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.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Of mice and oaks : conditional outcomes in a seed-dispersal mutualism
    Suselbeek, L. - \ 2014
    Wageningen University. Promotor(en): Herbert Prins; Frans Bongers, co-promotor(en): Patrick Jansen; Sip van Wieren. - Wageningen : Wageningen University - ISBN 9789462571020 - 120
    zaadverspreiding - verspreiding - mutualisme - knaagdieren - boomvruchten - sus scrofa - apodemus sylvaticus - ecologie - seed dispersal - dispersal - mutualism - rodents - tree fruits - sus scrofa - apodemus sylvaticus - ecology

    PhD Thesis (defence scheduled for 10 October 2014, 4pm) – abstracts for library

    Of Mice and Oaks: conditional outcomes in a seed-dispersal mutualism

    Lennart Suselbeek

    Abstract UK

    Rodents like to wood mouse store acorns to overcome winter, but some of the stored acorns are never retrieved by the rodents. Those acorns that are not retrieved have a chance to germinate and establish into a new tree. Thus, the interaction between mice and oaks is potentially mutualistic. However, the interaction is only mutualistic when the acorns are placed in locations where germination is likely to take place. The aim of this study was to investigate whether and how the strategy of hoarding (i.e. storing the seeds) depended on the presence of wild boar (who are very fond of acorns too!), de abundance of acorns and the abundance of mice in the area. Wild boar did not seem to be very capable to detect the acorns that had been hidden in the soil by the rodents, and as a consequence they seem to have little effect on the hoarding strategy of rodents. The abundance of rodents and of acorns does affect the hoarding patterns of rodents. With more competition (i.e. more mice or fewer acorns), seeds are hidden more quickly and are being scattered more widely. The acorns benefit from this, as their chance to survive and successfully establish as a new tree increases with dispersal distance and seed spacing.

    Abstract NL

    Muizen leggen een wintervoorraad aan van eikels, maar een deel van deze voorraad wordt vaak niet opgegeten door de muizen. De niet opgegeten eikels hebben een kans om zich te vestigen als nieuwe eik, en daarmee is de interactie tussen muizen en eiken in potentie een mutualisme. Echter, er is alleen sprake van een mutualisme als de eikels op goede kiemplaatsen terecht komen. Doel van deze studie was te onderzoeken of de verstopstrategie van muizen afhankelijk was de aanwezigheid van wilde zwijnen (die ook dol op eikels zijn!), van het aanbod aan eikels, en van het aantal muizen in het gebied. De wilde zwijnen lijken niet goed in staat te zijn om de door muizen in de grond verstopte eikels terug te vinden, en daardoor hebben zij weinig invloed op het hamstergedrag van de muizen. Het aantal eikels en muizen heeft wel invloed op de verstopstrategie. Hoe meer concurrentie (dus, meer muizen of juist minder eikels), hoe sneller en meer verspreid de zaden verstopt worden. De eikels profiteren daar van, want hoe beter ze verspreid worden des te groter hun overlevingskans.

