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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    Marteloscopen – studiemateriaal voor de praktijk
    Ouden, J. den - \ 2016
    Vakblad Natuur Bos Landschap 13 (2016)121. - ISSN 1572-7610 - p. 28 - 29.
    bosbeheer - dunnen - proefvelden - bossen - experimentele bossen - bosbouwkundige handelingen - forest administration - thinning - experimental plots - forests - experimental forests - forestry practices
    De afgelopen jaren zijn op diverse plekken in Nederland bossen ingericht als marteloscoop. De naam “marteloscoop” is afgeleid van het Franse martelage = hameren of blessen, en –scoop = kijken, onderzoeken. De marteloscoop “Oostereng” is officieel in gebruik genomen tijdens de jubileumbijeenkomst van Pro Silva Nederland op 8 oktober 2015. Het betreft een 0.5 ha grote douglasopstand uit 1961, waar in totaal 12 groepen een dunning hebben gesimuleerd. De algemene dunningsinstructie luidde: “Zet een dunning uit waarmee de houtteeltkundige waarde van de opstand zoveel mogelijk verhoogd wordt.”
    Reshaping institutions : bricolage processes in smallholder forestry in the Amazon
    Koning, J. de - \ 2011
    Wageningen University. Promotor(en): Bas Arts, co-promotor(en): Freerk Wiersum. - [S.l. : S.n. - ISBN 9789085856979 - 268
    tropische bossen - bolivia - amazonia - governance - bosbezit - bosbouwkundige handelingen - besluitvorming - plattelandsgemeenschappen - niet-gouvernementele organisaties - instellingen - bosbeleid - tropical forests - bolivia - amazonia - governance - forest ownership - forestry practices - decision making - rural communities - non-governmental organizations - institutions - forest policy
    This thesis aims at identifying the different kinds of institutional influences on forest practices of small farmers in the Amazon region of Ecuador and Bolivia and how small farmers respond to them. It departs from the perspective that institutions affecting forest practices are subject to processes of institutional bricolage in which small farmers construct their own institutional frameworks by aggregating, altering, or articulating elements of existing disparate institutions. This research demonstrates that institutions, whether introduced by government, NGO, or already existing, are subject to processes of institutional bricolage that can be either conscious and strategic of nature or less conscious and unintentional.
    Zelfregulerende bossen; een modelstudie naar effecten van "niets doen" en actief beheer op ontwikkelingen in bosstructuur
    Schelhaas, M.J. ; Wijdeven, S.M.J. ; Werf, B.W. van der - \ 2005
    Wageningen : Alterra (Alterra-rapport 1270) - 43
    bosbedrijfsvoering - bosbouwkundige handelingen - houtteelt - biodiversiteit - opstandsontwikkeling - opstandsstructuur - bossen - modellen - forest management - forestry practices - silviculture - biodiversity - stand development - stand structure - forests - models
    In deze modelstudie worden de effecten van `niets doen¿ en actief beheer onderzocht op de bosontwikkeling en structuurvariatie. Hiervoor is een model verder ontwikkeld en zijn koppelingen gelegd met monitoringsdatabestanden en analyse- en visualisatietechnieken. Simulatieresultaten dienen voorzichtig geïnterpreteerd te worden door beperkingen in het model. Enkele mogelijke hypotheses die uit de simulaties naar voren komen zijn onder ander dat de variatie fluctueert in de tijd, dat op middellange termijn er een grotere structuurvariatie tot stand komt bij beheer dan bij `niets doen¿ en dat bijvoorbeeld het effect van storm de verschillende beheerscenario¿s kan overtreffen
    Gezond werk in het groen; onderzoek naar de inzet van cliënten uit de zorg bij het beheer van bos, natuur en landschap
    Oosterbaan, A. ; Blitterswijk, H. van; Vries, S. de - \ 2005
    Wageningen : Alterra (Alterra-rapport 1253) - 41
    geestelijke gezondheid - geestelijke stoornissen - psychiatrische voorzieningen - natuurbescherming - gezondheidszorg - vegetatiebeheer - bosbouwkundige handelingen - organisaties - druggebruikers - nederland - arbeid (werk) - sociale zorg - mental health - mental disorders - psychiatric services - nature conservation - health care - vegetation management - forestry practices - organizations - drug users - netherlands - labour - social care
    In 2005 is een inventariserend onderzoek uitgevoerd naar de inzet van cliënten uit de zorg bij bos-, natuur- en landschapsbeheerorganisaties. In vrijwel alle regio’s van de grote beheerorganisaties worden op de een of andere wijze mensen met gezondheids- of andere problemen ingezet bij werkzaamheden in natuur en landschap. De meeste regio’s geven aantallen van 1-10 per jaar aan, maar bijna een kwart 30-100. Geschat wordt dat de genoemde beheerorganisaties gezamenlijk 1500-2000 mensen met gezondheidsproblemen laten werken in het groen. Hierbij gaat het vrijwel altijd om uitvoerend buitenwerk (bomen zagen, opsnoeien, knotten e.d.). De belangrijkste groepen zijn psychiatrische patiënten, (ex)verslaafden en verstandelijk gehandicapten. Voor de beheerorganisaties spelen ideële overwegingen een belangrijke rol. De begeleiding van de cliënten en ook de financiering van het werk varieert: soms door de natuur-, bos- of landschap¬organisatie, soms door de gezondheidsorganisatie, soms gecombineerd. Veel genoemde factoren, die pleiten voor werken in bos, natuur en landschap zijn het buiten zijn, de buitenlucht, werken in de natuur en fysieke inspanning. Naar de werkelijke effecten is meer onderzoek gewenst
    Houtkwaliteit en bosbeheer; beslist meer aandacht waard (deel 1)
    Wijers, R. ; Oosterbaan, A. - \ 2005
    Vakblad Natuur Bos Landschap 2 (2005)8. - ISSN 1572-7610 - p. 12 - 15.
    bosbeheer - houteigenschappen - bosbouwkundige handelingen - hout - kwaliteit - forestry practices - forest administration - wood properties - wood - quality
    Dit artikel gaat in op verschillende aspecten van houtkwaliteit in relatie tot het gevoerde bosbeheer. Het omvat de gehele inlandse bosbouw en houtverwerkingsketen
    Wanneer is goed veilig?
    Niemeijer, C.M. ; Oosterbaan, A. - \ 2004
    Vakblad Natuur Bos Landschap 1 (2004)6. - ISSN 1572-7610 - p. 26 - 27.
    bosbouw - bosbomen - bosbouwkundige handelingen - onderhoud - gereedschappen - openbaar groen - bosopstanden - forestry - forest trees - forestry practices - maintenance - tools - public green areas - forest stands
    In de jaren negentig bleek de bosbouw- en groenvoorzieningsector een van de onveiligste sectoren te zijn in Nederland. Verbetering van de werkomstandigheden was dus hard nodig. Hierbij is de beschikbaarheid van goedgekeurde apparatuur en middelen een belangrijk aandachtspunt. Logo's (als kwaliteitsaanduiding) kunnen de aspirant-koper helpen om iets goeds te kopen
    Bedrijfsdiagnose bosbedrijven; een methode voor bedrijfsonderzoek
    Raffe, J.K. van; Jong, J.J. de; Wolf, R.J.A.M. ; Schrijver, R.A.M. - \ 2002
    Wageningen : Alterra (Alterra-rapport 440) - 137
    bosbouw - ondernemingen - bosbedrijfsvoering - operationeel onderzoek - kosten-batenanalyse - bosbouweconomie - bosbouwkundige handelingen - nederland - bedrijfseconomie - forestry - enterprises - forest management - operations research - cost benefit analysis - forest economics - forestry practices - netherlands
    In dit rapport wordt een methode van bedrijfsonderzoek beschreven waarmee het bedrijfsmatig handelen van bosbedrijven kan worden vastgesteld. Op basis van de methode is een computerprogramma (een prototype) gemaakt dat in de praktijk is getoetst. Met de methode en de software moeten boseigenaren gestimuleerd en ondersteund worden tot een meer bedrijfsmatige manier van werken.
    Bedrijfsdiagnose bosbedrijven; een methode voor bedrijfsonderzoek
    Jong, J.J. de; Raffe, J.K. van - \ 2001
    Wageningen : Alterra (Alterra-rapport 247) - 83
    bosbouw - ondernemingen - bosbedrijfsvoering - operationeel onderzoek - kosten-batenanalyse - bosbouweconomie - bosbouwkundige handelingen - nederland - forestry - enterprises - forest management - operations research - cost benefit analysis - forest economics - forestry practices - netherlands
    In dit rapport wordt een methode van bedrijfsonderzoek beschreven waarmee het bedrijfsmatig handelen van bosbedrijven kan worden geanalyseerd. Dit rapport moet de basis zijn voor een computerprogramma dat bosbedrijven en hun adviseurs kunnen gebruiken. Achterliggend doel is bosbedrijven een hulpmiddel te bieden waarmee ze gestimuleerd worden tot een meer bedrijfsmatige manier van werken.
    Uitwerking bedrijfsplanning geïntegreerd bosbeheer voor gemeente Someren; deel 5 werkplan 2000
    Raffe, J.K. van; Wolf, R.J.A.M. - \ 2000
    Wageningen : Alterra (Alterra-rapport 52.5) - 39
    bosbedrijfsvoering - doelstellingenmanagement - planning - bosbouw - bosbouwkundige handelingen - economie - natuurbescherming - nederland - experimentele bossen - bedrijfsinformatiesystemen - geïntegreerd bosbeheer - forest management - management by objectives - planning - forestry - forestry practices - economics - nature conservation - netherlands - experimental forests - management information systems - integrated forest management
    In het voorbeeldbedrijf Someren wordt getoond hoe bos beheerd kan worden volgens de principes van geontegreerd bosbeheer. Daarbij wordt ook veel aandacht besteed aan de bedrijfsvoering die samengaat met de toepassing van geontegreerd bosbeheer. Voor dit doel is een aantal voorbeeldplannen opgesteld (beheervisie, beheerplan en werkplan). Deze plannen, die zijn opgesteld op basis van een door Alterra ontwikkelde planningssystematiek, zijn in dit rapport samengebracht.
    Over planning bij geïntegreerd bosbeheer; naar aanleiding van een workshop op de manifestatie Bos & Bomen 2000
