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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    Opstanden voor zaadoogst van de inheemse fladderiep uitgebreid
    Vries, S.M.G. de; Kopinga, J. - \ 2016
    Vakblad Natuur Bos Landschap 13 (2016)121. - ISSN 1572-7610 - p. 18 - 19.
    fladderiep - bosbestanden - ulmus - opstandsontwikkeling - natuurlijke opstanden - zaailingen - bosbeheer - forest resources - ulmus - stand development - natural stands - seedlings - forest administration
    Voor de bosbouwers die wat willen gaan doen met inheemse iepenhout, is het assortiment met autochtone herkomst toegenomen. Van de fladderiep stond in de 7e Rassenlijst (2002) tot voor kort slechts één opstand vermeld, maar daar is nu een opstand in Twente bijgekomen: Denekamp-01, NL.SI.1.3.09.01. De opstand laat zien dat in Nederland niet alleen klonaal vermeerderde selecties, maar ook zaailingpopulaties van deze iep zich kunnen ontwikkelen tot redelijk recht groeiende bomen van imponerende afmeting. Zowel solitair als in bosverband. En bestand tegen iepziekte!
    DNA-onderzoek bewijst oorsprong van eiken
    Buiteveld, J. ; Vries, S.M.G. de - \ 2005
    De Boomkwekerij 18 (2005)35. - ISSN 0923-2443 - p. 16 - 17.
    quercus - centra van herkomst - bronnen - genetische bronnen - migratie - verspreiding - ecologie - dna - chloroplast dna - cytoplasmatische overerving - natuurlijke opstanden - rassenlijsten - quercus - centres of origin - sources - genetic resources - migration - dispersal - ecology - dna - chloroplast dna - cytoplasmic inheritance - natural stands - descriptive list of varieties
    Historische en uiterlijke gegevens zeggen heel veel over het autochtone karakter van een populatie, maar met DNA-gegevens ben je pas écht zeker. Autochtone opstanden kunnen onder de categorie 'van bekende oorsprong' op de Rassenlijst geplaatst worden. Hiermee hebben ze een officiële status, waarmee het materiaal eruit verhandeld kan worden
    Natuurlijke bosverjonging komt niet zomaar van de grond
    Grimberg, G.T.M. ; Oosterbaan, A. - \ 2003
    Vakblad Natuurbeheer 42 (2003)1. - ISSN 1388-4875 - p. 6 - 9.
    verjonging - natuurlijke verjonging - bossen - bosbeheer - bosbedrijfsvoering - bosbouw - houtteeltkundige systemen - lichten van opstanden - pleksgewijze kap - grondvoorbereiding - grondbewerking - verzorgen van jonge opstanden - bosschade - beweidingsschade - schadepreventie - botanische samenstelling - natuurlijke opstanden - regeneration - natural regeneration - forests - forest administration - forest management - forestry - silvicultural systems - improvement fellings - patch cutting - site preparation - tillage - tending - forest damage - browsing damage - loss prevention - botanical composition - natural stands
    Aan de hand van resultaten van onderzoek en ervaringen van beheerders heeft de contactgroep 'Natuurlijke bosverjonging' maatregelen voor het sturen van de natuurlijke bosverjonging tegen het licht gehouden. Om de verjonging een kans te geven en een goede soortensamenstelling te krijgen kan gedacht worden aan lichting (grootte van het verjongingsgat), bodemvoorbereiding door oppervlakkige grondbewerking (schijveneg), bescherming tegen wildschade (door afrasteringen of het maken van grote verjongingsvlakten), en niet te vroeg ingrijpen in een jong stadium
    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
    Bosreservaten: waarom?
    Broekmeyer, M.E.A. - \ 1999
    De Levende Natuur 100 (1999)5. - ISSN 0024-1520 - p. 150 - 153.
    bossen - bosbouw - beschermde bossen - natuurreservaten - bosecologie - natuurlijke verjonging - plantensuccessie - bosinventarisaties - verjongingsinventarisaties - monitoring - onderzoek - nederland - natuurlijke opstanden - forests - forestry - reserved forests - nature reserves - forest ecology - natural regeneration - plant succession - forest inventories - regeneration surveys - monitoring - research - netherlands - natural stands
    In Nederland zijn 60 bosreservaten aangewezen die representatief zijn voor natuurlijke bosgemeenschappen. In het kader van het Programma Bosreservaten wordt hier onderzoek verricht naar de spontane processen in niet beheerde bossen
    A-locatie bossen in Drenthe : kenschets, beoordeling en adviezen met betrekking tot behoud en ontwikkeling van relicten van inheemse bosgemeenschappen in de provincie Drenthe
    Ouden, J.B. den - \ 1998
    Wageningen : IBN-DLO (IBN - rapport 300) - 101
    bosbouw - bossen - geschiedenis - plantensuccessie - periodiciteit - vegetatie - analyse - ecologie - bosecologie - flora - bescherming - conservering - nederland - natuurlijke opstanden - drenthe - forestry - forests - history - plant succession - periodicity - vegetation - analysis - ecology - forest ecology - flora - protection - conservation - netherlands - natural stands - drenthe
    A-locatie bossen in Noord-Brabant : kenschets, beoordeling en adviezen met betrekking tot behoud en ontwikkeling van relicten van inheemse bosgemeenschappen in de provincie Noord-Brabant
    Ouden, J.B. den; Broekmeyer, M.E.A. - \ 1998
    Wageningen : IBN-DLO (IBN - rapport 387) - 114
    bosbouw - bossen - geschiedenis - plantensuccessie - periodiciteit - vegetatie - analyse - ecologie - bosecologie - flora - bescherming - conservering - nederland - natuurlijke opstanden - noord-brabant - forestry - forests - history - plant succession - periodicity - vegetation - analysis - ecology - forest ecology - flora - protection - conservation - netherlands - natural stands - noord-brabant