    Het plantendispersiemodel DIMO; verbetering van de modellering in de Natuurplanner
    Wamelink, G.W.W. ; Jochem, R. ; Greft-van Rossum, J.G.M. van der; Grashof-Bokdam, C.J. ; Wegman, R.M.A. ; Franke, G.J. ; Prins, A.H. - \ 2011
    Wageningen : Wettelijke Onderzoekstaken Natuur & Milieu (WOt-werkdocument 241)
    vegetatie - zaadverspreiding - verspreiding van planten - zaadbanken - landgebruik - klimaatverandering - natuurgebieden - modellen - vegetation - seed dispersal - plant dispersal - seed banks - land use - climatic change - natural areas - models
    Verandering van landgebruik en de daaruit voortvloeiende versnippering maken de dispersie van soorten die afhankelijk zijn van natuurgebieden moeilijker. Daarbij komt dat als gevolg van klimaatverandering dispersie van plantensoorten belangrijker wordt. Om de effecten van deze veranderingen te kunnen inschatten op landelijke en later Europese schaal is het plantendispersiemodel DIMO ontwikkeld. Op basis van dispersiekenmerken voor wind, water en dierlijke dispersie, zaadbank en huidige voorkomen wordt de verspreiding van zaden en de vestiging van soorten op gridbasis gemodelleerd. Het model is gevalideerd voor de exoot Tengere rus (Juncus tenuis). Sinds de introductie in 1825 heeft deze soort zich vanuit drie punten over Nederland uitgebreid. Het model was goed in staat deze kolonisatie te simuleren. De verspreiding van de soort gebaseerd op waarnemingen sinds 1950 tot aan heden loopt ongeveer tien jaar voor op de modelsimulaties. Een belangrijk onderdeel dat nog mist in het model is het effect van waterdispersie. Hieraan wordt verder gewerkt.
    Weinig gevaar van distelzaad
    Zeeland, M.G. van; Hoek, H. - \ 2010
    Akker magazine 2010 (2010)10. - ISSN 1875-9688 - p. 19 - 19.
    onkruiden - cirsium arvense - verspreiding van planten - zaadverspreiding - onkruidbestrijding - weeds - cirsium arvense - plant dispersal - seed dispersal - weed control
    Telers zijn zeer beducht op de verspreiding van akkerdistelzaad uit natuurgebieden, omdat ze bang zijn voor veronkruiding van percelen. Toch blijkt deze verspreiding erg mee te vallen, zo blijkt uit veldproeven van PPO-AGV en PRI.
    DIMO 1.0.1.0 manual
    Malinowska, A.H. ; Greft-van Rossum, J.G.M. van der; Wamelink, G.W.W. - \ 2009
    Wageningen : Alterra (Alterra-rapport 1821) - 25
    verspreiding van planten - zaadverspreiding - degradatie - kieming - modellen - plant dispersal - seed dispersal - degradation - germination - models
    DIMO 1.0.1.0 is a plant dispersal model. It simulates plant dispersal in time, given (abiotic) suitability and species-specific characteristics. DIMO comprises three main processes: seed dispersal, seed-bank degradation and germination. The Manual for DIMO 1.0.1.0 consists of instructions on how to install the program, prepare the input data, run the model and uninstall the program.
    Natuurlijke verjonging van grove den; handvatten voor bosbeheerders
    Oosterbaan, A. ; Wolf, R.J.A.M. - \ 2006
    Vakblad Natuur Bos Landschap 3 (2006)3. - ISSN 1572-7610 - p. 11 - 13.
    bosbouw - natuurlijke verjonging - zaadverspreiding - groei van zaailingen - forestry - natural regeneration - seed dispersal - seedling growth
    Grove den is de meest voorkomende boomsoort in Nederland. Bij het huidige beheer van bossen wordt veel gebruik gemaakt van natuurlijke verjonging. De grove den speelt daarin een sleutelrol. Dit artikel geeft uitleg over kieming, vestiging en groei, concurrentie en komt met aanbevelingen voor beheer
    Risico-beoordelingen onkruiden in biologische landbouw (2) : rapportage over resultaten project Bio 3 in 2005 LNV-DWK programma 397V
    Riemens, M.M. ; Davies, J.A.R. ; Zeeland, M.G. van; Weide, R.Y. van der; Wijnker, J.P.M. ; Groeneveld, R.M.W. ; Kempenaar, C. - \ 2005
    Wageningen : Plant Research International (Nota / Plant Research International 371) - 32
    onkruiden - onkruidbestrijding - biologische landbouw - zaadverspreiding - simulatiemodellen - nederland - vollegrondsteelt - weeds - weed control - organic farming - seed dispersal - simulation models - netherlands - outdoor cropping
    Verslaglegging van resultaten betreffende het vervolgonderzoek naar mogelijke nadelige effecten van mechanische onkruidbestrijding op de ontwikkeling van ziekten en plagen in gewassen. Middels een enquête is de risicobeleving van de telers ten aanzien van ziekten en plagen geïnventariseerd. Tevens resultaten van het vervolgonderzoek naar de import van onkruidzaden op biologische bedrijven vanuit bermen en natuurterreinen, verkregen met een simulatiemodel gekoppeld aan een windroos en met risico-berekeningen op basis van beschikbare literatuurgegevens.
    Risico-beoordeling onkruiden in biologische landbouw
    Kempenaar, C. ; Bleeker, P.O. ; Kurstjens, D.A.G. ; Lamour, A. ; Molema, G.J. ; Groeneveld, R.M.W. ; Riemens, M.M. ; Weide, R.Y. van der - \ 2004
    onbekend : PRI Gewas- en Productie-ecologie (Nota / Plant Research International 326) - 64
    biologische landbouw - onkruidbestrijding - bodemstructuur - onkruiden - zaadverspreiding - grondbewerking - botrytis - risicoschatting - organic farming - weed control - soil structure - weeds - seed dispersal - tillage - botrytis - risk assessment