    Wolf, R.J.A.M. ; Raffe, J.K. van - \ 2000
    Nederlands Bosbouwtijdschrift 72 (2000)4. - ISSN 0028-2057 - p. 129 - 132.
    bosbeheer - bosbedrijfsvoering - bosbouw - bedrijfsvoering - doelstellingenmanagement - natuurbescherming - bosbouwkundige handelingen - bosinventarisaties - experimentele bossen - noord-brabant - geïntegreerd bosbeheer - forest administration - forest management - forestry - management - management by objectives - nature conservation - forestry practices - forest inventories - experimental forests - noord-brabant - integrated forest management
    Door Alterra en Eelerwoude Ingenieursbureau is een planningsmethodiek opgesteld voor geïntegreerd bosbeheer en uitgewerkt voor de gemeente Someren (Noord-Brabant). Een aantal aspecten worden besproken: schaal (planningseenheden); zoneren (natuur, houtproductie, recreatie); doelformulering (terreindoelen); maatregelcriteria (voor het uitvoeren van beheersmaatregelen); bosinventarisatie (moment, soort inventarisatie, inventarisatie-eenheid); relatie beheersplanning en Programma Beheer
    Behoud van structuurvariatie en menging in het Zeisterbosch; Pro Silva excursie oktober 1999
    Wolf, R.J.A.M. ; Houtzagers, M.R. - \ 2000
    Nederlands Bosbouwtijdschrift 72 (2000)1. - ISSN 0028-2057 - p. 13 - 15.
    bosbedrijfsvoering - bosbouwkundige handelingen - bosbouw - gemeenschapsbosbouw - houtteelt - houtteeltkundige systemen - bossen - mengsels - opstandsontwikkeling - opstandskenmerken - opstandsstructuur - variatie - ruimtelijke variatie - verjonging - natuurlijke verjonging - bosopstanden - gemengde opstanden - natuurlijke opstanden - utrecht - forest management - forestry practices - forestry - community forestry - silviculture - silvicultural systems - forests - mixtures - stand development - stand characteristics - stand structure - variation - spatial variation - regeneration - natural regeneration - forest stands - mixed stands - natural stands - utrecht
    Hoe behoud je structuurvariatie en menging door kleinschalige ingrepen en natuurlijke verjonging in een oud en zeer gevarieerd bos. Verschillende soorten opstanden in het Zeisterbosch werden bezocht en bediscussieerd
    Modellering van bosbeheer in SUMO
    Wamelink, G.W.W. ; Wegman, R. ; Slim, P.A. ; Dobben, H.F. van - \ 2000
    Wageningen : Alterra (Alterra-rapport 66)
    bosbedrijfsvoering - bosbouwkundige handelingen - biomassa - bossen - velling - dunnen - struiken - simulatie - modellen - nederland - onderlaag - forest management - forestry practices - biomass - forests - felling - thinning - shrubs - simulation - models - netherlands - understorey
    In het vegetatievoorspellingsmodel SUMO is de beheermodule uitgebreid met twee vormen van bosbeheer: regulier bosbeheer en hakhoutbeheer. Het regulier bosbeheer bestaat uit elke vijf jaar dunnen en kaalkap aan het eind van de omloopperiode. De omloopperiode en het dunningspercentage zijn per boomsoort verschillend. De effecten van het beheer zijn een variërende stikstofbeschikbaarheid (gering na dunnen en groot na kappen) en een betere simulatie van de biomassa: teruggang in biomassa van de bomen na dunnen, en na kappen een enorme toename van de biomassa van de kruiden. Ook het hakhoutbeheer (voor eiken-, wilgen- en elzenhakhout) heeft veel invloed op de biomassa, al is verder onderzoek naar de biomassaverdeling over de functionele typen noodzakelijk. Toevoeging van beide beheersvormen geeft een duidelijke verbetering te zien van de simulatie van de bosontwikkeling.
    Effecten van een veranderend bosbeheer op de houtkwaliteit; een methode om de invloed van veranderingen in het beheer op de houtkwaliteit te bekijken, toegepast op douglas
    Wijk, M.N. van; Schelhaas, M.J. ; Edelenbosch, N.H. - \ 1999
    Wageningen : IBN-DLO, Instituut voor Bos- en Natuuronderzoek - 86
    bosbouw - bomen - bosbedrijfsvoering - bosbouwkundige handelingen - conservering - houteigenschappen - pseudotsuga menziesii - kwaliteit - nederland - forestry - trees - forest management - forestry practices - conservation - wood properties - pseudotsuga menziesii - quality - netherlands
    Kosten en doelrealisatie van bosbeheer
    Raffe, J.K. van; Wieman, E.A.P. - \ 1999
    Nederlands Bosbouwtijdschrift 71 (1999)4. - ISSN 0028-2057 - p. 157 - 159.
    bosbedrijfsvoering - bossen - bosbouw - bosbouwkundige handelingen - onderzoek - onderzoeksprojecten - verjonging - conversie - houtteelt conversie - houtteeltkundige systemen - conservering - natuurbescherming - herstel - biodiversiteit - kosten - kostenanalyse - kosten-batenanalyse - rentabiliteit - rendement - natuur - forest management - forests - forestry - forestry practices - research - research projects - regeneration - conversion - silvicultural conversion - silvicultural systems - conservation - nature conservation - rehabilitation - biodiversity - costs - cost analysis - cost benefit analysis - profitability - returns - nature
    Enkele resultaten van het IBN-DLO onderzoek 'Kosten en doelrealisatie van omvorming naar kleinschalig gestructureerd bos'. Voor een aantal omvormingsscenario's werden de bedrijfseconomische kosten en opbrengsten en de winst (of verlies) aan natuurwaarden bepaald. Verder uitleg over het kennissysteem waar dit onderzoek deel van uitmaakt
    Paalhout uit jonge Robinia beplantingen
    Rots, J. ; Oosterbaan, A. - \ 1999
    Nederlands Bosbouwtijdschrift 71 (1999)4. - ISSN 0028-2057 - p. 176 - 179.
    robinia pseudoacacia - bosbouw - bebossing - houtteelt - bosbouwkundige handelingen - groei - plantenontwikkeling - stamvorm - milieufactoren - palen (poles) - plantmateriaal - oorsprong - plaatsen op afstand - verzorgen van jonge opstanden - robinia pseudoacacia - forestry - afforestation - silviculture - forestry practices - growth - plant development - stem form - environmental factors - poles - planting stock - origin - spacing - tending
    Resultaten van onderzoek naar de groei en het aandeel paalhout van jonge Robinia beplantingen op voormalige landbouwgrond, en de invloed daarop van herkomst, plantafstand en behandeling
    If timber production did not require cutting down trees ... communicating timber management in society
    Schanz, H. - \ 1999
    Nederlands Bosbouwtijdschrift 71 (1999)6. - ISSN 0028-2057 - p. 232 - 236.
    bosbouw - bosbouwkundige handelingen - hout - houtsoorten - productie - bosbedrijfsvoering - samenleving - interacties - public relations - openbare mening - attitudes - communicatie - voorlichting - forestry - forestry practices - wood - timbers - production - forest management - society - interactions - public relations - public opinion - attitudes - communication - extension
    De 'slachthuis-paradox' in de bosbouw; mensen houden van bos en van hout, maar niet van de noodzakelijke tussenstap: houtproductie en houtkap. Mogelijkheden om meer sociale acceptatie te krijgen voor de houtproductie-functie van het bos
    Bosbouw in Canada : aan de vooravond van duurzaam bosbeheer?
    Bartelink, H.H. ; Hees, A.F.M. van; Bos, J.M. van den; Mangelmans, P.J.J. - \ 1999
    Nederlands Bosbouwtijdschrift 71 (1999)3. - ISSN 0028-2057 - p. 119 - 124.
    bossen - bosbouw - bosbouwkundige handelingen - houtteelt - duurzaamheid (sustainability) - bosbeleid - bosbedrijfsvoering - biodiversiteit - brits-columbia - quebec - nova scotia - canada - forests - forestry - forestry practices - silviculture - sustainability - forest policy - forest management - biodiversity - british columbia - quebec - nova scotia - canada
    Bosbouwbeleid en bosbouwpraktijk in British Columbia, Quebec en Nova Scotia. Verslag van een studiereis met aandacht voor certificering, duurzaam beheer, voorlichting, biodiversiteit, recreatie, 'first nations' problematiek, onderzoek, beheer en beleid
    Conservation and utilization of natural resources in the East Usambara forest reserves: conventional views and local perspectives
    Kessy, J.F. - \ 1998
    Wageningen University. Promotor(en): Paul Richards, co-promotor(en): M. Wessel. - [S.l.] : S.n. - ISBN 9789054858096 - 168
    bosbouw - bossen - natuurreservaten - natuurbescherming - bosbouwkundige handelingen - sociale economie - natuurlijke hulpbronnen - landgebruik - pachtstelsel - bebossing - tanzania - bosproducten anders dan hout - nationaal vermogen - forestry - forests - nature reserves - nature conservation - forestry practices - socioeconomics - natural resources - land use - tenure systems - afforestation - tanzania - non-wood forest products - national wealth
    The importance of conserving biological resources and the need for managing these resources for present and future generations has been given much attention internationally in the past three decades. These ideas have been emphasized in key documents such as the Brundtland report as well as in international conventions such as the global convention on biodiversity which followed the Rio meeting in 1992. The challenge in implementing these ideas lies in finding the proper trade-offs between current and future utilization of natural resources. Their success depends very much on the kind of policy reforms undertaken by nations to accommodate both local and international interests. Relevant policy adjustments are rarely observed in developing countries. For example, in Tanzania forest policies of the 1950s and early 1960s are still in use despite the recent developments in thinking about forest conservation issues. Conventional conservation approaches still dominate despite current emphasis on the need to involve all relevant stakeholder groups in preparing forest conservation plans. This approach often neglects the interests and value systems of the different groups of stakeholders with ultimate deleterious impact on forest resources.

