direction for modelling studies that try to predict possible feedback mechanisms between peatlands and future climate change, and indicate that the focus in Sphagnum decay studies should be on carbohydrates rather than on phenolic compounds.
Spatio-temporal trends of nitrogen deposition and climate effects on Sphagnum productivity in European peatlands
Granath, G. ; Limpens, J. ; Posch, M. ; Mücher, S. ; Vries, W. de - \ 2014
Environmental Pollution 187 (2014). - ISSN 0269-7491 - p. 73 - 80.
carbon accumulation - n deposition - boreal mire - bogs - growth - vegetation - impact - mosses - forest - emissions
To quantify potential nitrogen (N) deposition impacts on peatland carbon (C) uptake, we explored temporal and spatial trends in N deposition and climate impacts on the production of the key peat forming functional group (Sphagnum mosses) across European peatlands for the period 1900–2050. Using a modelling approach we estimated that between 1900 and 1950 N deposition impacts remained limited irrespective of geographical position. Between 1950 and 2000 N deposition depressed production between 0 and 25% relative to 1900, particularly in temperate regions. Future scenarios indicate this trend will continue and become more pronounced with climate warming. At the European scale, the consequences for Sphagnum net C-uptake remained small relative to 1900 due to the low peatland cover in high-N areas. The predicted impacts of likely changes in N deposition on Sphagnum productivity appeared to be less than those of climate. Nevertheless, current critical loads for peatlands are likely to hold under a future climate.
How Does Tree Density Affect Water Loss of Peatlands? A Mesocosm Experiment
Limpens, J. ; Holmgren, M. ; Jacobs, C.M.J. ; Zee, S.E.A.T.M. van der; Karofeld, E. ; Berendse, F. - \ 2014
PLoS ONE 9 (2014)3. - ISSN 1932-6203 - 11 p.
sphagnum mosses - vascular plants - carbon-dioxide - climate-change - boreal mire - scots pine - vegetation - bogs - evapotranspiration - table
Raised bogs have accumulated more atmospheric carbon than any other terrestrial ecosystem on Earth. Climate-induced expansion of trees and shrubs may turn these ecosystems from net carbon sinks into sources when associated with reduced water tables. Increasing water loss through tree evapotranspiration could potentially deepen water tables, thus stimulating peat decomposition and carbon release. Bridging the gap between modelling and field studies, we conducted a three-year mesocosm experiment subjecting natural bog vegetation to three birch tree densities, and studied the changes in subsurface temperature, water balance components, leaf area index and vegetation composition. We found the deepest water table in mesocosms with low tree density. Mesocosms with high tree density remained wettest (i.e. highest water tables) whereas the control treatment without trees had intermediate water tables. These differences are attributed mostly to differences in evapotranspiration. Although our mesocosm results cannot be directly scaled up to ecosystem level, the systematic effect of tree density suggests that as bogs become colonized by trees, the effect of trees on ecosystem water loss changes with time, with tree transpiration effects of drying becoming increasingly offset by shading effects during the later phases of tree encroachment. These density-dependent effects of trees on water loss have important implications for the structure and functioning of peatbogs.
Do plant traits explain tree seedling survival in bogs?
Limpens, J. ; Egmond, E. van; Li, B. ; Holmgren, M. - \ 2013
bogs - drought - mires - peatlands - seedlings - traits - trees - tree encroachment
Moss-dominated peat bogs store approximately 30% of global soil carbon. A climate induced shift from current moss-dominated conditions to tree-dominated states is expected to strongly affect their functioning and carbon sequestration capacity. Consequently, unraveling the mechanisms that may explain successful tree seedling establishment in these ecosystems is highly relevant. To assess the role of drought on early tree seedling establishment and the relative importance of plant traits in tree seedling survival, we conducted a factorial glasshouse experiment with seven conifer species. Our results show that drought inhibits moss growth, thereby increasing survival of tree seedlings. Survival success was higher in Pinus than in Picea species, ranking Pinus banksiana > Pinus sylvestris > Pinus nigra > Picea mariana > Picea glauca, Picea sitchensis > Picea rubens. We found that those species most successful under dry and wet conditions combined a fast shoot growth with high seed mass. We conclude that plant traits contribute to explaining successful early tree seedling establishment in bogs.