    In dit onderzoek zijn vier knelpunten bij de onkruidbeheersing in de biologische landbouw geselecteerd. Over deze vier knelpunten is zoveel mogelijk materiaal verzameld. Het gaat om het effect van mechanische onkruidbestrijding op de verspreiding van ziekten en plagen in gewassen en op het structuurbederf in de bodem, de veronkruiding van peen en ui in relatie tot het weer en andere factoren en het risico van de import van onkruidzaden uit bermen en natuurgebieden. Vanwege het ontbreken van kennis en de complexiteit van de situatie kan een risico-inschatting nog niet gemaakt worden. Nu zijn er per knelpunt vragen voor nader onderzoek opgesteld.
    Invoer van onkruiden op een bedrijf
    Scheepens, P.C. ; Groeneveld, R.M.W. ; Riemens, M.M. - \ 2004
    Wageningen : Plant Research International (Nota / Plant Research International 283) - 22
    overblijvende onkruiden - onkruiden - zaadverspreiding - biologische landbouw - perennial weeds - weeds - seed dispersal - organic farming
    Doelstelling van dit onderzoek is te inventariseren op welke wijzen onkruiden van buiten op het bedrijf terecht komen; trachten aan de hand van bestaande kennis in te schatten of routes meer of minder relevant zijn; een zo goed mogelijk kwantitatief beeld te geven van de belangrijkste routes; daarbij rekening te houden met de relatieve importantie van onkruidsoorten.
    Scatterhoarding and tree regeneration : ecology of nut dispersal in a Neotropical rainforest
    Jansen, P.A. - \ 2003
    Wageningen University. Promotor(en): Frans Bongers; Herbert Prins, co-promotor(en): Sip van Wieren. - [S.I.] : s.n. - ISBN 9789058087775
    zaadverspreiding - noten - carapa procera - knaagdieren - natuurlijke verjonging - zaadpredatie - zaadgrootte - natuurlijke selectie - tropische regenbossen - seed dispersal - nuts - carapa procera - rodents - natural regeneration - seed predation - seed size - natural selection - tropical rain forests - cum laude
    cum laude graduation (with distinction)
    Terugkeer van de zwarte populier op de oevers van de Rijntakken
    Lauwaars, S. ; Vosman, B. ; Coops, H. - \ 2000
    De Levende Natuur 101 (2000)1. - ISSN 0024-1520 - p. 3 - 6.
    natuurbescherming - herstel - salicaceae - populus nigra - rivieren - zaadverspreiding - rivieroeverbeplantingen - verspreiding - nederland - rijn - oevers - natuurtechniek - waal - uiterwaarden - nature conservation - rehabilitation - rivers - seed dispersal - riverside plantations - dispersal - netherlands - river rhine - shores - ecological engineering - river waal - river forelands
    Door de natuurontwikkeling op rivieroevers zijn er nieuwe kansen voor ooibossen en daarmee voor de zwarte populier gecreeerd. Langs de Rijn en de Waal is het verloop van de herkolonisatie onderzocht
    Distelproblematiek in het Rivierengebied. Deelproject 1: Verspreiding van akkerdistel vanuit natuurterreinen in de Gelderse Poort. Deelproject 2: Beheersingsmethoden van akkerdistel en ridderzuring in de Heesseltse waarden
    Lotz, L.A.P. ; Groeneveld, R.M.W. ; Zweerde, W. van der; Kempenaar, C. - \ 2000
    Wageningen : Plant Research International - 33
    asteraceae - cirsium arvense - rumex obtusifolius - distributie - onkruiden - plantengeografie - natuurreservaten - nationale parken - bouwland - zaadverspreiding - migratie - planten - nederland - gelderland - gelderse poort - asteraceae - cirsium arvense - rumex obtusifolius - distribution - weeds - phytogeography - nature reserves - national parks - arable land - seed dispersal - migration - plants - netherlands - gelderland - gelderse poort
    Muizen als zaadsjouwers en grasmaaiers
    Smit, R. ; Ouden, J. den - \ 2000
    Zoogdier 11 (2000)3. - ISSN 0925-1006 - p. 3 - 6.
    apodemus sylvaticus - microtus agrestis - clethrionomys glareolus - microtus arvalis - muizen - habitats - milieu - vegetatie - bossen - zaadpredatie - zaadverspreiding - zaden - verjonging - kieming - dierecologie - voedingsgedrag - voedingsgewoonten - bosecologie - mice - environment - vegetation - forests - seed predation - seed dispersal - seeds - regeneration - germination - animal ecology - feeding behaviour - feeding habits - forest ecology
    De invloed van muizen op de vegetatie, en het verband tussen de vegetatiestructuur en het voorkomen van de verschillende soorten muizen (bosmuis, rosse woelmuis, aardmuis, veldmuis; spitsmuizen buiten beschouwing gelaten). Resultaten van onderzoek in heiden en bossen op arme zandgronden van de Veluwe naar muizenbestand en zaadpredatie en zaadverspreiding. Muizen kunnen een enorm effect op de kieming van bomen hebben
    Dynamics of plant communities in field boundaries : restoration of biodiversity
    Schippers, P. - \ 2000
    Agricultural University. Promotor(en): M.J. Kropff; F. Berendse; W.J. Joenje. - S.l. : S.n. - ISBN 9789058082602 - 176
    vegetatie - ecosystemen - plantenecologische groepen - concurrentie tussen planten - planteninteractie - soortendiversiteit - synecologie - graslanden - systeemanalyse - simulatiemodellen - zaadverspreiding - zaden - biodiversiteit - vegetation - ecosystems - plant ecological groups - plant competition - plant interaction - species diversity - synecology - grasslands - systems analysis - simulation models - seed dispersal - seeds - biodiversity