    This study was conducted to examine the values, perceptions and actions with respect to forest resources of various stakeholders in the East Usambaras in Tanzania. This forest area has a high degree of species diversity and endemism that is threatened by increasing human pressure on resources. Conceptually the research was based on the appreciation of the existence of varying value systems between different stakeholders in relation to forest resources in the East Usambarasas, e.g. conservationists, estate holders and local villagers. The research focused on the collection of empirical evidence to substantiate the disparity of value systems amongst different stakeholders, and on the analysis of the impact of this disparity and possible modalities for reconsiliation reconciliation he objective of the study study was to investigate the potentials and limitations of involving local communities and other stakeholders in conserving the East Usambara forests, and to propose appropriate development strategies for harnessing such potentials. In order to reach this objective, the nature of various stakeholders' activities in relation to the forests was studied and the impact of such actions on long-term biodiversity conservation prospects in the area was assessed.

    An extensive literature search indicated a variety of arguments concerning the nature and extent of problems in natural resource management and the range of recommended approaches in solving such conservation problems. Different perceptions on fundamental concepts in biodiversity conservation exist; these reflect the diversity of values that individuals and social organizations attach to natural resources. For effective management of conservation areas these perceptions should be reconciled, and global and local interests should be balanced. This indicates the need to assess the significance of indigenous forest management systems and to augment the conventional approach to managing nature reserves with community management of forest resources. These ideas were used to formulate the key concepts and analytical framework for this study.

    The research consisted of the collection of information on both technical and sociological aspects of forestry. Because of this, a variety of research methods were deployed such as participatory rural appraisal, a general questionnaire survey and several more specialized surveys. The specialized surveys consisted of (a) several assessments of the different types forest products collected by local people, (b) a forest survey to ascertain the impact of human activities on the natural forests, and (c) a survey to assess the nature and extent of domestication of forest plants by local people. Additional information was collected through in-depth interviews with key informants, field observations and study of secondary data.

    The research started with a reconnaissance of twenty villages out of the total of fifty-four villages in the East Usambaras. These rapid village appraisals entailed both formal and informal discussions. The investigation aimed to expose the general characteristics of different villages and to provide the basis for selection of case study villages. Six villages were subsequently selected as case study villages representing the various ecological conditions in the area. These included Kisiwani, Mikwinini, Kwamzindawa, Potwe-Ndondondo, Hemsambia and Vuga.

    In all case study villages an open ended questionnaire was administered to solicit data on socio- economic conditions, forest products utilization trends, and local people's perceptions on a variety of conservation and development aspects. In each village a random selection of 20% of the households was made; in total 292 households were surveyed. Also several surveys on the use of forest products were carried out. An investigation of the different building materials of forest origin commonly used by villagers was done in five out of the six case study villages. The species used for building purposes and their quantities were estimated by surveying 41 houses which were under construction. In five villages a study was made of items of forest origin used at household level. In a sample of 10% of the households (135 households) all utensils derived from materials of forest origin were recorded. Also a market survey was carried out to collect information on the nature and amounts of both wood and non-wood forest products which are commercialized. On three markets 16 merchants were interviewed and their supply of products measured. A study was also made about the extent of human disturbance to the forest reserves as a result of forest products collection. The extent of the disturbance resulting was assessed in 150 sample plots of 0. 1 ha in size established at 100 to 200m, 500m and 1000m from the forest edge. In these plots forest characteristics such as species composition, signs of human impact and forest regeneration were recorded. Finally, in three villages a farm survey took place to record the presence and use of plants of forest origin on farmer fields.

    Data analysis was both quantitative and qualitative. The findings from the reconnaissance survey and rural appraisals were analyzed to provide insight for the more detailed surveys which were to follow. Information collected through the questionnaire survey was coded and analyzed with the SPSS statistical program for social sciences. The coding involved structuring the responses from the open- ended questionnaire and assigning them nominal values for analytical purposes. Considering the nature of the study mainly descriptive statistics were used. Data collected from the building materials survey, survey of household used items, market survey, forest sampling and domestication survey were analyzed using the Q&A4 database and Harvard Graphics 3.0 programs. Species names and synonyms were cross-checked using Kewensis database. Content analysis was used to analyze qualitative information from indepth interviews, and participant observations.

    The research findings presented in this book focus on the socio-economic conditions in the area, the values of the forests for local people, the effects of forest utilization, and the need to search for alternatives in managing the forest reserves and conserving their biodiversity.

    In the East Usambara basically three types of (agro)forestry systems are present: natural forests, forest plantations and on-farm tree growing systems. These forests are under the management responsibility of either the state, district or village institutions, estates or private persons. The natural forests are surrounded by a countryside occupied by very heterogenous human population, which is increasing rapidly because of both natural growth and immigration. Both subsistence and commercial agriculture is taking place. Commercial agriculture is dominated by tea and sisal estates, while subsistence agriculture consists of mixed cropping systems on farms of about three hectares in size. Farmers practice shifting cultivation using short fallow periods and local farming techniques. In some cases when shade trees are required such as for the cultivation of cardamom, or when locally- valued trees are present. not all trees are removed. But in general, due to poor soils the agricultural practices are often detrimental to the environment. In addition farmers also cultivate permanent homestead plots. A range of formal and informal institutions governing land use practices were discerned in the area. However, these institutions are not harmoniously organized to pursue conservation initiatives.

