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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    Populatiebeheer van wilde hoefdieren: nog niet goed op orde
    Groot Bruinderink, G.W.T.A. ; Grift, E.A. van der - \ 2015
    Vakblad Natuur Bos Landschap (2015)december. - ISSN 1572-7610 - p. 26 - 29.
    wilde dieren - wildbescherming - wildbeheer - hoefdieren - regionaal beleid - populatiedichtheid - populatie-ecologie - bevolkingsspreiding - habitats - wild animals - wildlife conservation - wildlife management - ungulates - regional policy - population density - population ecology - population distribution - habitats
    In de afgelopen vijftig jaar groeide in grote delen van Europa, inclusief Nederland, zowel de aantallen als de verspreiding van ree, wild zwijn, damhert en edelhert. Verklaringen hiervoor zijn een betere bescherming en beheer, ontsnappingen, spontane (her)kolonisatie van leefgebieden in combinatie met (her) introducties, verbetering van connectiviteit, mildere winters en een verhoogd voedselaanbod. Tot voor kort werd de verspreiding van wild zwijn en edelhert in Nederland gehinderd door rijksbeleid: de soorten mogen alleen op de Veluwe, de Oostvaardersplassen en Nationaal park De Meinweg leven. Inmiddels zijn de provincies verantwoordelijk voor het faunabeleid en de kans is groot is dat wilde hoefdieren in de nabije toekomst verder zullen toenemen.
    Resource ecology : spatial and temporal dynamics of foraging
    Prins, H.H.T. ; Langevelde, F. van - \ 2008
    Dordrecht : Springer (Wageningen UR Frontis series vol. 23) - ISBN 9781402068485 - 304
    natuurlijke hulpbronnen - hulpbronnenbeheer - ecologie - herbivoren - begrazing - foerageren - voeropname - dieetstudies - bevolkingsspreiding - kuddes (herds) - vee - migratie - voedingsgedrag - ruimtelijke verdeling - grote grazers - plant-herbivoor relaties - natural resources - resource management - ecology - herbivores - grazing - foraging - feed intake - diet studies - population distribution - herds - livestock - migration - feeding behaviour - spatial distribution - large herbivores - plant-herbivore interactions
    This multi-author book deals with 'resource ecology', which is the ecology of trophic interactions between consumers and their resources. Resource ecology is perhaps the most central part of ecology. In its linkage between foraging theory and spatial ecology, it shows how old and fundamental questions can be tackled afresh. It addresses crucial aspects of the interactions between consumers and resources. Foraging is the central process in resource ecology because it leads to growth, survival and reproduction of the animal. Resource ecology forms the basis for comprehending the functioning of multi-species assemblages, and is thus key to grasp the organisation of biodiversity. For the purposes of stimulating future research, each chapter ends with two or three testable hypotheses. Each chapter is followed by a comment. This makes the book ideal for teaching and course work, because it highlights the fact that ecology is a living and active research field.
    Reisverslag Atlanto-Skandische haring survey, FRV Dana 2 - 31 mei 2007
    Couperus, A.S. ; Beek, F.A. van - \ 2007
    IJmuiden : IMARES (Rapport / Wageningen IMARES nr. 07.014) - 8
    visserij - haringen - vangstsamenstelling - opbrengsten - vistuig - akoestisch sporen - populatiedynamica - bevolkingsspreiding - migratie - inventarisaties - zeevisserij - visvangsten - onderwaterakoestiek - noordelijke atlantische oceaan - fisheries - herrings - catch composition - yields - fishing gear - acoustic tracking - population dynamics - population distribution - migration - inventories - marine fisheries - fish catches - underwater acoustics - north atlantic
    Het kokkelbestand in de Nederlandse kustwateren in 2007
    Kesteloo-Hendrikse, J.J. ; Stralen, M.R. van; Fey-Hofstede, F.E. ; Jol, J.G. ; Goudswaard, P.C. - \ 2007
    Yerseke : IMARES (Rapport / Wageningen IMARES nr. C071/07) - 44
    schaal- en schelpdierenvisserij - kokkels - populatiedichtheid - bevolkingsspreiding - populatiegroei - statistiek - nederland - visvangsten - visgronden - waddenzee - schelde - zuidwest-nederland - shellfish fisheries - clams - population density - population distribution - population growth - statistics - netherlands - fish catches - fishing grounds - wadden sea - river scheldt - south-west netherlands
    In opdracht van LNV is (tbv het beleid voor kokkelvisserij, zoals neergelegd in EVA II) in voorjaar 2007 het kokkelbestand in de Oosterschelde, Westerschelde, Waddenzee en de Voordelta geïnventariseerd
    Exoten
    Vaate, A. bij de; Winter, H.V. - \ 2005
    Lelystad : RIZA (RIZA Rapport 2005.010) - ISBN 9789036957120
    vissen - aquatische gemeenschappen - geïntroduceerde soorten - bevolkingsspreiding - aquatische ecosystemen - fishes - aquatic communities - introduced species - population distribution - aquatic ecosystems
    Een aanzienlijk deel van de macrofauna op harde substraten bestaat uit exoten. Dat kan problemen opleveren bij de beoordeling voor de Kaderrichtlijn Water. Ook onder de vissen komen exoten voor, maar slechts in kleine aantallen
    Discard reconstruction method used in the assessment of North Sea plaice in 2004: product A3b van het F-project
    Keeken, O.A. van; Pastoors, M.A. ; Rijnsdorp, A.D. - \ 2005
    IJmuiden : RIVO (Report / RIVO-Netherlands Institute for Fisheries Research no. C032/05) - 20
    schol - beoordeling - populatiedichtheid - bevolkingsspreiding - visbestand - noordzee - visstand - visserijbiologie - discards - plaice - assessment - population density - population distribution - fishery resources - north sea - fish stocks - fishery biology - discards
    Spatial and temporal fluctuations in bacteria, microfauna and mineral nitrogen in response to a nutrient impulse in soil
    Zelenev, V.V. - \ 2004
    Wageningen University. Promotor(en): Ariena van Bruggen, co-promotor(en): A.M. Semenov. - Wageningen : s.n. - ISBN 9789058089885 - 190
    bodembiologie - bodemfauna - micro-organismen - bacteriën - biologische bodemactiviteit - rizosfeer - variatie - oscillatie - populatiedynamica - bevolkingsspreiding - organisch bodemmateriaal - organisch afval - voedingsstoffen - wiskundige modellen - simulatiemodellen - soil biology - soil fauna - microorganisms - bacteria - biological activity in soil - rhizosphere - variation - oscillation - population dynamics - population distribution - soil organic matter - organic wastes - nutrients - mathematical models - simulation models
    Fluctuations of bacterial populations can be observed when frequent and sufficiently long series of samples are obtained for direct microscopic or plate counts of bacteria. Such fluctuations in time and space have been observed for both bacteria and other soil inhabitants. These fluctuations of bacterial numbers are especially noticeable after some disturbance of soil such as tillage, drying and rewetting, and substrate addition, for example in the form of fresh plant material. However, very seldom were bacterial fluctuations subjected to proper statistical analysis to detect significant periodical components in the analyzed data (Chapter 1). The phenomenon of wave-like bacterial oscillations was investigated in short-term (1 month) controlled experiments for rhizosphere and bulk soil after substrate input from plant roots and fresh plant debris, respectively. Short-term oscillating dynamics of bacterial populations were simulated in a mechanistic model, which may contribute significantly to our understanding of the reasons and consequences of bacterial oscillations after addition of substrate to soil.