    The field boundary, the strip of semi-natural vegetation bordering arable fields, can be considered as an important area for plant species survival in landscapes dominated by agriculture. In the last decennia, the natural plant species diversity has been reduced in many agricultural landscapes. Therefore, the objective of this thesis is to analyse factors determining biodiversity in field boundaries such as nutrient deposition from the arable field, mowing regime, level of disturbance and boundary dimensions. For this purpose a simulation model was constructed that comprises the processes and factors that determine the dynamics of the field boundary vegetation.

    This model is the result of the integration of three new models: a plant competition model based on eco-physiological principles, a spatially explicit population dynamical model and a seed dispersal model. The models were parameterized and evaluated with experimental data that were largely obtained from experiments described this thesis. Experimental research, therefore, was focussed on plant characteristics determining competition, succession and dispersal. Simulations and experimental results indicated that to enhance the diversity of the field boundary vegetation the following measures should be taken:

    1. Preventing all nutrient inputs from the arable field.
    2. Mowing and removal of the cuttings.
    3. Keeping the disturbance level under 20% of the area (y-1).
    4. Keeping the boundary as wide as possible but at at least wider than the maximum fertilizer misplacement.
    The role of bracken (Pteridium aquilinum) in forest dynamics = [De rol van adelaarsvaren (Pteridium aquilinum) in de bosdynamiek]
    Ouden, J. den - \ 2000
    Agricultural University. Promotor(en): F. Berendse; J. Fanta; F. Bongers. - S.l. : S.n. - ISBN 9789058082886 - 218
    pteridium aquilinum - bosecologie - plantensuccessie - allelopathie - ligstro - zaadverspreiding - zaadpredatie - concurrentie tussen planten - bosbedrijfsvoering - nederland - pteridium aquilinum - forest ecology - plant succession - allelopathy - litter - seed dispersal - seed predation - plant competition - forest management - netherlands

    Bracken fern ( Pteridium aquilinum ) causes stagnation in forest succession in many parts of the world. The mechanisms by which bracken affects the establishment and growth of plant species are studied, focusing on the regeneration of tree species in forest habitats.