    A-locatiebossen in Zuid-Holland; kenschets, beoordeling en adviezen met betrekking tot behoud en ontwikkeling van relicten van inheemse bosgemeenschappen in de provincie Zuid-Holland.
    Ouden, J.B. den - \ 1998
    Wageningen : IBN-DLO (IBN-rapport 377) - 120
    bosbouw - bossen - geschiedenis - plantensuccessie - periodiciteit - vegetatie - analyse - ecologie - bosecologie - flora - bescherming - conservering - nederland - natuurlijke opstanden - zuid-holland - forestry - forests - history - plant succession - periodicity - vegetation - analysis - ecology - forest ecology - flora - protection - conservation - netherlands - natural stands - zuid-holland
    A-locatie bossen in Zeeland
    Dort, K.W. van; Ouden, J.B. den - \ 1998
    Wageningen : IBN-DLO (IBN-rapport 386) - 39
    bosbouw - bossen - geschiedenis - plantensuccessie - periodiciteit - vegetatie - analyse - ecologie - bosecologie - flora - bescherming - conservering - nederland - natuurlijke opstanden - zeeland - forestry - forests - history - plant succession - periodicity - vegetation - analysis - ecology - forest ecology - flora - protection - conservation - netherlands - natural stands - zeeland
    A-locatie bossen in Flevoland
    Dort, K.W. van; Ouden, J.B. den - \ 1998
    Wageningen : IBN-DLO (IBN-rapport 383) - 32
    bosbouw - bossen - geschiedenis - plantensuccessie - periodiciteit - vegetatie - analyse - ecologie - bosecologie - flora - bescherming - conservering - nederland - natuurlijke opstanden - flevoland - forestry - forests - history - plant succession - periodicity - vegetation - analysis - ecology - forest ecology - flora - protection - conservation - netherlands - natural stands - flevoland
    A-locatie bossen in Friesland
    Dort, K.W. van; Ouden, J.B. den - \ 1998
    Wageningen : IBN-DLO (IBN-rapport 382) - 66
    bosbouw - bosecologie - bossen - geschiedenis - analyse - ecologie - conservering - flora - vegetatie - plantensuccessie - periodiciteit - bescherming - nederland - natuurlijke opstanden - friesland - forestry - forest ecology - forests - history - analysis - ecology - conservation - flora - vegetation - plant succession - periodicity - protection - netherlands - natural stands - friesland
    A-locatie bossen in Utrecht : kenschets, beoordeling en adviezen met betrekking tot behoud en ontwikkeling van relicten van inheemse bosgemeenschappen in de provincie Utrecht
    Ouden, J.B. den; Broekmeyer, M.E.A. - \ 1997
    Wageningen : IBN-DLO (IBN - rapport 299) - 83
    bosbouw - standplaatsfactoren - bepaling van groeiplaatshoedanigheden - bossen - milieubescherming - conservering - flora - vegetatie - bescherming - nederland - natuurlijke opstanden - utrecht - forestry - site factors - site class assessment - forests - environmental protection - conservation - flora - vegetation - protection - netherlands - natural stands - utrecht
    A-locatie bossen in Noord-Holland : kenschets, beoordeling en adviezen met betrekking tot beho
    Broekmeyer, M.E.A. ; Ouden, J.B. den - \ 1997
    Wageningen : IBN-DLO (IBN - rapport 301) - 85
    bosbouw - standplaatsfactoren - bepaling van groeiplaatshoedanigheden - bossen - milieubescherming - conservering - flora - vegetatie - bescherming - nederland - natuurlijke opstanden - noord-holland - forestry - site factors - site class assessment - forests - environmental protection - conservation - flora - vegetation - protection - netherlands - natural stands - noord-holland
    Natuurboszones : een procedure voor aanwijzing
    Bijlsma, R.J. ; Kalkhoven, J.T.R. ; Koop, H.G.J.M. - \ 1997
    Wageningen : IBN-DLO (IBN - rapport 328) - 30
    bosbouw - bossen - natuurreservaten - natuurbescherming - locatiekeuze - selectie - nederland - natuurlijke opstanden - forestry - forests - nature reserves - nature conservation - site selection - selection - netherlands - natural stands
    A-locatie bossen in Overijssel: kenschets, beoordeling en adviezen met betrekking tot behoud en ontwikkeling van relicten van inheemse bosgemeenschappen in de provincie Overijssel
    Ouden, J.B. den; Broekmeyer, M.E.A. ; Koop, H.G.J.M. - \ 1997
    Wageningen : DLO-Instituut voor Bos- en Natuuronderzoek (IBN-rapport 272) - 177
    bosbouw - bossen - geschiedenis - plantensuccessie - periodiciteit - vegetatie - analyse - ecologie - bosecologie - flora - bescherming - conservering - nederland - natuurlijke opstanden - overijssel - forestry - forests - history - plant succession - periodicity - vegetation - analysis - ecology - forest ecology - flora - protection - conservation - netherlands - natural stands - overijssel
    Trees and light : tree development and morphology in relation to light availability in a tropical rain forest in French Guiana
    Sterck, F.J. - \ 1997
    Agricultural University. Promotor(en): H.H.T. Prins; F.J.J.M. Bongers. - S.l. : Sterck - ISBN 9789054856733 - 122
    bosbouw - habitus - levensvorm - plantenontwikkeling - plantenecologie - licht - plantenmorfologie - tropische regenbossen - vegetatie - tropen - frans-guyana - natuurlijke opstanden - forestry - habit - life form - plant development - plant ecology - light - plant morphology - tropical rain forests - vegetation - tropics - french guiana - natural stands