    To determine the spatial variation in density of different trophic bacterial groups (copiotrophic and oligotrophic) and carbon sources in the rhizosphere, colony-forming units (CFUs) and soluble total organic carbon (TOC) were quantified along the root from rhizosphere and corresponding bulk soil samples at 2 cm intervals along wheat roots two, three, and four weeks after planting (Chapter 2). There was a moderate rhizosphere effect in one experiment with soil rich in fresh plant debris (1% C in soil), and a very pronounced rhizosphere effect in the second experiment with soil low in organic matter (0.7% C). Wave-like patterns of both trophic groups of bacteria as well as TOC could be discerned along the whole root length (60 or 90 cm). Harmonical analysis revealed significant oscillations in bacterial populations and TOC. TOC concentrations were maximal at the root tip and base and minimal in the middle part of the roots. Populations of copiotrophic and oligotrophic bacteria had two maxima close to the root tip and at the root base, or three maxima close to the tip, in the middle section, and at the root base. Phases and periods of the two trophic groups differed slightly. The location and pattern of the waves in bacterial populations changed progressively from week to week, and was not consistently correlated with TOC concentrations or the location of lateral root formation. Thus, the traditional view that patterns in bacterial numbers along the root directly reflect patterns in exudation and rhizodeposition from several fixed sources along the root may not be true. We attributed the observed wave-like patterns in bacterial populations to bacterial growth and death cycles (due to autolysis or grazing by predators). Considering the root tip as a moving nutrient source, temporal oscillations in bacterial populations at any location where the root tip passed would result in moving waves along the root. This change in concept about bacterial populations in the rhizosphere could have significant implications for plant growth promotion and soil health.