    Forests are very valuable to local communities in terms of both cultural and utilitarian benefits. Many different tree products are collected either for household use or sale. Forest plants provide fuelwood (33 species). poles (35 species), withies (32 species), ropes (11 species), foods (28 species), medicines (185 species) and household utensils (83 species). The annual per capita consumption of fuelwood was estimated at 1.7 cubic meters while the annual consumption of forest vegetables was estimated to be about 12 kg per household. The different products are collected either from the forest reserves, estate plantations or privately grown trees; collection in the forest reserves still predominates. Besides these utilitarian functions the local people also value forests for religious (e.g. traditional rainmaking ceremonies) and environmental values. The role of forests for regulating hydrological and micro-climate conditions and its significance for agricultural production are well recognized.

    The management of the forest reserves is still dominated by a conventional conservation approach that tends to alienate communities from conservation areas. Despite conservation regulations, human activities in the forest still continue. Illegal collection of forest products has affected the composition and structure of the forests adversely. The destruction of trees is most intensive near the forest edge, while animal trapping becomes more intensive with increasing distance from the forest edge. The harvesting of forest products by local people has resulted in the reduction of stocking level of trees from the estimated normal tree density of 650 stems/hectare to about 500 stems per hectare. The diameter distribution of trees has also been affected: trees with small diameters dominate close to the forest edge (up to 200m from the forest edge), whereas trees have a larger diameter deeper in the forest. Near the forest edge also many coppiced trees are present: respectively 49% and 42% of all coppiced trees were found in the 100-200m and 200-500m range from the forest edge, against about 9% deeper into the forest. Also the number of dead stumps decreases as the distance from the forest edge increases, but the reverse is the case for debarked trees. Illegal collection of forest products affected both endemic and non-endemic species.

    The local villagers are not just using the forest resources, they have also developed various management practices for the forest resources valued by them. For instance, villagers from Vuga and Hemsambia communally manage about 30 hectares of natural forest in the public lands. This forest was traditionally used for ritual purposes, but had been mismanaged by irresponsible village leaders. To prevent further depletion of this forest, the villagers agreed on a set of rules and regulations governing the utilization of resources in this forest and appointed a forest management committee. These initiatives were complementary to the conservation efforts by the Forest Division in other forest reserves in the area. Another example of local management efforts is the on-farm cultivation of tree species of forest origin for both consumptive and non-consumptive use. Such domestication concerns trees providing food, medicine, construction, lumber and local tools, or providing ecological services such as water conservation, shade and support to crops. About 10% of the domesticated species are endemic or near endemic.

    Although the needs and perceptions of the local farmers and conservationists are not always contradictory, in practice substantial gaps between the values and perceptions of various stakeholders interests in forests exist. Different interest groups have different perceptions of what biodiversity entails and how it should be conserved. Most professionals, donor agents and the educated elite understand and appreciate the importance of biological diversity from ecosystem down to genetic level. Their evaluation of the need for biodiversity conservation tends to focus specifically at ecosystem and species level. But the local people view the importance of the biodiversity of rests in terms the products and services that they can derive from the forests. Both professionals and local people consider the need for intergenerational flow of benefits from forests. However, professional conservationists are predominantly occupied with endangered species, centers of endemism, future prospects of new commercial, e.g. pharmaceutical, products and future use of genetic resources. Whereas local people are considering the livelihood of their descendants in terms of availability of rainfall, traditional medicines, fuelwood and building materials. This contrast in perception on the relevance of biodiversity is illustrated by the fact that conservationists pay more attention to the fact that 25% (about 710 species) of all vascular plant species and 18% (48 species) of all tree species are (near) endemic in the East Usambara, than to the fact that about 350 tree species (of which less than 6% of the endemic species) are used by the local population. Nor do they appreciate the fact that local people have taken conscious efforts to conserve around 100 tree species (of which about 20 endemic species) by cultivating them.

    A third interest group with specific perceptions on -the conservation of the natural resources in the Usambaras consists of the private commercial estates, particularly the tea estates. This interest group focuses specifically on two important forest benefits- rainfall and fuelwood. While rainfall boosts production, fuelwood supplies energy to company boilers. Future management of the forests in the area, as far as this, interest group is concerned, should pay attention to the catchment potential and supply of fuelwood from various sources, including plantations outside the forest reserves.

    Obviously, all three interest groups value the forests, be it for different reasons. Thus, they have at least in common that no group is in favor of forest depletion. The central challenge to the management of the forests is to build cooperative alliances between these groups, taking full account of the different value frameworks they bring to forest conservation. It is only when the specific interests of each group of forest user is considered, that these groups will develop interest in cooperation with the Forest Division in managing the forests. The main weakness of the current forest management is that it provides neither the forum nor the opportunity for different stakeholders to express their interests in relation to the forests. It is only when such a framework for expressing, debating, contesting and resolving differences of interest is in place that each interest group will respect the interest of other groups and develop cooperative norms. The study ends therefore with the outlining of a Stakeholder Reconciliation Model (SRM), which serves to address key issues such as policy formulation, land- use planning, communication and reconciliation of competing stakeholder claims. It is suggested, that this is an essential institutional prerequisite for achieving sustainable conservation of the forest resources in the East Usambaras.

