Informatie voor professionals in voedsel en groen

Informatie voor professionals in voedsel en groen

  • externe gebruiker (Let opwarning)
  • Log in as
  • Over Groenekennis


    Groenekennis - Informatie voor professionals in voedsel en groen

    Groenekennis bevat artikelen uit vaktijdschriften, rapporten, video’s, presentaties, posters en websites op het gebied van landbouw, visserij, groene ruimte en voeding. Groenekennis wordt dagelijks bijgewerkt en bevat ongeveer 500.000 bronnen.

    Groenekennis is de globale view over diverse deelbestanden. Groenekennis is gevuld met alle informatie uit Groen Kennisnet, de Hydrotheek, Tuinpad, IB archief, ARTIK, bioKennis, Kennisbank Plantaardige bronnen, Kennisbank Zeldzame landbouwhuisdieren en afgesloten documentatiebestanden zoals Land Bodem Water en Consumenten- en huishoudstudies.

    Groen Kennisnet is een zeer belangrijk onderdeel van Groenekennis. De doelstelling van Groen Kennisnet is kennis delen op het gebied van Voedsel en Groen te bevorderen en te faciliteren voor een breed publiek.

    Bronnen in Groenekennis kunnen direct opgevraagd worden via een geavanceerde zoekmachine met een 'google-achtige' interface. Met filters kan ingezoomd worden op diverse aspecten, zoals Trefwoord, Collectie, Jaar en Auteur. Bovendien biedt Groenekennis gebruikers de mogelijkheid om via de E-mail geattendeerd te worden op aanvullingen in specifieke vakgebieden.
    De Tijdschriftenlijst biedt een overzicht van tijdschriften waaruit de artikelen voor Groenekennis worden geselecteerd. Door te klikken op een titel krijgt u alle artikelen uit dat tijdschrift in de Groenekennis database getoond.
    Zoeken op kaart biedt een geografische ingang op de beschikbare publicaties over de binnen dit bestand onderscheiden gebieden.

    Groenekennis is onderdeel van het bibliotheeksysteem van WUR. Praktijkgerichte publicaties en rapporten van WUR komen daardoor automatisch beschikbaar. Daarnaast wordt de database doorlopend gevuld met voor het groen onderwijs bruikbare bronnen en artikelen, video’s en websites. Het percentage online is de laatste jaren gegroeid tot tweederde van de totale aanwas per jaar. Dit percentage groeit nog steeds.

    Over
Record nummer 2057570
Titel Search performance and the spatial resource distribution
toon extra info.
Tom J. Huisman
Auteur(s) Huisman, T.J.
Uitgever Wageningen : Wageningen University
Jaar van uitgave 2014
Pagina's 100 pagina’s figuren, grafieken
Annotatie(s) Titel op omslag: Search performance & the spatial resource distribution  toon alle annotatie(s)
Proefschrift Wageningen University ter verkrijging van de graad van doctor in het jaar 2014
Met literatuuropgave. - Met samenvatting in het Engels en Nederlands
ISBN 9789461739391
Tutor(s) Prins, Prof. dr. H.H.T. ; Boer, Dr. W.F. de ; Langevelde, Dr. F. van
Promotiedatum 2014-05-27
Proefschrift nr. 5754
Samenvatting door auteur toon abstract

 

In the last decades research into movement has taken flight in ecology. The development and miniaturization of tracking devices has enabled ecologists to collect and store the movement data of a large and increasing number of animals and species. Next to this increase in available data new theoretical models have been developed and discussed at length in the ecological literature. These developments together form what has been called “movement ecology”. The research in this thesis falls squarely within this new field.

In movement ecology there has been a lot of attention for the analysis of movement paths and the comparison of these paths with random walks, which were first used for describing the random movement of particles in physics. These random walks were compared with respect to their ability to encounter resources (e.g. food items); the idea being that those random walks that are more efficient will have more encounters and will through natural selection be more likely to occur in nature. In the analysis of their search efficiency there was, however, relatively little attention for the spatial resource distribution. Especially when my PhD-research started only some basic models were used to describe the spatial resource distribution and used to test the effect on the search performance of random walks. For my research I therefore set myself the aim of determining how the spatial context influences the search efficiency of the main random walks used in ecology through simulation and to test this using experiments.