    To check the hypothesis that the principal mechanism underlying the wave-like distribution of bacteria along the root is a cycle of growth, death, autolysis, and regrowth of copiotrophic bacteria in response to a moving substrate source (root tip) a simulation model was created (Chapter 3). After transformation of observed spatial data to presumed temporal data based on root growth rates, a simulation model was constructed with the Runge-Kutta integration method to simulate the dynamics of colony-forming bacterial biomass, with relative growth and death rates depending on substrate content so that the rate curves crossed over at a substrate concentration within the range of substrate availability. The original source of substrate was the root tip, supplemented with a background flux (BGF) of substrate from soil organic matter and dead root cells. Dead necromass from bacteria was partially recycled into substrate. This model was named "BACWAVE", standing for 'bacterial waves'. The model generated cyclic dynamics of bacteria, which were translated into traveling spatial waves along a moving nutrient source. Parameter values were estimated from calculated initial substrate concentrations and observed microbial distributions along wheat roots by an iterative optimization method. The kinetic parameter estimates fell in the range of values reported in the literature. The model was validated with an independent data set of bacteria along wheat roots in relatively C-rich soil. Calculated microbial biomass values produced spatial fluctuations similar to those obtained for experimental biomass data derived from colony forming units. Concentrations of readily utilizable substrate (RUS) calculated from biomass dynamics did not mimic measured concentrations of TOC, which consists not only of substrate but also various polymers and humic acids. Thus, a moving impulse of nutrients into soil resulting in cycles of growth and death of bacteria can explain the observed phenomenon of moving bacterial waves along roots. This was the first report of wave-like dynamics of micro-organisms in soil along a root resulting from the interaction of a single organism group with its substrate.



    The model "BACWAVE" for wave-like dynamics of copiotrophic bacteria (CB) was extended to include dynamics of oligotrophic bacteria (OB) (Chapter 4). CFUs ofOBand CB along wheat roots (24 samples) in a low C soil were transformed to temporal biomass taking root growth rate and cell sizes into account. Growth rates of both groups of bacteria increased with readily utilizable substrate (RUS) according to Monod equations, but each with their own characteristic parameter values. The death rate of CB decreased monotonically with substrate concentration, while the death rate ofOBfirst decreased and then increased with substrate concentration. Model parameters were estimated from literature and with an iterative optimization method. Initial biomass and kinetic parameters were lower forOBthan for CB, and fell in the range of values in the literature. The model was validated with an independent data set of bacteria along wheat roots in relatively C-rich soil, so that BGF and initial microbial populations were higher, but other model parameters were the same for both data sets. A satisfactory fit was obtained between experimental and modeled data. This is the first rhizosphere model in which oligotrophic bacteria are taken into account.



    Several microcosm experiments were carried out to investigate the hypothesis that an impulse of fresh substrate into soil would invoke oscillations in bacterial populations (Chapter 5). Soil bacterial populations, mineral nitrogen content, pH, and redox potential (ROP) were monitored daily for one month after incorporation of clover-grass (CG) plant material in soil. Colony-forming units (CFUs) and direct microscopic counts of FDA-stained and FITC-stained bacteria increased immediately after incorporation of the plant material, dropped within 2 days, and fluctuated thereafter. Harmonics analysis demonstrated that there were significant wave-like fluctuations with three or four significant peaks within one month after incorporation of clover-grass material. Ammonium (NH 4+ )concentrations increased from the start of the experiments until nitrification commenced. Nitrate (NO 3−) concentrations dropped immediately after plant incorporation, and then rose monotonically until the end of the experiments. There were no wave-like fluctuations in NH 4+and NO 3−concentrations, so that bacterial fluctuations could not be attributed to alternating mineral N shortage and sufficiency. pH levels rose and declined with NH 4+levels. ROP dropped shortly before NH 4+concentrations rose, and increased before NH 4+concentrations decreased; there were no regular fluctuations in ROP, so that temporary oxygen shortages may not have been responsible for the observed fluctuations in bacterial populations. Thus, for the first time, regular wave-like dynamics were demonstrated for bacterial populations after perturbation by addition of fresh organic matter to soil, and several potential reasons for the death phase of the fluctuations could be excluded from further consideration.