    Vergelijkend onderzoek naar de gebruikswaarde van twaalf Nederlandse en veertien Belgische klonen van populier. Comparative research on characteristics of twelve Dutch and fourteen Belgian poplar clones
    Kranenborg, K.G. ; Vries, S.M.G. de - \ 1998
    Wageningen : IBN-DLO (IBN-rapport 359) - 28
    forestry - trials - hybrids - tree breeding - trees - plant breeding - clones - silviculture - forestry practices - growth - environmental factors - netherlands - belgium - bosbouw - proeven - hybriden - boomveredeling - bomen - plantenveredeling - klonen - houtteelt - bosbouwkundige handelingen - groei - milieufactoren - nederland - belgië
    In voor- of najaar verplanten? Een proef met gewone esdoorn
    Schuring, W. ; Das, C. - \ 1998
    Nederlands Bosbouwtijdschrift 70 (1998)2. - ISSN 0028-2057 - p. 66 - 69.
    bosbouw - beplanten - aanslaan van het gewasbestand - seizoenen - houtteelt - bosbouwkundige handelingen - groei - milieufactoren - forestry - planting - stand establishment - seasons - silviculture - forestry practices - growth - environmental factors
    Conservation and utilization of natural resources in the East Usambara forest reserves: conventional views and local perspectives.
    Kessy, J.F. - \ 1998
    Wageningen : Wageningen Agricultural University (Tropical Resource Management Papers 18) - ISBN 9789054858096 - 168
    bosbouw - bossen - natuurreservaten - natuurbescherming - bosbouwkundige handelingen - sociale economie - natuurlijke hulpbronnen - landgebruik - pachtstelsel - bebossing - tanzania - bosproducten anders dan hout - nationaal vermogen - forestry - forests - nature reserves - nature conservation - forestry practices - socioeconomics - natural resources - land use - tenure systems - afforestation - tanzania - non-wood forest products - national wealth
    Groei en groeiplaats van de zomereik, de wintereik en de Amerikaanse eik in Nederland
    Burg, J. van den - \ 1997
    Wageningen : IBN-DLO - 104
    bosbouw - standplaatsfactoren - bepaling van groeiplaatshoedanigheden - houtteelt - bosbouwkundige handelingen - groei - milieufactoren - bomen - nederland - quercus robur - quercus petraea - quercus rubra - forestry - site factors - site class assessment - silviculture - forestry practices - growth - environmental factors - trees - netherlands - quercus robur - quercus petraea - quercus rubra
    Groei en groeiplaats van de zwarte els en van de witte els in Nederland
    Burg, J. van den - \ 1997
    Wageningen : IBN-DLO - 57
    bosbouw - standplaatsfactoren - bepaling van groeiplaatshoedanigheden - houtteelt - bosbouwkundige handelingen - groei - milieufactoren - bomen - nederland - alnus glutinosa - alnus incana - forestry - site factors - site class assessment - silviculture - forestry practices - growth - environmental factors - trees - netherlands - alnus glutinosa - alnus incana
    Groei en groeiplaats van de beuk in Nederland
    Burg, J. van den - \ 1997
    Wageningen : IBN-DLO - 60
    bosbouw - standplaatsfactoren - bepaling van groeiplaatshoedanigheden - bomen - bodemkarteringen - kaarten - houtteelt - bosbouwkundige handelingen - groei - milieufactoren - nederland - fagus sylvatica - forestry - site factors - site class assessment - trees - soil surveys - maps - silviculture - forestry practices - growth - environmental factors - netherlands - fagus sylvatica
    Groei en groeiplaats van de grove den en de Corsicaanse den in Nederland
    Burg, J. van den - \ 1997
    Wageningen : IBN-DLO - 90
    bosbouw - houtteelt - bosbouwkundige handelingen - groei - milieufactoren - bepaling van groeiplaatshoedanigheden - bomen - nederland - forestry - silviculture - forestry practices - growth - environmental factors - site class assessment - trees - netherlands
    Trends in het ecologisch functioneren van bossen
    Bouwma, I.M. ; Olsthoorn, A.F.M. - \ 1997
    Wageningen : IBN-DLO - 77
    bosbouw - plantensuccessie - periodiciteit - vegetatie - houtteelt - bosbouwkundige handelingen - groei - milieufactoren - bossen - milieubescherming - conservering - plantenecologie - nederland - forestry - plant succession - periodicity - vegetation - silviculture - forestry practices - growth - environmental factors - forests - environmental protection - conservation - plant ecology - netherlands
    Het Europese bos groeit sneller
    Nabuurs, G.J. ; Olsthoorn, A.F.M. ; Dik, E.J. - \ 1997
    Nederlands Bosbouwtijdschrift 69 (1997)1. - ISSN 0028-2057 - p. 24 - 27.
    bosbouw - houtteelt - bosbouwkundige handelingen - groei - milieufactoren - europa - forestry - silviculture - forestry practices - growth - environmental factors - europe
    Eind augustus '96 is in Freiburg het eindresultaat van het project 'Groeitrend in Europese bossen' gepresenteerd. Het boek is een bundeling van 22 case studies in 12 Europese landen naar de ontwikkeling van de groei in de laatste decennia
    Groeiplaatsen als basis voor bostypologie; vaste grond onder de voeten van bosbeheerders
    Wolf, R.J.A.M. ; Dort, K.W. van; Vrielink, J.G. - \ 1996
    Nederlands Bosbouwtijdschrift 68 (1996)5. - ISSN 0028-2057 - p. 177 - 189.
    bosbouw - houtteelt - bosbouwkundige handelingen - groei - milieufactoren - vegetatietypen - bossen - classificatie - bodemkarteringen - kaarten - nederland - forestry - silviculture - forestry practices - growth - environmental factors - vegetation types - forests - classification - soil surveys - maps - netherlands
    Fenologie en groei van bomen in relatie tot klimaatverandering
    Kramer, K. ; Mohren, G.M.J. - \ 1996
    Nederlands Bosbouwtijdschrift 68 (1996)2. - ISSN 0028-2057 - p. 73 - 78.
    bosbouw - klimaatverandering - paleoklimatologie - houtteelt - bosbouwkundige handelingen - groei - milieufactoren - Nederland - forestry - climatic change - palaeoclimatology - silviculture - forestry practices - growth - environmental factors - Netherlands
    Onderzoek naar de groei van tamme kastanje (Castanea sativa) in Nederland
    Oosterbaan, A. - \ 1996
    Bosbouwvoorlichting 35 (1996)2. - ISSN 0166-8986 - p. 18 - 18.
    biomassa - milieufactoren - bosbouw - bosbouwkundige handelingen - groei - houtaanwas - nederland - houtteelt - opstandsontwikkeling - opstandsstructuur - bomen - castanea sativa - biomass - environmental factors - forestry - forestry practices - growth - increment - netherlands - silviculture - stand development - stand structure - trees - castanea sativa
    Samenvatting van IBN-rapport 197
    Changing forest management strategies in Sudan : a challenge for forestry educational systems
    Mahir, S.S. - \ 1996
    Agricultural University. Promotor(en): W. van den Bor; N.G. Röling. - S.l. : Mahir - ISBN 9789054854951 - 263
    bosbouw - bosbedrijfsvoering - theorie - duurzaamheid (sustainability) - opbrengsten - bosbouwkundige handelingen - sociale economie - voorlichting - onderwijs - sociale bosbouw - landgebruik - pachtstelsel - bebossing - inheemse kennis - sociale verandering - sudan - sociale processen - forestry - forest management - theory - sustainability - yields - forestry practices - socioeconomics - extension - education - social forestry - land use - tenure systems - afforestation - indigenous knowledge - social change - sudan - social processes

    This study is an effort to understand the way various categories of social actors go about their interaction with the management of forest resources in Sudan. By providing an overview and description of the motives, perceptions, and management objectives and strategies of social actors, the study tries to contribute towards better understanding of the social, economic and cultural factors influencing the resource management. The specific objectives of this study include:
    (1) Investigation of how social actors interact with forest resources in an era of rapidly changing conditions.
    (2) Get a better understanding of how changes in management objectives and strategies are influencing and are influenced by knowledge processes.
    (3) Analyze present forestry education's curriculum.
    (4) Explore possibilities of incorporating what we learn during the course of this study to propose a model for development of curriculum for forestry education in Sudan.

    This dissertation is written on the basis of empirical data collected from various individuals, groups and institutions involved in forest resources management in Sudan. The field work for the study was carried out mainly in the Central region of Sudan. However, the author's own experiences and those of other officials who worked in other locations, made the scope of the study not limited to geographical boundaries of the region.

    For the data collection, a combination of methodological instruments such as discussions, semi-structured interviews and participant observation, were used iteratively. Besides, taking a social actor as a unit of analysis, the study has used a hybrid of the systems' and the actors' perspectives as the main analytical tool.

    The main findings of this study indicate that:

    First, whereas, a forest is the unit of concern for officials, it is the tree which draws villagers' attention more than the forest as such. However, in general social actors see trees and forests as sources and signs of life. Besides, various actors attach different social, economic and/or cultural meanings to trees/forests. Consequently, they develop varying management objectives and strategies. In this regard, this study shows that similarity between foresters' and villagers' objectives is the exception rather than the rule. Foresters' management objectives are focused on management of forests for provision of forest goods and services for the nation, whereas villagers keep trees for social-cultural-spiritual-economic reasons, but rarely for firewood alone. Sometimes, what is important for villagers is seen as of 'minor importance' to foresters.

    Second, villagers traditionally, did not care about ownership of forests. However, ownership of valued-trees was well known. Notwithstanding such a situation, the government in Sudan intervened to manage the resource. Nonetheless, abolishment of the traditional Native Administrative system together with many other factors led to the situation where the state was unable to manage the resources on a sustainable basis. Hence, some of the tree/forest resources acquired the characteristics of the unowned, none-property resources.

    Third, most of the foresters see forest management mainly as consisting of a series of context-free technical activities, while villagers perform trees/forests management as part and parcel of their overall land use.

    Fourth, this study exposes social actors' appreciation concerning positive changes in each other's attitudes and behaviours and their willingness to manage forest resources jointly. Nevertheless, villagers and their leaders as well as officials have to be aware of and prepared for their new rights and responsibilities.

    Fifth, this study manifests that the formal forestry knowledge in Sudan is based on the assumption that wood is the main product. In most of their experiments forestry researchers look mainly into wood, and did not pay enough attention to non-timber- products. In addition, extension officers tend to disseminate unified, ready-made messages to various clients' segments. As well, in spite of the shown appreciation of local people's forestry knowledge, foresters rarely take villagers' observations and comments seriously.

    Sixth, women are becoming increasingly involved in forestry activities and the number of female foresters is increasing. Taking into consideration the fact that the rural Sudanese culture in many places does not allow easy interaction between male extension officers and village women, the need for female forestry extension officers seems to be well understood.

    Seventh, the following are among the learning points in relation to villagers' knowledge activities as depicted from this study:
    (1) For villagers researching and learning are inseparable. Deploying their surrounding environment in its totality, villagers carefully observe and learn experientially.
    (2) Local people's knowledge is embedded into different kinds of rituals and spiritual beliefs.
    (3) Villagers do not tend to reach to consensus and unified kind of knowledge and solutions.
    (4) Villagers normally exchange information among themselves during greetings; direct and indirect asking; certain occasions and locations such as funerals, market places and days, and religious/cultural feasts.