    Bracken is well adapted to the forest environment. Data show that productivity is maintained under low light levels. When the tree canopy is opened up or removed, above-ground production increases sharply to produce dense swards. Under most tree species ( Pinus , Quercus , Larix , Betula ), the translucent canopies allow for the long term persistence of bracken clones. On the dry sandy soils of The Netherlands, beech ( Fagus sylvatica ) is the only tree species that can completely inhibit bracken growth. The relationship between bracken and ancient forests is mainly historical, and due to the lack of sporal regeneration and low survival of bracken outside the tree canopy cover.

    Under favourable conditions, bracken builds a physical structure that strongly reduces light levels available to plants growing under its canopy and smothers plants under collapsing and dead fronds. A field experiment indicated that below-ground competition by bracken is negligible. Species diversity of the forest understorey was negatively correlated with frond biomass.

    The slowly decaying litter builds a thick ectorganic soil layer that impedes establishment of light-seeded species. An experiment demonstrated how, besides bulk density and thickness, also the horizontal layering of the organic particles contributes to reduced species establishment on deep ectorganic soil layers. Despite numerous claims that the bracken plant produces substances that are toxic to other plants, experimental evidence did not confirm this allelopathic nature of bracken. A review of the literature suggested that the potential phytotoxicity of bracken is due to the release of compounds that protect the plant against herbivory.

    Field experiments showed that voles and mice make preferential use of the protective bracken cover. The increased abundance of rodents resulted in a high seed predation under bracken. The hoarding behaviour of wood mice ( Apodemus sylvaticus ) caused a directed dispersal of seeds towards the bracken structure. Bracken impinges on all causes of successional change in the vegetation. Tree establishment is blocked unless the clones are physically disturbed. Some implications for forest management are discussed.

    Key-words: allelopathy, bracken, competition, litter, Pteridium aquilinum, seed dispersal, seed predation, stagnation, succession.

    Marsilea quadrifolia L. (klaverbladvaren) nieuw voor Nederland
    Drok, W.J.A. ; Weeda, E.J. - \ 1999
    Gorteria 25 (1999)5. - ISSN 0017-2294 - p. 89 - 103.
    marsilea quadrifolia - planten - plantengemeenschappen - vegetatie - synecologie - plantenecologie - milieu - aquatische gemeenschappen - migratie - verspreiding - zaadverspreiding - invasie - plantengeografie - rivieren - bedreigde soorten - beschermde soorten - pioniersoorten - onderzoek - waal - zuid-holland - bommelerwaard - uiterwaarden - marsilea quadrifolia - plants - plant communities - vegetation - synecology - plant ecology - environment - aquatic communities - migration - dispersal - seed dispersal - invasion - phytogeography - rivers - endangered species - protected species - pioneer species - research - river waal - zuid-holland - bommelerwaard - river forelands
    In 1998 is deze watervaren, bekend als aquariumplant, aangetroffen in een uiterwaard van de Waal in de Bommelerwaard. Dit is 190 km noordelijker dan de tot dusver noordelijkste vindplaats. Verspreiding, achteruitgang, ecologie en plantensociologische aspecten van deze soort van Europese Rode Lijsten
    Weidekervel-torkruid (Oenanthe silaifolia M.Bieb.): terug van weggeweest
    Schaminée, J.H.J. ; Duistermaat, L.H. ; Veen, W. de; Klinckenberg, J.H.J. - \ 1999
    Gorteria 25 (1999)5. - ISSN 0017-2294 - p. 103 - 111.
    oenanthe (apiaceae) - planten - plantengemeenschappen - synecologie - vegetatie - oevervegetatie - oevergraslanden - plantenecologie - milieu - migratie - verspreiding - zaadverspreiding - rivieren - plantengeografie - bedreigde soorten - beschermde soorten - onderzoek - maas - limburg - uiterwaarden - oenanthe (apiaceae) - plants - plant communities - synecology - vegetation - riparian vegetation - riparian grasslands - plant ecology - environment - migration - dispersal - seed dispersal - rivers - phytogeography - endangered species - protected species - research - river meuse - limburg - river forelands
    Een sinds 1899 als uitgestorven beschouwde inheemse plant van natte graslanden werd opnieuw ontdekt op een kleidam langs de Maas bij Stevensweert (Limburg). Beschrijving, historisch voorkomen in Nederland, groeiplaats, en plantensociologische positie
    Ervaringen betreffende de verwildering van krokusoorten: Crocus chrysanthus (Herb.) in Nederland ingeburgerd?
    Londo, G. - \ 1998
    Gorteria 24 (1998)1. - ISSN 0017-2294 - p. 12 - 18.
    migratie - planten - verspreiding - zaadverspreiding - milieu - plantenecologie - iridaceae - bloembollen - migration - plants - dispersal - seed dispersal - environment - plant ecology - iridaceae - ornamental bulbs
    Het verwilderingsgedrag van verschillende soorten krokussen in verschillende typen grasland in de natuurtuin van de auteur in Scherpenzeel (Gld.). Met een beschrijving van de morfologische verschilkenmerken van de verwilderende soorten
    Migration rates of grassland plants along corridors in fragmented landscapes assessed with a cellular automaton model.
    Dorp, D. van; Schippers, P. ; Groenendael, J.M. van - \ 1997
    Landscape Ecology 12 (1997)1. - ISSN 0921-2973 - p. 39 - 50.
    natuurlijke graslanden - extensieve weiden - migratie - planten - verspreiding - zaadverspreiding - landbouwgrond - landschap - herstel - natuur - natuurtechniek - natural grasslands - rangelands - migration - plants - dispersal - seed dispersal - agricultural land - landscape - rehabilitation - nature - ecological engineering
    Seed dispersal in agricultural habitats and the restoration of species-rich meadows = Dispersie van zaden in cultuurlandschappen en het herstel van soortenrijke graslanden
    Dorp, D. van - \ 1996
    Agricultural University. Promotor(en): F. Berendse; J.M. van Groenendael. - S.l. : Van Dorp - ISBN 9789054855316 - 177
    plantengemeenschappen - gematigde klimaatzones - graslanden - hooiland - weiden - graslanden, gematigde streken - plantensuccessie - mens - migratie - planten - verspreiding - zaadverspreiding - flora - vegetatie - bescherming - conservering - natuurlijke graslanden - extensieve weiden - nederland - verstoring - plant communities - temperate zones - grasslands - meadows - pastures - temperate grasslands - plant succession - man - migration - plants - dispersal - seed dispersal - flora - vegetation - protection - conservation - natural grasslands - rangelands - netherlands - disturbance