    To elucidate possible reasons for the oscillations in bacterial populations, potential interactions with populations of bacterial predators, in particular bacterial-feeding nematodes (BFN), were investigated (Chapter 6). In two microcosm experiments, soil bacteria (CFU's and microscopic counts of stained bacteria) and nematode populations in 22 families were monitored daily for 25 or 30 days after incorporation of clover+grass (CG) plant material into soil. Soil bacterial populations fluctuated significantly after incorporation of the plant material with 2 peaks within the first week and 3 or 4 smaller peaks thereafter. Total nematodes and BFN populations started to increase in the course of the second week after CG incorporation, but the proportion of BFN increased within one week. Inactive juvenile BFN (dauerlarvae) seemed to be activated after two days (as the percentage of Rhabditidae increased and dauerlarvae decreased), followed by step-wise increases in dauerlarvae every four days, indicating that there was a new generation every four days. There were significant wave-like fluctuations in daily population changes of BFN, but not in total nematode communities, over the duration of these experiments. These fluctuations had similar periods (5 days) as those of bacterial populations, but were shifted about 3 days relatively to the bacterial fluctuations.



    In another microcosm experiment, dynamics of bacterial populations were monitored in response to gamma-irradiated plant material added to gamma-irradiated soil mixed with filtered bacterial suspensions and to non-irradiated soil. Gamma-irradiation of soil significantly increased the periods and amplitudes of bacterial oscillations compared to untreated field soil. Nematode populations were decimated in gamma-irradiated soils, but a small number of protozoa were accidentally introduced in the irradiated soil, and may have been partially responsible for the delayed regulation of bacterial growth. We conclude that fluctuations in bacterial populations were not directly related to similar fluctuations in populations of BFN, as expected from classical Lotka-Volterra equations for predator-prey relationships, but were related to changes in growth rates of BFN. An alternation in active and inactive stages in a synchronized predator community after a disturbance could allow periods of bacterial growth alternated with periods of death. Fluctuations in bacterial populations were dampened after a much longer period when the soil fauna was largely eliminated.



    Findings of regular oscillations in bacterial populations and in the rate of change in numbers of bacterial predators after addition of fresh organic matter to soil stimulated the development of a simulation model to investigate potential mechanisms of those oscillations, and whether they were initiated by bacteria- substrate interactions or predatory regulation of bacteria (Chapter 7). The model could also be used to investigate mineral nitrogen release during short-term organic matter decomposition. A substrate-based food web model was constructed with 3 plant residue and 5 soil organic matter compartments, 3 trophic groups of bacteria (copiotrophic, oligotrophic and hydrolytic), and two predatory groups (BFN and protozoa). Both carbon and nitrogen flows were modeled. Fluctuations in microbial populations in soil after plant residue incorporation could be reproduced with and without participation of predators. The first two peaks in bacterial numbers were mainly related to bacteria-substrate interactions, while predators (particularly protozoa) influenced bacterial dynamics during later stages of bacterial community development. Oligotrophic bacteria had a stabilizing effect on fluctuations of other trophic groups, and were the main source of nutrients for predators. A peak in soil ammonium occurred within one week after residue incorporation. Nitrate increased sigmoidally after a short lag phase. The final nitrate concentration was primarily determined by bacterial dynamics and to a lesser extent by protozoa and nematodes. This model emphasized the importance of substrate-consumer relations for regulation of populations at different trophic levels and nutrient release from fresh organic matter added to soil.