    Eighth, the findings of this study reveal that none of social actors alone has the technical/managerial capacity pertinent to sustainable management of forest resources. The necessary knowledge base is rather fragmented and unevenly scattered among different actors. Hence, we argued that in the absence of a suitable knowledge and information system, appropriate management of forest resources will be difficult. Forestry education has a role to play in facilitation of such knowledge and information system. Nonetheless, many economic, didactical and organizational problems remain as constraints for present institutions to perform better roles.

    Ninth, the results of this study came to support the idea that education is but one element which influences foresters' attitudes and behaviour. In reality, foresters' performance is determined by a composite of inter-related factors such as the work environment. Under the prevailing situation, learners and educators have neither enough time nor good motivation for creation of favourable learning environments.

    The main recommendations of this study are:
    (1) Foresters should take other social actors' perceptions, knowledge and management objectives into consideration when deciding about official management objectives and strategies.
    (2) Forestry educational institutions will and should have a role to play in facilitating various forest resources managers getting around a platform and discuss, learn and coordinate their resources to manage the resources on a sustainable basis. However, before being able to play such a role, they should start to see their roles as "experts' bureaux", but instead try to develop networking institutions.
    (3) Moreover, in an era of fast change, forest managers should learn more about learning. Nevertheless, to facilitate such kinds of learning, forestry educational institutions need to restructure their curricula involving other social actors and create channels for ongoing monitoring.
    (4) However, all the above mentioned requirements will be of limited effect in the absence of an overall conducive environment. Again, educators should not wait for these improvements to come, instead they should work very hard for the creation of such a conducive educational and learning environment.

    As a contribution towards development of such educational and learning environment, a model for forestry curriculum development has been proposed.

    NOPEX/Forest-Dynamo. Ground data collection and data analysis report : : fieldcampaigns in 1994 - 1995
    Oevelen, P.J. van; Woodhouse, I.H. - \ 1996
    Wageningen : Landbouwuniversiteit Wageningen (Rapport / Landbouwuniversiteit, Vakgroep Waterhuishouding 70) - 74
    remote sensing - toepassingen - bosbouw - houtteelt - bosbouwkundige handelingen - groei - milieufactoren - luchtkarteringen - zweden - remote sensing - applications - forestry - silviculture - forestry practices - growth - environmental factors - aerial surveys - sweden
    Groei en ontwikkeling van de menging Douglas-beuk; meer dan de som der delen?
    Bartelink, H.H. ; Tünnissen, A.T.F.M. - \ 1996
    Nederlands Bosbouwtijdschrift 68 (1996)1. - ISSN 0028-2057 - p. 2 - 6.
    bosbouw - houtteelt - bosbouwkundige handelingen - groei - milieufactoren - gemengde bossen - bomen - fagus sylvatica - pseudotsuga menziesii - gemengde opstanden - forestry - silviculture - forestry practices - growth - environmental factors - mixed forests - trees - fagus sylvatica - pseudotsuga menziesii - mixed stands
    Het nedersaksische groeiplaatsclassificatiesysteem en zijn toepasbaarheid in Nederland.
    Fanta, J. ; Kuiper, B. ; Bianchi, F.J.J.A. ; Rattink, M. - \ 1996
    Nederlands Bosbouwtijdschrift 68 (1996). - ISSN 0028-2057 - p. 168 - 170.
    bosbouw - houtteelt - bosbouwkundige handelingen - groei - milieufactoren - vegetatietypen - bossen - classificatie - duitsland - forestry - silviculture - forestry practices - growth - environmental factors - vegetation types - forests - classification - germany
    Phenology and growth of European trees in relation to climate change
    Kramer, K. - \ 1996
    Agricultural University. Promotor(en): J. Goudriaan; G.M.J. Mohren. - S.l. : Kramer - ISBN 9789054854647 - 210
    bosbouw - fenologie - houtteelt - bosbouwkundige handelingen - groei - milieufactoren - klimaatverandering - paleoklimatologie - Europa - forestry - phenology - silviculture - forestry practices - growth - environmental factors - climatic change - palaeoclimatology - Europe
    Research topics

    The relationships between climate and both phenology and growth of some important European tree species were studied to evaluate the potential impacts of climate change on trees and forests in Europe. In order to make such assessments, insight is required on the mechanisms how climatic variables interact with plant processes. The topics addressed in this study were: (1) the modelling of phenology, (2) the consequences of climate change on spring frost damage, (3) the importance of phenotypic plasticity, (4) the importance of phenology on the effects of climate change on growth of monospecies deciduous forests, and (5) the importance of phenology on the effects of climate change on growth of mixed-species deciduous forests.

    Modelling phenology

    To evaluate the impacts of climate change on growth of temperate deciduous tree species, the onset and cessation of the growth must be accurately described. A review is presented on eight models predicting the date of leaf unfolding depending on temperature. These models were fitted using 57 years of observations on the date of leaf unfolding of Fagus sylvatica in The Netherlands, and used to predict 40 years of similar observations collected in Germany. As conflicting experimental evidence exist on the role of photoperiod on leaf unfolding of Fagus sylvatica, photoperiod was incorporated into each of these models.

    The timing of leaf unfolding could best be described by a model in which the effects of chilling temperatures (-5 to +10°C) and forcing temperatures (>0°C) operate sequentially in time, according to a triangular and logistic function, respectively. Including photoperiod reduced the predicting power of this model.

    Spring frost damage

    Two studies presented in literature evaluate the effect of increasing winter temperature on the probability of spring frost damage to trees. However, one study predicted an increase, while the other predicted a decrease in the probability of spring frost damage. It is unclear whether the disparity is because: (1) different models were used, (2) different climatic warming scenarios used, or (3) the tree species at the different locations respond differently to warmer winters. To evaluate the effects of climatic warming to Larix decidua, Betula pubescens, Tilia platyphylla, Fagus sylvatica, Tilia cordata, Quercus rubra, Quercus robur, Fraxinus excelcior, Quercus petraea, Picea abies and Pinussylvestris in The Netherlands and in Germany, both models were fitted to long series of observations on the date of leaf unfolding of these tree species. The impact of the two scenarios (uniformly and non-uniformly changing winter temperature) on the date of leaf unfolding and on the probability of freezing temperature around that date was evaluated. To test the importance of adaptation to local climate, hypothetical provenance transfers were analysed.

    For tree species in The Netherlands and Germany the probability of spring frost damage will decrease, provided the variability in temperature does not change. The contradictory results found in literature could be ascribed to differences among provenances adapted to their local climate, rather than to differences between either the models or the climatic warming scenarios used in these studies.

    Plasticity

    To evaluate the potential response of individual trees to climatic warming, phenological observations of clones of Larix decidua, Betula pubescens, Tilia cordata, Populus canescens, Quercus robur, Fagus sylvatica, and Picea abies transferred over a large latitudinal range in Europe were analysed. The magnitude of the clone's response was compared to that of genetically different trees of the same species along a part of the latitudinal range, which were assumed to have adapted to their local climate.

    The responses of the date of leaf unfolding and leaf fall of the clones to temperature are similar in magnitude to those of the genetically different trees. This demonstrates that trees possess a considerable plasticity and are able to respond phenotypically to a major change in their local climate. For the clones of Larix decidua and Quercus robur the growing season may shorten with increasing temperature, because leaf fall is advanced more than leaf unfolding. In Betula pubescens and Populus canescens, leaf unfolding and leaf fall are advanced equally, whereas in Tilia cordata and Fagus sylvatica the date of leaf fall seems to be unaltered but leaf unfolding advances with increasing temperature. These differences in the duration of the growing season in response to increasing temperature may alter the competitive balance between the species in mixed stands.

    Descriptive dynamic models showed that most of the variance of the date of leaf unfolding can be accounted for by temperature. However, a generally applicable model of leaf fall based on temperature and/or photoperiod could not improve the null model, i.e. the mean date of leaf fall, because of variability in other environmental factors.

    The lowest temperature around the date of leaf unfolding and leaf fall differed among the clones. The hypothesis that the survival of the clones is curtailed by spring frosts was supported. Thus, these lowest temperatures around leaf unfolding may represent thresholds below which the species cannot survive.