The use of molecular chemistry (pyrolysis-GC/MS) in the environmental interpretation of peat
Schellekens, J. - \ 2013
Wageningen University. Promotor(en): Thomas Kuijper, co-promotor(en): Peter Buurman. - Wageningen : Wageningen UR - ISBN 9789461737823 - 161
turf - veengronden - vegetatie - degradatie - sphagnum - gewasanalyse - vegetatietypen - pyrolyse - moleculaire technieken - chemie - veenmoerassen - peat - peat soils - vegetation - degradation - sphagnum - plant analysis - vegetation types - pyrolysis - molecular techniques - chemistry - bogs
Selecting parameters for the environmental interpretation of peat molecular chemistry - A pyrolysis-GC-MS study
Schellekens, J.F.P. ; Buurman, P. ; Pontevedra Pombal, X. - \ 2009
Organic Geochemistry 40 (2009)6. - ISSN 0146-6380 - p. 678 - 691.
soil organic-matter - chromatography mass-spectrometry - southern south-america - record - climate - carbon - bogs - preservation - peatlands - patterns
A number of samples from a deep peat bog in Tierra del Fuego were analyzed using pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) in order to extract parameters that might be used to interpret the peat chemistry in terms of vegetation change, anaerobic and aerobic decomposition, and fire incidence. The choice of parameters was based on factor analysis of 177 pyrolysis products, quantified for 13 samples, separated into extract and residue, as well as the total samples. Factor analysis of extracts, residues and total samples yielded similar classifications in terms of vegetation and decomposition. Pyrolysis products and ratios that most clearly differentiated samples were used to interpret the depth profile. Although interpretation was not always straightforward, indications of parameters to describe vegetation shifts, aerobic and anaerobic decomposition, and fire largely coincided. These parameters will be used in a forthcoming study for a more complete interpretation of the peat profile.
Response of Sphagnum species mixtures to increased temperature and nitrogen availability
Breeuwer, A.J.G. ; Heijmans, M.M.P.D. ; Berendse, F. ; Gleichman, J.M. ; Robroek, B.J.M. ; Limpens, J. - \ 2009
Plant Ecology 204 (2009)1. - ISSN 1385-0237 - p. 97 - 111.
n-deposition - water-level - nutritional constraints - decomposition rates - northern peatlands - litter quality - climate-change - peat formation - growth - bogs
To predict the role of ombrotrophic bogs as carbon sinks in the future, it is crucial to understand how Sphagnum vegetation in bogs will respond to global change. We performed a greenhouse experiment to study the effects of two temperature treatments (17.5 and 21.7°C) and two N addition treatments (0 and 4 g N m¿2 year¿1) on the growth of four Sphagnum species from three geographically interspersed regions: S. fuscum, S. balticum (northern and central Sweden), S. magellanicum and S. cuspidatum (southern Sweden). We studied the growth and cover change in four combinations of these Sphagnum species during two growing seasons. Sphagnum height increment and production were affected negatively by high temperature and high N addition. However, the northern species were more affected by temperature, while the southern species were more affected by N addition. High temperature depressed the cover of the `wet¿ species, S. balticum and S. cuspidatum. Nitrogen concentrations increased with high N addition. N:P and N:K ratios indicated P-limited growth in all treatments and co-limitation of P and K in the high N treatments. In the second year of the experiment, several containers suffered from a severe fungal infection, particularly affecting the `wet¿ species and the high N treatment. Our findings suggest that global change can have negative consequences for the production of Sphagnum species in bogs, with important implications for the carbon sequestration in these ecosystems
Soak systems of an Irish raised bog : a multidisiciplinary study of their origin, ecology, conservation and restoration
Crushell, P.H. - \ 2008
Wageningen University. Promotor(en): Matthijs Schouten; J.G.M. Roelofs. - S.l. : S.n. - ISBN 9789085852544 - 200
veenmoerassen - vegetatie - conservering - ecologie - ierse republiek - geschiedenis - ecologisch herstel - historische ecologie - natuurgebieden - herstelbeheer - bogs - vegetation - conservation - ecology - irish republic - history - ecological restoration - historical ecology - natural areas - restoration management
Soak systemen (systemen met een laagveenvegetatie omgeven door ombrotroof veen), kortweg soaks, zijn zeldzame elementen in hoogvenen die bijdragen aan de heterogeniteit van deze ecosystemen. Ze worden beschouwd als belangrijke elementen in het hoogveen die behouden en hersteld dienen te worden. Teneinde meer inzicht te krijgen in soak systemen, hebben wij historisch, biogeochemisch en ecologisch onderzoek verricht aan twee soaks in Clara bog
Precipitation determines the persistence of hollow Sphagnum species on hummocks
Robroek, B.J.M. ; Limpens, J. ; Breeuwer, A.J.G. ; Ruijven, J. van; Schouten, M.G.C. - \ 2007
Wetlands 27 (2007)4. - ISSN 0277-5212 - p. 979 - 986.