    This research has given insight in potential mechanisms underlying oscillations in populations of soil bacteria and their predators after a disturbance. Despite the advances achieved in this thesis, there are still some problems to be solved. Precise regulation of substrate-consumer interactions and mechanisms that initiate growth and death cycles of soil bacteria have to be investigated in detail. Nevertheless, the "BACWAVE-WEB" model has good potential to predict responses of microbial communities to a disturbance, which could be used to characterize soil health. The model could be expanded to include denitrification and nitrate leaching, so that the extent of N losses after soil disturbance could be predicted.
    Voedselecologie van de gewone en grijze zeehond in de Nederlandse kustwateren; I onderzoek naar de voedselecologie van de gewone zeehond; II literatuurstudie naar het dieet van de grijze zeehond
    Brasseur, S.M.J.M. ; Tulp, I.Y.M. ; Reijnders, P.J.H. ; Smit, C.J. ; Dijkman, E.M. ; Cremer, J.S.M. ; Kotterman, M.J.J. ; Meesters, H.W.G. - \ 2004
    Wageningen : Alterra (Alterra-rapport 905) - 116
    phoca vitulina - halichoerus grypus - foerageren - voedingsgedrag - vis - bevolkingsspreiding - nederland - zeehonden - waddenzee - phoca vitulina - halichoerus grypus - foraging - feeding behaviour - fish - population distribution - netherlands - seals - wadden sea
    Over het dieet en het foerageergedrag van zeehonden in de Nederlandse kustwateren is weinig bekend. Dit rapport beschrijft de eerste fase van een project naar voedselecologie van gewone en grijze zeehonden. Deel I beschrijft het onderzoek naar de gewone zeehond. Hierbij werden dieren gezenderd en onderzocht of de zeehondenverspreiding mogelijk overlap vertoont met visverspreiding. Hiervoor werden zowel visgegevens binnen dit project verzameld als bestaande data gebruikt. Er werd geen positieve relatie gevonden. In fase 2 zal worden onderzocht waarom. Daarnaast werden methodes om de prooikeuze van de dieren te bepalen getest. Deze zullen tijdens fase 2 worden toegepast. Deel II beschrijft een literatuuronderzoek naar het dieet van grijze zeehonden. Dit omschrijft vooral onderzoek aan de hand van maaginhoud- en faecesanalyse. Hieruit blijkt dat de dieren zowel binnen de Noorzee als elders, zeer gevarieerd foerageren. In het Noordzeegebied (vooral rond de Britse eilanden) blijkt zandspiering een van de meest voorkomende prooien.
    Geslachtsafhankelijke dispersie bij boommarters Martes martes in Midden- en Noord-Nederland
    Broekhuizen, S. ; Müskens, G.J.D.M. - \ 2000
    Lutra 43 (2000). - ISSN 0024-7634 - p. 109 - 117.
    martes - martes martes - populatiedynamica - veranderingen in de bevolking - populatie-ecologie - bevolkingsspreiding - nederland - populatiebiologie - population dynamics - population change - population ecology - population distribution - netherlands - population biology
    30 in het verkeer verongelukte boommarters werden onderzocht op geslacht, leeftijd en de afstand tot hun voortplantingsgebieden
    Utilization of rural and suburban habitat by pine marten Martes martes and beech marten M. foina: species-related potential and restrictions for adaptation
    Broekhuizen, S. ; Müskens, G.J.D.M. - \ 2000
    Lutra 43 (2000). - ISSN 0024-7634 - p. 223 - 227.
    martes - martes martes - martes foina - populatiedynamica - populatie-ecologie - bevolkingsspreiding - centraal-europa - west-europa - populatiebiologie - martes - martes martes - martes foina - population dynamics - population ecology - population distribution - central europe - western europe - population biology
    Bestudering van de boom- en steenmarter in Centraal- en West-Europa, die hier niet alleen een grote overlap in verspreiding vertonen, maar ook in het terreingebruik van beide
    Opmerkelijke omzwerving van een boommartermannetje Martes martes
    Broekhuizen, S. ; Dijkstra, V.A.A. ; Müskens, G.J.D.M. - \ 2000
    Lutra 43 (2000). - ISSN 0024-7634 - p. 119 - 123.
    martes - martes martes - populatiedynamica - bevolkingsspreiding - mannelijke dieren - diergedrag - populatiebiologie - gelderland - martes - martes martes - population dynamics - population distribution - animal behaviour - male animals - population biology - gelderland
    De omzwerving van een boommartermannetje tussen Eerbeek en Arnhem
    Vormen de lokale Nederlandse populaties van de boommarter Martes martes een metapopulatie?; mogelijkheden voor moleculair DNA-onderzoek
    Jansman, H.A.H. ; Broekhuizen, S. - \ 2000
    Lutra 43 (2000). - ISSN 0024-7634 - p. 101 - 107.
    martes - martes martes - populaties - populatiedynamica - veranderingen in de bevolking - populatie-ecologie - populatiegenetica - moleculaire genetica - dna - nederland - bevolkingsspreiding - populatiebiologie - populations - population dynamics - population distribution - population change - population ecology - population genetics - molecular genetics - netherlands - population biology
    De laatste 20 jaar is regelmatig voortplanting van de boommarter vastgesteld in 3 gebieden in Nederland. De vraag is of er voldoende genetische uitwisseling tussen de dieren in deze 3 gebieden optreedt. Moleculaire technieken zouden gebruikt kunnen worden om de genetische samenhang van de Nederlandse boommarters na te gaan
    Voorkomen van de boommarter Martes martes in Vlaanderen en het zuiden van Nederland
    Berge, K. van den; Broekhuizen, S. ; Müskens, G.J.D.M. - \ 2000
    Lutra 43 (2000). - ISSN 0024-7634 - p. 125 - 136.
    martes - martes martes - populatiedynamica - populatie-ecologie - bevolkingsspreiding - belgië - nederland - populatiebiologie - population dynamics - population ecology - population distribution - belgium - netherlands - population biology
    Een overzicht van boommartermeldingen
    Development and application of spatial and temporal statistical methods for unbiased wildlife sampling
    Khaemba, W.M. - \ 2000
    Agricultural University. Promotor(en): D. Rasch; A. Stein; J. de Leeuw. - S.l. : S.n. - ISBN 9789058082800 - 148
    gegevens verzamelen - bemonsteren - populatiedynamica - bevolkingsspreiding - populatiedichtheid - wildbeheer - wild - ecologie - gemeenschapsecologie - populatie-ecologie - hulpbronnenbeheer - kenya - data collection - sampling - population dynamics - population distribution - population density - wildlife management - wildlife - ecology - community ecology - population ecology - resource management - kenya