    The restoration of species-rich meadows on former agricultural land in the Netherlands has a high priority, because these ecosystems have been disappearing rapidly due to eutrophication and acidification and falling water tables. In order to be able to restore such ecosystems on wet nutrient-poor soils, the suitability and accessibility of target sites have to be improved.

    The starting point for the restoration of species-rich meadows is frequently a soil that has been drained and enriched with fertilizers and polluted with pesticides for decades. Increasing the suitability of a site then involves ameliorating the habitat quality for the selected plant species by rewetting the soil, by reducing the availability of nutrients to plants through cutting and grazing and by removing the enriched topsoil, so that new individuals can establish. It is generally assumed that seeds are still available or will soon become available, This is not necessarily always the case. There are two alternative strategies by which plants may (re)colonize new sites; either through the germination of seeds buried in the soil or through the dispersal of seeds.

    In situations where soil seed banks have been depleted, dispersal of seeds from neighbouring sources via water, wind, animals and humans is the only natural option to restock a site with seeds. Since most grassland species have a limited dispersal capacity, the distances between seed sources and target sites become crucial. Ecological corridors could facilitate the dispersal of species in agricultural habitats if they satisfy the habitat requirements of the selected species.

    This thesis deals with a few aspects of the regeneration ecology of several meadow plant species (Chapters 1-5). Two questions are raised in particular: is it possible to restore species-rich meadows on previously farmed fields? and do ditch banks function as ecological corridors for species that are absent from a site undergoing restoration? To provide a contrast with typical grassland species, fleshy-fruited plant species and their specific dispersal characteristics have also been studied (Chapter 6).

    Chapter 1 describes the first phase of the restoration of species-rich meadows on former agricultural land in an intensively farmed landscape in the centre of the Netherlands. A comparison between the species pools of the former (pre1950) species-rich meadows, a set-aside area undergoing restoration and the ditch banks in the surrounding formed landscape, revealed that 106 out of the 145 meadow species of the former species-rich meadows were still present in refugia on ditch banks. Eighty-five out of these 145 meadow species have survived or already recolonized the set-aside area, but another 60 species has not yet recolonized the site due to insufficient seed dispersal, depleted soil seed banks and/or too few appropriate microsites in the vegetation for germination and establishment.