    It is argued that these thresholds may be a particularly sensitive means to evaluate the impacts of climatic warming on the geographical distribution of tree species.

    Growth of monospecies forests

    The importance of three phenological types of deciduous tree for the effects of climate change on growth of monospecies forests was evaluated using the model FORGRO. The climate change scenarios used were a doubling of the C02 concentration (700 μmol mol -1) and an increase in temperature ranging from 0 to 7°C. To elucidate the relative importance of photosynthesis and allocation for this evaluation, models with different levels of mechanistic detail of photosynthesis and allocation were used. The photosynthesis approach of FORGRO was compared to the Farquhar and Von Caernmerer approach as formulated in PGEN (FORGRO-PGEN). Similarly, the allocation approach of FORGRO was compared to the transport-resistance approach, as formulated in the ITE-Edinburgh model (ITE-FORGRO). A sensitivity analysis was performed to ascertain whether the response of gross photosynthesis to a climate change scenario depends on the value assigned to parameters in these models, and to compare this sensitivity with the differences found between the phenological types. The differences in the response of annual gross photosynthesis ( Pg,a ) to the climate change scenarios between the phenological types were smaller according to ITE- FORGRO as compared to FORGRO. These differences are of a similar magnitude when comparing the two photosynthesis models. Furthermore, FORGRO-PGEN showed that the response of Pg,a to a 2 x [ 2 CO ] increases with rising temperature, thus compensating for the increase in respiration. For both FORGRO and ITEFORGRO, this C0 2 and temperature interaction was not found. Consequently, in these models the increase in respiration exceeded the increase in gross photosynthesis at the higher range of temperature rise. The sensitivity analysis showed that the models differ in the sensitivity of the response of Pg,a to a 2 x [C 2 O ] scenario combined with a temperature rise of 2°C ( C700 / T2 ), when parameter values change by ±25%. In FORGRO-PGEN, the magnitude of the response of Pg,a depended on the values of some of its parameters, especially those determining the Michaelis-Menten kinetics of Rubisco, which for these parameters exceeded the differences between the phenological types in this scenario. In both FORGRO and ITE-FORGRO, this sensitivity is similar to or less than the difference between the phenological types in the C700 / T2 scenario.

    Growth of mixed-species forests

    Using the same three phenological types and climate change scenarios, the effects of differences in phenology and spring frost damage on growth in mixed-species stands were evaluated using the models FORGRO and HYBRID. FORGRO highlights potential growth in managed forests, whereas HYBRID highlights feedbacks of carbon, water and nitrogen cycles in General Vegetation Types, based on gap model theory. Furthermore, the importance of inaccuracy of the phenological model for growth in mixed-species stands was evaluated by comparing the modelling approach with a regression approach.

    The results of the climate change scenarios indicate for both FORGRO and HYBRID that: (1) the differences in NPP of the three phenological types considered are enhanced when grown in a mixed-species stand compared to a monospecies stand; and (2) the consequences of frost damage on growth is more prominent in mixed-species stands than in monospecies stands.

    Considering the accuracy of the modelling approach compared to the regression approach for the timing of leaf unfolding and spring frost damage, the sequential model of leaf unfolding shows a similar response of the NPP as the regression approach, both for the monospecies and the mixed-species situation. The modelling approach yields, however, larger differences in the NPP between the phenological types because the model predicts a greater advancement of leaf unfolding than the regression model. Comparing the regression approach to the modelling approach for frost hardiness, the regression approach shows a greater frequency of frost damage, because according to the model, the minimum level of frost hardiness is attained after the date of leaf unfolding, thus reducing this frequency.

    The differences in phenological response to temperature can be used to evaluate the consequences of climate change on the geographical distributions of species.

    Oogsttechniek heeft grote invloed op bewaring hout voor energiedoeleinden
    Gigler, J.K. ; Bosma, A.H. - \ 1995
    Landbouwmechanisatie 46 (1995)8. - ISSN 0023-7795 - p. 16 - 17.
    energie - energiegebruik - energiebronnen - bosbouw - bosbouwtechniek - bosbouwkundige handelingen - brandhout - stapelplaats - houtkap - stamhout - natuurlijke hulpbronnen - salicaceae - opslag - bomen - nuttig gebruik - hout - arbeidskunde - energy - energy consumption - energy sources - forestry - forestry engineering - forestry practices - fuelwood - landings - logging - logs - natural resources - salicaceae - storage - trees - utilization - wood - work study
    Elektriciteit uit energiegewassen als wilg kan in de toekomst realiteit worden. Het IMAG-DLO onderzoekt of de Zweedse kennis van en ervaring met de wilgenteelt ook in Nederland past
    Ruim twintig jaar beplantingsproef Broekpolder : proefveldresultaten over de periode 1970 - 1991
    Peeters, J.P. - \ 1994
    Wageningen : IBN-DLO (IBN - rapport 107) - 155
    bosbouw - bebossing - baggerspeciedepots - industrieterreinen - mijnstort - bodemvruchtbaarheid - houtteelt - bosbouwkundige handelingen - groei - milieufactoren - havens - bagger - stort - sediment - modder - Nederland - zuid-holland - westland - forestry - afforestation - spoil banks - industrial sites - mine spoil - soil fertility - silviculture - forestry practices - growth - environmental factors - harbours - dredgings - spoil - sediment - mud - Netherlands - zuid-holland - westland
    Growth and nutrition of Douglas fir, Scots pine and pedunculate oak in relation to soil acidification
    Visser, P.H.B. de - \ 1994
    Agricultural University. Promotor(en): N. van Breemen; G.R. Findenegg; W.G. Keltjens. - S.l. : De Visser - ISBN 9789054852902 - 185
    bosbouw - houtteelt - bosbouwkundige handelingen - groei - milieufactoren - bomen - bodemchemie - bodemaciditeit - verzuring - beluchting - voedingsstoffenopname (planten) - bodem ph - plantenfysiologie - neerslag - chemische eigenschappen - zuurgraad - zure regen - forestry - silviculture - forestry practices - growth - environmental factors - trees - soil chemistry - soil acidity - acidification - aeration - nutrient uptake - soil ph - plant physiology - precipitation - chemical properties - acidity - acid rain

    In a Douglas fir ( Pseudotsuga menziesii (Mirb.) Franco) and in a Scots pine ( Pinus sylvestris L.) stand on sandy soil in the Netherlands, inputs of water, nutrients and acid loads were changed for four years. Effects of soil changes on growth and nutrition were compared with similar foreign experiments, and with some soil-tree relationships in an oak ( Quercus robur L.) stand, which had different soil types within the site. Water limitations in the stands were demonstrated by a 40% to 50% increase in tree basal area growth from water additions of 3 mm d -1or more. Needle N and K contents were depressed and needle shedding was retarded in autumn by irrigation in the Douglas fir stand. In both coniferous stands mineralization and nitrate leaching were enhanced by the moister soil conditions. The modest growth response to nutrient applications in addition to irrigation, proved that no nutrient deficiencies were present at the sites, although foliar P and K increased instantly. The application of dissolved K, Mg and Ca to both acid forest soils increased Al dissolution and decreased Ca/Al ratios in soil solution. This soil reaction was even stronger when applying dissolved (NH 4 ) 2 SO 4 and was explained by the combined effect of soil exchange processes and root uptake of the applied cations, both increasing soil acidification. The applied (NH 4 ) 2 SO 4 initially enhanced tree growth, later followed by growth reduction in the forest stand and tree death in a pot trial at similar NH 4 supply rates.

    Douglas fir growth was higher at optimal water and nutrient applications when atmospheric loads were excluded. The reduced NH 4 inputs resulted in a decrease of NO 3 leaching, in a lower needle N concentration and tended to decrease Al concentrations and Al/Ca ratios in soil solution relative to the treatment with atmospheric loads.

    Transpiration of Douglas fir, as measured from sapflow, was drastically reduced during summer drought. Irrigated trees showed optimal transpiration rates and were found to absorb water more readily after rain events relative to previously water-stressed trees. NH 4 applications in a pot trial initially increased shoot growth and transpiration of juvenile Douglas fir, but strong soil acidification later impaired root functioning and water uptake.