    Current methods of obtaining information on wildlife populations are based on monitoring programmes using periodic surveys. In most cases aerial techniques are applied. Reported numbers are, however, often biased and imprecise, making it difficult to use this information for management purposes. This thesis develops suitable statistical procedures to improve sampling of wildlife populations. It investigates survey and analysis procedures and proposes improvements and modifications to existing methods. Data analysed in the study originate two study areas in Kenya: Masai Mara National Reserve and Laikipia ecosystem.

    Chapter 1 gives a general introduction to the thesis. It formulates the motivation, objectives and scope of the research.

    Chapter 2 investigates different current sampling designs in aerial surveys, with particular focus on systematic and stratified random sampling. Sampling error is a major cause of biased and imprecise estimates of population parameters. Occurrence of several wildlife species in herds violates common assumptions in current sampling methods. This chapter investigates and discusses advantages and disadvantages of two common sampling designs in wildlife surveys: simple random sampling and a modified systematic sampling design known as systematic reconnaissance flights (SRF). It proposes an adaptive sampling design as an alternative that takes clustering of wildlife populations into account and uses criteria on observed animal counts to maximise sampling information. For such populations, the adaptive design is found to be more efficient than the common designs, showing a decrease in the standard error of up to 37%. The comparison focuses on three animal species of varying social behaviour: the elephant ( Loxodonta africana ), kongoni ( Alcelaphus buselaphus ) and wildebeest ( Connochaetes taurimus ).

    Chapter 3 integrates generalised linear modelling with geographic information systems to model abundance and distribution of wildlife in space and time. The chapter focuses on the distribution of elephant during nine successive surveys. It analyses their temporal and spatial distribution and relates these to 12 environmental variables using generalised linear modelling. A principal component analysis identifies five principle components, thereby reducing dimensionality in the data. The number of variables explaining elephant abundance is subject to large variations during successive surveys with a minimum of four and maximum of eight variables. In general, variables related to the protected reserve have more influence on elephant abundance. This chapter also develops a simple distance measure to calculate spatial correlation for wildlife data obtained through aerial surveys by quantifying clustering for different animal species. The procedure is illustrated by data on elephant, kongoni, wildebeest and zebra ( Equus burchelli ). The measure captures clustering in the wildebeest and zebra, which have over 20 times more observations within short distances compared to the other two species.

    Chapter 4 introduces more modern statistical procedures and applies them for better management of wildlife by addressing three key issues: determination of abundance, modelling of animal distributions and variability of diversity in both space and time. Prior information is incorporated in Markov Chain Monte Carlo (MCMC) methods and used to improve estimates of abundance. The new abundance estimates are up to 35% more accurate when compared to those obtained by the common Jolly II method. Modelling distribution is improved by developing a simple space-time procedure within a geographical information system, which includes modelling of autocorrelation in wildlife counts. Significant temporal changes in spatial patterns are found from a space-time analysis of elephant counts over a 20-year period, with strong interactions over 5 km and 6 months space and time separations, respectively. Spatial dependence is found to account for most variation when modelling species distribution. The chapter further proposes a diversity index suitable for monitoring changes in trend of large herbivores and based on transect data. The index is sensitive to both high abundance and species richness and is able to capture year to year variation. It indicates an overall marginal decrease in large herbivore diversity for in the Masai Mara ecosystem. The diversity index is easy be compute, thereby providing a handy tool for rapid decision making.