    An increase in the number of meadow species would be attainable if the accessibility and suitability of the site can be maximized. The effectiveness of the dispersal vectors water, humans and animals is extremely limited in the study area, leaving wind as the principal dispersal vector. Although some of the missing (extinct) species with long-range dispersal or permanent seed banks will reach the site without help, most species will not re-establish without being introduced deliberately.

    Chapter 2 analyses the dynamic distribution of ten perennial plant species typical of species-rich meadows in a Dutch agricultural landscape (220 ha). Mapping in 1990, 1991 and 1992 showed that ditch banks in the study area (comprising a set- aside area and the surrounding farmed landscape) form an important refugium for the selected species. Ditch banks were managed by regular mowing plus removal of the harvested biomass in the set-aside area and by grazing, mulching and dredging in the farmed landscape. In the setaside area, seven species were more frequent, whereas two species were less frequent. One species did not differ in frequency between the two areas.

    The distribution of the selected species varied greatly between years, suggesting frequent extinction and colonization events. This type of variation was expressed as E/C, i.e. the mean ratio of the number of extinctions and colonizations, The overall E/C index for all species and all years was 0.99. Four species appeared to be decreasing in distribution in the study area (E/C>1.0), six species appeared to be stable (E/C=1.0) or even increasing (E/C<1.0). A related index used was the proportion of cells that was occupied permanently (P/(T+P)).

    For the the selected plant species, the variation in the indices E/C and (P/(T+P)). was related to five life-history attributes (seed weight, dispersal mechanism, dispersal distance, ability to vegetatively spread and seed bank type) and proved to be not significantly associated. It is concluded that different combinations of life-history attributes (i.e. regeneration strategies) lead to species stability in this type of agricultural landscape.

    Chapter 3 explores the effects of five wind speeds (variable V: 2-13.5 m/s) and five release heights (variable H: 0.2-0.6 m) on the dispersal distances of seeds of six barochorous grassland perennials in a wind tunnel. The variation in dispersal distances within a seed population and between species with different aerodynamic attributes was expressed as 1-percentile, mode and 99-percentile values. Regression analyses showed that a model with three terms (V, V*H and V 2) best explained the variance in the dispersal distances across all species. According to the regression models, the dispersal distances of seeds in the tall of a frequency distribution (99-percentile values) increased exponentially with wind speed. At wind speeds of 14 m/s, predicted maximum distances were 10 to 15 m for small and relatively heavy spherical seeds and 20 to 30 m for large and relatively light cylindrical or disk-like seeds.

    A review of meteorological data showed that wind gusts>10 m/s at plant height occur at least annually. The long life-spans of plants of the selected species (up to several decades) suggests a large potential for long-range dispersal during their life-time. Individual populations appeared to be less isolated from other populations than can be inferred from distribution patterns of seed sources.

    Chapter 4 reports on the success of establishment after adding seeds of ten selected perennial plant species to a grassland undergoing restoration. The recolonization of former agricultural grasslands by perennial grassland species is assumed to be delayed or even prevented by a lack of seeds, by a lack of microsites offering opportunities for germination and establishment, or by both.

    Sampling the seed rain with sticky traps recorded the seeds of resident species and ubiquitous wind-dispersed species of the genera Betula, Cirsium and Epilobium. Given the spatial distribution of seed sources in the surrounding agricultural landscape and the limited dispersal capacity of the selected species, the fields of the restoration site are largely inaccessible. Lack of seeds was a major cause of their absence.

    Seeds of ten plant species were also added to a sward that was mown, clipped or from which the sod had been stripped. Established plants were allowed to grow for two years and then harvested. The establishment success of the selected species on sod-stripped plots was significantly higher than on mown or clipped plots. Differences between these treatments can be explained by the low density and short duration of gaps in the intact (mown and clipped) vegetation. Differences between species were related to seed weight; species with large heavy seeds had a significantly higher establishment success than species with small and light seeds. The lack of appropriate microsites, especially for species with small seeds, was another cause of their absence.