water-balance - growth - mosses - carbon - desiccation - tolerance - zonation - ecology - level - bogs
On raised bogs, the distribution of Sphagnum species is determined by their distance to the water table, but occasionally species are able to survive outside their niche. Hollow species that persist in hummock vegetation are assumed to profit from the higher water content of the surrounding hummock species, although the mechanism responsible is unclear. In this study, we elucidated the role of lateral hummock water transport (LHWT) and precipitation on the water content of hollow species occurring in hummocks. This was tested using a full factorial field transplantation experiment with cores of Sphagnum cuspidatum in a high and a low hummock. Treatments included direct precipitation (present or absent) and LHWT (present or absent). Fresh weights of the cores were measured at regular time intervals. Our results show a relatively large effect of precipitation on the water content in both the high and low hummock, whereas LHWT only seemed to be an important source of water in the high hummock, which was relatively dry. Furthermore, LHWT played an important role only after large precipitation events, suggesting that lateral water transport is indirectly affected by rain. This study shows that precipitation alone can explain the persistence of hollow species in high hummocks, whereas it was less important for hollow species in low hummocks. Our data suggest that survival and potential expansion of hollow species in higher hummocks is strongly depending on the intensity and frequency of rain events. Changes in precipitation patterns may result in a loss of Sphagnum diversity in hummocks.
Competition between Sphagnum mosses in European raised bogs : the effect of a changing climate
Robroek, B.J.M. - \ 2007
Wageningen University. Promotor(en): Matthijs Schouten; Frank Berendse, co-promotor(en): Juul Limpens. - [S.l.] : S.n. - ISBN 9789085047544 - 148
sphagnum - veenmoerassen - concurrentie tussen planten - water - fotosynthese - europa - natuurgebieden - sphagnum - bogs - plant competition - water - photosynthesis - europe - natural areas
De effecten van klimaatsveranderingen op ecosystemen domineren steeds vaker het nieuws. Toch is er nog maar weinig bekend over de effecten op hoogvenen, terwijl deze een grote rol spelen in het vastleggen van koolstof, een belangrijk element voor broeikasgassen. Veenmossen spelen daarin een cruciale rol. Bjorn Robroek toonde aan dat veranderingen in temperatuur, waterstanden en veranderende regenwater patronen, als gevolg van klimaatsveranderingen, een effect kunnen hebben op de veenmossamenstelling in hoogvenen. Als de huidige klimaatsscenario’s uit zullen komen, zullen vooral bultvormende soorten en soorten met een meer zuidelijke distributie gaan domineren. Maar ook dat de concurrentiekracht anders verandert bij verschuivingen in de beschikbaarheid van water
Onderzoek ten behoeve van het herstel en beheer van Nederlandse laagveenwateren; eindrapportage 2003-2006
Lamers, L. ; Geurts, J. ; Bontes, B. ; Sarneel, J. ; Pijnappel, H. ; Boonstra, H. ; Schouwenaars, J.M. ; Klinge, M. ; Verhoeven, J. ; Ibelings, B. ; Donk, E. van; Verberk, W. ; Kuijper, B. ; Esselink, H. ; Roelofs, J. - \ 2006
Ede : LNV-DK (Rapport DK nr. 2007/057-O) - 286
veenmoerassen - laagveengebieden - ecosystemen - ecologisch herstel - biodiversiteit - hydrologie - waterkwaliteit - waterbeheer - plassen - nederland - aquatische ecosystemen - biologisch waterbeheer - natura 2000 - bogs - fens - ecosystems - ecological restoration - biodiversity - hydrology - water quality - water management - ponds - netherlands - aquatic ecosystems - biological water management