    Wildlife populations exhibit clustering in their distributions that is difficult to assess quantitatively by analysing transect data obtained from aerial surveys. Chapter 5 looks at this issue and analyses different clustering behaviour and characterises them using spatial point patterns analysis. This is made possible by the availability of a detailed data set, which gives geographic positions of each observed group of animals, leading to data that is amenable to spatial point pattern analysis. Nearest neighbour distance measures like the G -statistic and K -function are used to classify observed patterns as clustered, regular or completely random to correspond to three types of social behaviour, i.e. animals found in large herds, animals found in small to medium herds and solitary animals. Independence between species is tested using a multivariate extension of the K -function. Results show that spatial point patterns from Thomson's gazelle ( Gazellethomsoni ) and impala ( Aepyceros melampus ) come from strongly clustered populations. Clustering is explained for different wildlife species by relating observed patterns to environmental factors like vegetation type. This chapter demonstrates spatial point pattern analysis to be useful in determining and confirming species distribution patterns.

    In chapter 6 once more takes advantage of the detailed data set to develop a procedure that combines statistical simulation techniques and GIS to compare performance of the two common sampling designs, random and systematic, to the adaptive design. The intensive simulation in a GIS compares distribution, sampling and estimation of abundance. The chapter further assesses impact of sampling designs and intensities on estimates of population parameters from the three designs. Performance is compared by means of the root mean square errors at three increasing sampling intensities. Results show an increase in precision of estimates with increasing sampling intensity, while no significant differences are observed between estimates obtained with the two common sampling designs. The study demonstrates an increase in precision for the adaptive design, thereby stressing the importance of using such designs when sampling clustered populations.

    A brief outline is given in chapter 7 to aid a wildlife manager choose between different spatio-temporal techniques and other statistical methods introduced in earlier chapters of the thesis. This short chapter describes different scenarios encountered when making decisions related to the statistical aspects of wildlife management. This is made relevant by the fact that more and more data are collected in space and time and their proper analysis requires appropriate statistical attention. Selection of the right design and analysis method can result in significant savings in cost.

    In summary, this research shows that ecology can largely benefit from application of appropriate statistical techniques. In particular, estimation of population parameters like population size needs sound sampling strategies, while assumptions for each sampling design need to be carefully studied. Use of detailed data proved to be an important improvement in understanding spatial distribution of wildlife. This study suggests that it is better to first model spatial and temporal dependence, which is known to exist for many biological populations, before carrying out more detailed analysis. In general, this thesis shows that several existing techniques useful for studying dynamic populations can be extended and improved to provide tools that improve the information obtained from wildlife surveys.

    In conclusion, the following are main findings of this research:

    • An adaptive sampling strategy as presented in this thesis is an extension to current sampling strategies that allows to sample clustered wildlife populations.
    • Modelling of spatial dependence for individual wildlife species improves estimation of wildlife abundance.
    • Modelling of spatial distributions of wildlife benefits from a further integration of statistical techniques in geographical information systems.
    • An extension of current statistical methods with procedures to analyse spatio-temporal data allows assessing changes in wildlife populations in space and time.
    • A simple diversity index as developed in this study shows a marginal decrease in diversity of large herbivores in the Masai Mara ecosystem.
    • Data that are currently being collected by aerial transects are usually not sufficient for a rigorous statistical analysis. A higher resolution, in particular recording of individual animal locations, is necessary to model spatial distributions of wildlife using spatial point pattern analysis. If a spatial point pattern analysis is carried out, detailed information about the ecology of different species becomes available.
    De waardij van eene vroege opleiding : een onderzoek naar de implicaties van het alfabetisme op het leven van inwoners van Eindhoven en omliggende gemeenten, 1800 - 1920
    Boonstra, O.W.A. - \ 1993
    Agricultural University. Promotor(en): A.M. van der Woude. - S.l. : Boonstra - 465
    onderwijs - samenleving - bevolkingsstructuur - bevolkingsspreiding - statistiek - geschiedenis - migratie - nederland - noord-brabant - cum laude - education - society - population structure - population distribution - statistics - history - migration - netherlands - noord-brabant