    Recruitment from old buried seeds is another recolonization route. Burial of seeds for two years revealed very low mortality rates in species with small, spherical and hard-coated seeds, and moderate mortality rates in species with seeds of high area/content ratios and direct germination. Species of the first group are expected to be frequently recruited from seeds buried in the soil when sod stripping has been applied.

    Chapter 5 explores the importance of linear landscape elements as ecological corridors. A cellular automaton model was built in order to determine the relative importance of the principal factors which determine the rate of migration of plants through corridors: the width and habitat quality of patches within a corridor (expressed as the population growth rate λ) and the dispersal capacity of plants (expressed as the slope αof the relationship between seed number and log-distance).

    Simulations with the model using different levels of the principal factors indicated highly significant and positive main effects of dispersal capacity, habitat quality and width of corridors on the rate of migration. Significant interactions existed for dispersal capacity x width and dispersal capacity x habitat quality, indicating that the effects of width and habitat quality depended on the dispersal capacity. In narrow corridors most of the dispersed seeds were deposited outside the corridor, which significantly reduced migration rates, especially for species with long-range dispersal of seeds. In wide corridors (up to 20 m), seed losses were much smaller and migration rates approximated those of continuous habitats. The contribution of the few longrange dispersed seeds to the rate of migration was significant when the quality of habitat patches was high. In all simulations, migration rates were <5 m/yr.

    Linear landscape elements are not effective corridors for plants with shortrange dispersal of seeds, because migration rates are low (<5 m/yr), high quality patches are few, and refugia and suitable habitat patches are frequently several kilometres apart, making a cohesive infrastructure for plants elusive.

    Chapter 6 deals with the dispersal interactions between fruit-eating birds and fleshy-fruited plants that grow on wooded banks in an agricultural landscape in Twenthe, Overijssel province, the Netherlands. Wooded banks are a characteristic feature of the landscape, but their density in the landscape is changing, i.e. in some areas wooded banks have been removed whereas new banks are being planted elsewhere. On average, there were 7 fleshy-fruited plant species per 100-m transect (the range was 2 to 14 species). The number of fleshy-fruited species of the transects did not correlate with the density of wooded banks or of woodland.

    Eight fruit-eating passerine bird species were regarded as the major avian seed dispersers. They were divided into longitudinal dispersers which carry the seeds of the majority of fleshy-fruited species over short (<0.1 km) distances only and transverse dispersers which carry the seeds of species with conspicuous fruit crops over larger distances (>0.1 km). Seed dispersal by longitudinal dispersers is limited to the network of wooded landscape elements whereas transverse dispersers frequently disperse seeds to and from dissimilar landscape elements.

    The bird-mediated seed rain on wooded banks was sampled in twelve transects by using 120 seed collectors and by systematically collecting bird droppings. The seed rain was dominated by Rubus fruticosus, Sorbus aucuparia, Rhamnus frangula, Lonicera periclymenum and Sambucus nigra. The density of the seed rain was 215 ± 68 seeds m -2. Most seeds (87,6%) were deposited during the fruiting period of the plant species involved; the rest (12.4%) was deposited when ripe fruits were no longer available or was deposited on transects where fruiting adults were absent and should be regarded as immigrants.
    In order to clarify the complex interactions between birds, plants and landscapes, the ecological differences between longitudinal and transverse dispersers deserve more attention. It will help to better predict the consequences of changing the density of wooded landscape elements on the species richness and distribution of fleshy-fruited plants in fragmented landscapes.

    Verspreidingskaarten van de botanische kwaliteit in Nederland uit FLORBASE
    Witte, J.P.M. ; Meijden, R. van der - \ 1995
    Gorteria 21 (1995). - ISSN 0017-2294 - p. 1 - 59.
    databanken - verspreiding - milieu - flora - habitats - cartografie - methodologie - migratie - nederland - plantengeografie - plantengemeenschappen - plantenecologie - planten - onderzoek - zaadverspreiding - technieken - vegetatie - thematische cartografie - databases - dispersal - environment - flora - habitats - mapping - methodology - migration - netherlands - phytogeography - plant communities - plant ecology - plants - research - seed dispersal - techniques - vegetation - thematic mapping
    Een nieuwe, eenvoudige bepaling van de (botanische) kwaliteit van de natuur in Nederland. De resultaten worden weergegeven in de vorm van verspreidingskaarten van 28 ecologische groepen (ecotoopgroepkaarten)
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