Dit rapport presenteert de resultaten en conclusies van het onderzoek aan laagveenwateren binnen het kader van het Overlevingsplan Bos en Natuur in de eerste fase (obn, 2003-2006). In Hoofdstuk 3 wordt een overzicht gegeven van de onderzoekslocaties. Vervolgens worden in Hoofdstuk 4 de belangrijkste bevindingen van het correlatieve onderzoek naar de samenhang tusen biodiversiteit en milieukwaliteit gepresenteerd, met in Hoofdstuk 5 de rol van hydrologie in het laagveenlandschap. In de daaropvolgende hoofdstukken 6 tot en met 10 staan de onderzoeksvragen, methoden, resultaten en conclusies van de verschillende deelonderzoeken weergegeven met betrekking tot visstandsbeheer (Hoofdstuk 6), water- en veenkwaliteit (Hoofdstuk 7), verlanding en veenvorming (Hoofdstuk 8), voedselwebrelaties (Hoofdstuk 9) en fauna (Hoofdstuk 10). Ten slotte worden in Hoofdstuk 11 de belangrijkste conclusies van het onderzoek in de eerste fase samengebracht en bediscussieerd, in relatie tot de directe betekenis voor het laagveenbeheer. Dit zal uitgewerkt worden aan de hand van de nieuw gegenereerde kennis en bestaande literatuur over de betreffende milieuproblemen (‘ver’-thema’s), en de voor- en nadelen van beschikbare OBN-maatregelen. Als afsluiting wordt aan de hand van de resultaten in fase 1 aangegeven welke onderzoeksvragen geprioriteerd zijn voor de tweede fase
Moerasvogels op peil; deelrapport 3 werk in uitvoering: een evaluatie van beheersexperimenten gericht op het bevorderen van jonge verlandingsstadia
Huiskes, H.P.J. ; Beemster, N. ; Hommel, P.W.F.M. - \ 2005
Wageningen : Alterra (Alterra-rapport 828.3) - 62
moerassen - veenmoerassen - vogels - vegetatie - plantensuccessie - natuurbescherming - evaluatie - marshes - bogs - birds - vegetation - plant succession - nature conservation - evaluation
Dit rapport beschrijft aan de hand van een bureauevaluatie de effecten van 24 beheers¬experimenten gericht op de ontwikkeling van jonge verlandingsstadia. De geëvalueerde beheers¬ingrepen zijn onder te brengen in de 4 categorieën: waterdiepte, waterpeilfluctuatie, waterkwaliteit en vegetatiebeheer. De geselecteerde projecten zijn afkomstig uit de Database Moerasvogelprojecten, die benaderbaar is via de website Uit de evaluatie blijkt het grote belang van waterkwaliteit en waterpeilfluctatie voor het opgang brengen van een nieuwe verlandingscyclus. Wanneer in een later ontwikkelingsstadium getracht wordt een stagnerende verlanding weer te op gang te brengen zal veelal teruggegrepen moeten worden op drastische ingrepen, waaronder het drooglegging, vergroten van waterdiepte (o.a. door afgraven) en het uitvoeren van vegetatiebeheer (kappen van bos, maaien van riet)
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 - 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.
Onderzoek ten behoeve van het herstel en beheer van Nederlandse laagveenwateren
Geurts, J. ; Bontes, B. ; Pijnappel, H. ; Schouwenaars, J.M. ; Klinge, M. ; Kleef, H. van; Lamers, L. - \ 2004
[S.l.] : s.n. - 120
laagveengebieden - plassen - veenmoerassen - herstel - ecologie - waterkwaliteit - waterbeheer - hydrologie - monitoring - nederland - aquatische ecosystemen - fens - ponds - bogs - rehabilitation - ecology - water quality - water management - hydrology - netherlands - aquatic ecosystems
In dit eerste tussenrapport van het OBN-onderzoek aan laagveenwateren staan de resultaten van het onderzoek dat uitgevoerd werd in het afgelopen jaar. Hoofdstuk 3 geeft een beknopt overzicht van de onderzoekslocaties. In de volgende drie hoofdstukken presenteren de drie onderzoekers hun deelonderzoeken: hydrologie, water en veenkwaliteit (hoofdstuk 4), verlanding en veenvorming (hoofdstuk 5) en voedselwebrelaties (hoofdstuk 6). In hoofdstuk 7 wordt ingegaan op de specifieke problematiek met betrekking tot laagveenfauna en het streven naar de aanstelling van een vierde junior onderzoeker. Tenslotte zullen in hoofdstuk 8 de voornaamste conclusies op een rij worden gezet, waarbij aangegeven wordt hoe de onderzoeksresultaten vertaald kunnen worden naar terrein- en waterbeheer
Machines voor beheer van natte graslanden; een studie naar de kosten van beheer van natte en vochtige graslanden met aangepaste machines
Jong, J.J. de; Schaafsma, A.H. ; Aertsen, E.J.M. ; Hoksbergen, F.T.J. - \ 2003
Wageningen : Alterra (Alterra-rapport 747) - 45
bodems van waterrijke gebieden - veenmoerassen - overstroomde gronden - graslandbeheer - machines - wetland soils - bogs - flooded land - grassland management
In dit rapport is een studie beschreven naar aangepaste machines voor het maaien van natte graslanden. Er zijn onder verschillende omstandigheden tijdstudies verricht naar de machines. Op basis van informatie van de eigenaren van de machines zijn tarieven berekend. Daarnaast is informatie verzameld over het verwerken van maaisel. Onder beheerders van natte graslanden zijn de ervaringen met het gebruik van de verschillende machines geonventariseerd.