    In this study, research has been done into the way literates and illiterates were able to cope with the modernisation process that took place in the Netherlands during the second half of the nineteenth century. Assuming that people who had learned to read and write were better equipped to face modernisation and more eager to go along with it, the question was raised whether literates would show more signs of modern behaviour than illiterates. Research was concentrated in a region around Eindhoven, situated in the southeastern part of the Netherlands. This region was selected because, at that time, Eindhoven started to change from a small a small market town into a industrial city, while the number of illiterates still was considerably large. The analyses showed that although literates and illiterates experienced a same amount of social mobility , illiterates were forced much more to look for another profession, whereas literates moved more freely. It also became apparent that literates were more willing to migrate long distance in order to find a new job. Finally, literates showed more signs of modern demographic behaviour than illiterates. Therefore, it could be concluded that literacy really was a vehicle towards modern behaviour in a modernising society.

    Kleine kernen in de toekomst: groei of stagnatie?
    Groot, J.P. - \ 1982
    De Europese gemeente (1982). - ISSN 0166-4743
    migratie - nederland - ruimtelijke ordening - bevolkingsspreiding - bevolkingsstructuur - nederzetting - statistiek - steden - migration - netherlands - physical planning - population distribution - population structure - settlement - statistics - towns
    Geconcludeerd wordt, dat de kleine kernen ook de komende jaren nog een voortzetting van de groei tegemoet kunnen zien. Veel stedelingen zullen in de toekomst nog de behoefte hebben om in een landelijke omgeving te wonen.
    Enkele multicriteria methoden voor plaatskeuzeproblemen met een toepassing voor een bos in de Lopikerwaard
    Damen, J.C.G. - \ 1974
    Wageningen : ICW (Nota / Instituut voor Cultuurtechniek en Waterhuishouding no. 803) - 29
    ruimtelijke ordening - bevolkingsspreiding - populatiedichtheid - vestigingspatronen - bevolkingsdruk - bosbouw - landgebruik - pachtstelsel - bebossing - besluitvorming - bedrijfsvoering - operationeel onderzoek - simulatie - werkschema - lineair programmeren - nederland - utrecht - lopikerwaard - physical planning - population distribution - population density - settlement patterns - population pressure - forestry - land use - tenure systems - afforestation - decision making - management - operations research - simulation - work flow - linear programming - netherlands - utrecht - lopikerwaard
    Aantal werkende mensen in de landbouw in de verschillende EEG-landen, Groot-Brittannie en Oostenrijk
    Anonymous, - \ 1971
    Wageningen : [s.n.] (Literatuurlijst / Centrum voor landbouwpublikaties en landbouwdocumentatie no. 3293)
    bevolkingsstructuur - bevolkingsspreiding - statistiek - arbeidsmarkt - werkgelegenheid - landbouw - bibliografieën - population structure - population distribution - statistics - labour market - employment - agriculture - bibliographies
    De toekomstige ontwikkeling van de mannelijke beroepsbevolking en van de werkgelegenheid in de land - en tuinbouw in het Noorden
    Perdok, B.H. ; Veer, J. de; Willemsen, A. - \ 1970
    Den Haag : [s.n.] (Streekonderzoek, Bedrijfseconomisch onderzoek, Landbouw-economisch instituut LEI Afd. 2-3, no. 1) - 56
    bevolkingsstructuur - bevolkingsspreiding - statistiek - arbeidsmarkt - werkgelegenheid - agrarische bedrijfsvoering - landbouw - tuinbouw - productiviteit - bedrijfsvoering - Nederland - population structure - population distribution - statistics - labour market - employment - farm management - agriculture - horticulture - productivity - management - Netherlands
    Bibliography land settlement : a survey of the literature on colonization problems and planological aspects in land development projects
    Brouwn, A.E. - \ 1960
    Wageningen : International Institute for Land Reclamation and Improvement (Bibliography / International Institute for Land Reclamation and Improvement no. 2)
    landbouw - bibliografieën - kolonisatie - migratie - ruimtelijke ordening - populatiedichtheid - bevolkingsspreiding - bevolkingsdruk - vestigingspatronen - agriculture - bibliographies - colonization - migration - physical planning - population density - population distribution - population pressure - settlement patterns
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