The first analysis of search efficiency with varying resource density and aggregation as described in chapter 2, shows that search efficiencies are dependent on both the resource aggregation and density as well as on their interaction. These results show that any analysis of search efficiency requires specification of both density and degree of aggregation. Furthermore, the effect of changes in either density or aggregation on the availability of resources may not be straightforward (e.g. linear with density). An optimally searching animal will have to switch between different random searches, depending on the resource distribution.

The next step (chapter 3) was to determine the influence of the spatial resource distribution when it was described and approached from the “patch” framework that is ubiquitous in ecology. In this framework it is the distribution of patch sizes (number of resources) that creates variation in the spatial distribution of resources.. The results show that it is not the variance in patch sizes, but the skewness of the patch-size distribution that determines the long-term search results of random walks. This is highly relevant since such skewed distributions are often seen in the distribution of plants, animals and resources. In addition the results indicate yet again that different distributions are best exploited by different random walks, and an efficient searcher would thus change movement depending on the spatial resource distribution.

Random walks are used for particles in physics and do not use information. Many animals do, however, use additional information in their search for food or resources. The use of information in foraging has been mainly studied in foraging theory. In chapter 4 I again studied the influence of the spatial resource distribution, but now with the searcher using information on past encounters. For this model I combined a random walk model with an information-use model from foraging theory. The results show that even when a searcher uses information on recent encounters an optimally searching animal will have to change its sensitivity depending on the spatial resource distribution.

On the basis of the simulations in the preceding chapters, for chapter 5 I conducted an experiment with carabid beetles. The beetles were allowed to forage in distributions varying in density and aggregation. The main hypothesis was that their movement patterns would change to be optimal in the respective distributions. The results showed, however, that the beetles did not change their movement behaviour with changes in the offered distribution. Based on this we expect the beetles’ main resource to have a distribution that is efficiently searched using their movement pattern, which means that their resources are expected to have a random spatial distribution, with relatively high density.

Finally in the 6thchapter I review the results from the previous chapters and conclude that optimal searchers need to adapt to the resource distribution when they use random searches or information on past encounter. I argue for more emphasis on and explicit study of the spatial distribution in movement ecology, and for integration of movement ecology and foraging theory to study the how foragers should deal with aggregation which is the fundamental challenge for both foraging theory and movement ecology .

Ultimately, by including landscape elements more rigorously and integrating movement ecology with existing fields such as invasion biology and foraging theory I believe it will be possible to truly include the movement process into ecological explanations and understanding, finally enabling researchers to provide clear first principle explanations and predictions not only for ecology, but also for the benefit of epidemiologists, nature conservation and wildlife management and thus for society as a whole.

Online full text
Op papier Haal het document, vind aanverwante informatie of gebruik andere SFX-diensten
Trefwoorden (cab) fauna / dierecologie / migratie / foerageren / telemetrie / diergedrag
Rubrieken Ecologie (algemeen)
Publicatie type Proefschrift
Taal Engels
Toelichting In de afgelopen decennia heeft het onderzoek naar bewegingspatronen in de ecologie een vlucht genomen. Door de ontwikkeling van alsmaar kleinere gps-transmitters en chips worden tegenwoordig de bewegingsgegevens van een enorm aantal dieren en soorten opgeslagen. Naast deze enorme toename in beschikbare gegevens is er een ontwikkeling geweest in de theoretische modellen die besproken en gebruikt worden in de ecologische literatuur. Al deze ontwikkelingen tezamen vormen de nieuwe subdiscipline van de zogenaamde bewegingsecologie en het onderzoek in dit proefschrift valt precies onder deze noemer.
Reacties
Er zijn nog geen reacties. U kunt de eerste schrijven!
Schrijf een reactie
 

To support researchers to publish their research Open Access, deals have been negotiated with various publishers. Depending on the deal, a discount is provided for the author on the Article Processing Charges that need to be paid by the author to publish an article Open Access. A discount of 100% means that (after approval) the author does not have to pay Article Processing Charges.

For the approval of an Open Access deal for an article, the corresponding author of this article must be affiliated with Wageningen University & Research.

U moet eerst inloggen om gebruik te maken van deze service. Login als Wageningen University & Research user of guest user rechtsboven op deze pagina.