Relationships between ecotopes, hydrological position and subsidence on Clara Bog and Raheenmore Bog (Ireland)
Schaaf, S. van der; Streefkerk, J.G. - \ 2003
In: Measurement techniques and data assessment in wetlands hydrology / Ignar, S., Nowakowski, P., Okruszko, T., Warsaw : Warsaw Agricultural University Press - ISBN 8372444862 - p. 127 - 136.
veenmoerassen - veengronden - landschapsecologie - hydrologie - wetlands - ierse republiek - bogs - peat soils - landscape ecology - hydrology - irish republic
During the final stage of the Irish-Dutch raised bog study (1989-2001) an effort was made to integrate aspects of vegetation, water quality and hydrology. The basic ecological concept used was the ecotope rather than the plant community. This paper describes the two bogs, the ecotypes, followed by hydrological concepts. Afterwards relationships are developed and discussed
Growth reduction of Sphagnum magellanicum subjected to high nitrogen deposition: the role of amino acid nitrogen concentration
Limpens, J. ; Berendse, F. - \ 2003
Oecologia 135 (2003)3. - ISSN 0029-8549 - p. 339 - 345.
n deposition - atmospheric co2 - ammonium - nitrate - accumulation - metabolism - bogs - assimilation - vegetation - bryophytes
We tested the relationship between Sphagnum growth and the amount of nitrogen stored in free amino acids in a fertilisation experiment with intact peat monoliths in an open greenhouse in The Netherlands. Three nitrogen deposition scenarios were used: no nitrogen deposition, field conditions and a doubling of the latter, corresponding to 0, 40 and 80 kg N ham1 yearm1. Growth of Sphagnum as expressed by height increment was reduced in the 80 kg N treatment, but showed no correlation with the total nitrogen tissue concentration or with the concentration of individual or pooled free amino acids. The amount of nitrogen stored in free amino acids increased concomitantly with deposition, although it lagged more and more behind the total nitrogen concentration, the latter pointing to the accumulation of unmeasured nitrogen compounds. Asparagine clearly acted as the major storage compound for nitrogen in Sphagnum stem tissue, whereas arginine fulfilled this function to a lesser extent in the capitulum. It appears that nitrogen-induced growth inhibition of Sphagnum is related to acclimation rather than to certain threshold concentrations of amino nitrogen or total nitrogen. We propose that when Sphagnum is exposed to a step increase of nitrogen, its nitrogen metabolism does not adapt fast enough to keep up with the enhanced uptake rate. This imbalance between nitrogen uptake and assimilation may lead to an accumulation of toxic NH4+ in the cell and a subsequent reduction in growth
A numerical approach to 14C wiggle-match dating of organic deposits: best fits and confidence intervals
Blaauw, M. ; Heuvelink, G.B.M. ; Mauquoy, D. ; Plicht, J. van der; Geel, B. van - \ 2003
Quaternary Science Reviews 22 (2003). - ISSN 0277-3791 - p. 1485 - 1500.
radiocarbon age calibration - peat - samples - pollen - dates - bogs - ams - accumulation - netherlands - curve
C-14 wiggle-match dating (WMD) of peat deposits uses the non-linear relationship between C-14 age and calendar age to match the shape of a sequence of closely spaced peat C-14 dates with the C-14 calibration curve. A numerical approach to WMD enables the quantitative assessment of various possible wiggle-match solutions and of calendar year confidence intervals for sequences of C-14 dates. We assess the assumptions, advantages, and limitations of the method. Several case-studies show that WMD results in more precise chronologies than when individual C-14 dates are calibrated. WMD is most successful during periods with major excursions in the C-14 calibration curve (e.g., in one case WMD could narrow down confidence intervals from 230 to 36 yr). (C) 2003 Elsevier Science Ltd. All rights reserved.
Relationships between biotic and abiotic conditions on Clara Bog (Ireland)
Schaaf, S. van der; Streefkerk, J.G. - \ 2003
In: Ecohydrological processes in Northern wetlands / Järvet, A., Lode, E., [S.l.] : S.n. - p. 35 - 40.
veenmoerassen - veengronden - hydrologie - ierse republiek - ecohydrologie - bogs - peat soils - hydrology - irish republic - ecohydrology
During the final stage of the Irish-Dutch raised bog study (1989-2001) an effort was made to integrate aspects of vegetation, water quality and hydrology
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