    De bosbouw vergt een holistische benadering.
    Oldeman, R.A.A. - \ 1994
    Nederlands Bosbouwtijdschrift 66 (1994)1. - ISSN 0028-2057 - p. 13 - 19.
    conservering - bosbedrijfsvoering - bosbouw - bosbouwkundige handelingen - nederland - sociale economie - conservation - forest management - forestry - forestry practices - netherlands - socioeconomics
    Verloofing: misbruik van bossen of acceptabele bosbeheersmaatregel?
    Filius, A.M. - \ 1994
    Nederlands Bosbouwtijdschrift 66 (1994)6. - ISSN 0028-2057 - p. 226 - 234.
    bosbouw - gemengde bossen - bosbouwkundige handelingen - kosten - rentabiliteit - bosbouweconomie - bossen - bosbedrijfsvoering - nederland - gemengde opstanden - veluwe - gelderland - forestry - mixed forests - forestry practices - costs - profitability - forest economics - forests - forest management - netherlands - mixed stands - veluwe - gelderland
    Kosten per ha van omvorming van douglas naar eik/groveden en eik/groveden/Japanse lariks voor de Veluwe en kantekeningen bij het bosbeheerbeleid ten aanzien van verloofing
    Bosbeleidskunde in ontwikkeling; een systematische benadering.
    Vliet, C.J.M. van - \ 1993
    Nederlands Bosbouwtijdschrift 65 (1993)3. - ISSN 0028-2057 - p. 136 - 146.
    bosbouw - bosbouwkundige handelingen - sociale economie - regering - overheidsbeleid - bedrijfsvoering - forestry - forestry practices - socioeconomics - government - government policy - management
    Bomen over bossen en mensen in 't verschiet
    Maaren, A. van - \ 1993
    Wageningen : LU - 33
    bosbouw - bosbouwkundige handelingen - sociale economie - hoger onderwijs - sociaal milieu - colleges (hoorcolleges) - bosbouweconomie - bossen - bosbedrijfsvoering - economisch beleid - nederland - sociografie - sociale situatie - veluwe - gelderland - openbare redes - forestry - forestry practices - socioeconomics - higher education - social environment - lectures - forest economics - forests - forest management - economic policy - netherlands - sociography - social situation - veluwe - gelderland - public speeches
    Rede Landbouwuniversiteit Wageningen, 24 juni 1993
    Taaktijden voor de boomkwekerij
    Lookeren Campagne, P. van - \ 1992
    Wageningen : IMAG-DLO (Nota / Instituut voor Mechanisatie, Arbeid en Gebouwen 203)
    boomkwekerijen - bosbouw - bosbouwkundige handelingen - functieuitoefening - arbeid (werk) - plantenkwekerijen - tijd - werkplanning - arbeidskunde - bos- en haagplantsoen - forest nurseries - forestry - forestry practices - job performance - labour - nurseries - time - work planning - work study - woody nursery stock
    Specialisatie in de boomkwekerij
    Spenkelink, H. - \ 1992
    Boskoop : Proefstation voor de Boomkwekerij (Rapport / Boomteeltpraktijkonderzoek nr. 18) - 46
    arbeidsverdeling - boomkwekerijen - bosbouw - bosbouwkundige handelingen - Nederland - houtachtige planten als sierplanten - specialisatie - gespecialiseerde landbouw - division of labour - forest nurseries - forestry - forestry practices - Netherlands - ornamental woody plants - specialization - specialized farming
    Bedrijfseconomische analyse van de teelt van naaldhoutbosplantsoen : vollegrondsteelt vergeleken met plug- en containerteelt (project 3300; activiteit 03)
    Spenkelink, H. - \ 1992
    Boskoop : Proefstation voor de Boomkwekerij (Rapport / Boomteeltpraktijkonderzoek nr. 19) - 32
    containers - financiën - bosbouweconomie - bosbedrijfsvoering - boomkwekerijen - bosbomen - bosbouw - bosbouwkundige handelingen - nederland - houtachtige planten als sierplanten - potcultuur - bomen - slangen (buizen) - pinus sylvestris - pseudotsuga menziesii - pinopsida - containers - finance - forest economics - forest management - forest nurseries - forest trees - forestry - forestry practices - netherlands - ornamental woody plants - pot culture - trees - tubes - pinus sylvestris - pseudotsuga menziesii - pinopsida
    Resultaten van een dunningsproef met toekomstbomen in es
    Oosterbaan, A. ; Dik, E.J. - \ 1991
    Wageningen : De Dorschkamp (Rapport / De Dorschkamp Instituut voor Bosbouw en Groenbeheer nr. 630) - 34
    bosbouw - bomen - dunnen - habitus - levensvorm - plantenontwikkeling - nederland - onderzoek - houtteelt - bosbouwkundige handelingen - groei - milieufactoren - fraxinus excelsior - bosopstanden - forestry - trees - thinning - habit - life form - plant development - netherlands - research - silviculture - forestry practices - growth - environmental factors - fraxinus excelsior - forest stands
    Aanleg en beheer van bos en beplantingen
    Schuetz, P.R. ; Tol, G. van - \ 1990
    Wageningen : Pudoc - 504
    bosbouw - klimaat - houtteelt - houtkap - bosbouwtechniek - arbeidskunde - bosbouwkundige handelingen - bosschade - bosplagen - achteruitgang, bossen - afsterving - houtmeetkunde - bosbedrijfsvoering - bosbouweconomie - bosproducten - bos- en houtproductenindustrieën - handel - marketing - economie - bossen - bosbescherming - bospathologie - forestry - climate - silviculture - logging - forestry engineering - work study - forestry practices - forest damage - forest pests - forest decline - dieback - mensuration - forest management - forest economics - forest products - forest products industries - trade - marketing - economics - forests - protection of forests - forest pathology
    De betekenis van de watervoorziening voor de boomgroei in Nederland : voorgeschiedenis, onderzoek en resultaten
    Burg, J. van den - \ 1990
    Wageningen : De Dorschkamp (Rapport / De Dorschkamp Instituut voor Bosbouw en Groenbeheer nr. 599) - 98
    bosbouw - bodemwater - permeabiliteit - absorptie - hygroscopiciteit - bodembescherming - waterbescherming - erosie - hydrologie - beheer van waterbekkens - wortels - plantenontwikkeling - bosschade - beschadigingen door droogte - beschadiging door hitte - schade - vergoeding - nederland - houtteelt - bosbouwkundige handelingen - groei - milieufactoren - boswaardebepaling - forestry - soil water - permeability - absorption - hygroscopicity - soil conservation - water conservation - erosion - hydrology - watershed management - roots - plant development - forest damage - drought injury - heat injury - damage - compensation - netherlands - silviculture - forestry practices - growth - environmental factors - forest valuation
    De jeugdgroei van enkele inheemse loofboomsoorten in relatie tot de groeiplaats
    Jager, K. - \ 1990
    Wageningen : De Dorschkamp (Rapport / "De Dorschkamp" Instituut voor Bosbouw en Groenbeheer nr. 596) - 56
    bosbouw - bomen - houtteelt - bosbouwkundige handelingen - groei - milieufactoren - waterrelaties - voedingsstoffen - wortels - bodemchemie - bodemeigenschappen - hoogte - diameter - volume - bepaling van groeiplaatshoedanigheden - bebossing - groene zones - heggen - nederland - forestry - trees - silviculture - forestry practices - growth - environmental factors - water relations - nutrients - roots - soil chemistry - soil properties - height - diameter - volume - site class assessment - afforestation - green belts - hedges - netherlands
    Resultaten van praktijkbekalkingen in eerste- en tweede- generatie - heidebebossingen in de boswachterij Ruinen
    Burg, J. van den - \ 1990
    Wageningen : De Dorschkamp (Rapport / "De Dorschkamp" Instituut voor Bosbouw en Groenbeheer nr. 577) - 73
    bosbouw - bomen - voedingsstoffenbehoeften - bossen - bodemvruchtbaarheid - vegetatietypen - bodemchemie - bodemaciditeit - verzuring - beluchting - voedingsstoffenopname (planten) - bodem ph - planteffecten - bodem - humus - bodemprofielen - minerale gronden - horizonten - mineralen - as - planten - mineraalgehalte - houtteelt - bosbouwkundige handelingen - groei - milieufactoren - nederland - bosopstanden - bemesting - drenthe - forestry - trees - nutrient requirements - forests - soil fertility - vegetation types - soil chemistry - soil acidity - acidification - aeration - nutrient uptake - soil ph - plant effects - soil - humus - soil profiles - mineral soils - horizons - minerals - ash - plants - mineral content - silviculture - forestry practices - growth - environmental factors - netherlands - forest stands - fertilizer application - drenthe
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