    Tropical rain forest trees spend their life in a heterogeneous light environment. During their life history, they may change their growth in relation to different levels of light availability. Some of their physiological processes (e.g. photosynthesis, carbon allocation, and meristern activity) change with light availability, and tune their development and morphology to the ambient light levels. The underlying physiological processes are not investigated in the present study. The focus is on the development and morphology of trees of canopy species in relation to the light availability in tropical rain forest. The possible consequences for survival, growth, and reproduction of trees are not assessed directly, but are discussed on a speculative basis.

    The relationships between the light environment, tree development, and morphology are investigated for trees of different size, ranging from small saplings to trees of adult stage. Trees of increasing size are compared in order to explore the changes in tree development and morphology, and their relation to the light environment, with ontogeny. Ontogeny is referred to as the overall growth and development pattern during tree life, both for individual trees and (in more general) for a given tree species.

    The field work for this thesis was carried out in French Guiana. This country in the north-east of South America has an area of 83.000 km 2and is covered by evergreen tropical rain forest. The field work was conducted at two biological stations. 'The Piste St. Elie' station is located 30 km from the coast, south of the town of Sinnamary, and the biological station 'Les Nouragues' is located 100 km from the coast, south of Cayenne. Two canopy tree species were selected for this study: Dicorynia guianensis Amshoff. (Caesalpiniaceae) and Vouacapoua americana Aubl. (Caesalpiniaceae). Both are common species in the forests of French Guiana, and are considered late successionals or shadetolerant species (Schulz 1960). In some chapters, these species are compared with an early successional (light demanding) species, Goupia glabra Aubl. (Celastraceae). Trees of these three species are harvested for their timber in French Guiana and its surrounding countries.

    The trees that were shorter than 20 rn had not yet reached the open upper canopy. These trees usually occur at relatively low light levels. Although these trees may differ in height (from 0 to 20 m), they usually show the same type of growth response to ambient light levels. They produced more growth units and more leaves at higher light availability. They thus increased their total leaf area and leaf area index (LAI, a measure for the number of leaf layers in the crown) as a response to higher light levels. Under persisting high light levels, the increase in total leaf area may enable these trees to fix more carbohydrates (i.e. carbon) for successful growth and survival in the future. Trees with a high LAI at higher light availability, in combination with more columnar shaped crowns, achieve net photosynthesis (more carbon intake than consumption by leaves) at the least possible cost for leaf area support. In contrast, trees with more planar crowns and lower LAI at lower light availability may avoid self-shading of leaves, but risk higher costs for leaf area support.

    Trees also produced shorter growth units at lower light availability, and thus spaced their leaves at shorter distances than trees at higher light availability. In more closely spaced leaves, the investments for the support of one leaf are lower. As leaf size did not change in relation to light availability, trees displayed their leaf area more economically (at lower carbon costs) at lower light availability. In this way, they increased light interception per unit of fixed carbon, and they may thus be better able to survive the shade.

    Dicorynia and Vouacapoua trees also grew faster in height with increasing light availability. In general, trees may reduce their height growth because low light levels simply limit growth. At low light levels, trees are shaded by taller neighbouring trees which intercept the majority of light above them, but they may survive for some time by producing their leaf area slowly and efficiently. When light levels increase because one (or more) of the taller neighbours falls down, trees start to increase their height growth, and may compete with their neighbours for newly available light and space. For both species studied, it was shown that height growth further increased at very high light levels in large gaps through preferential growth of the leader (axis which supports the uppermost apical meristern of the crown) over the other axes in the crown. At lower light levels, individuals did not show preferential growth of the leader. Thus, height growth increased not only because the higher light levels are less growth limiting, but also because of preferential growth of the leader.

    These growth responses to light refer to trees (up to 20 m tall) that were still heading for the canopy. The taller trees (heights of sampled trees range between 26 and 37 m) at higher light availability in the upper canopy had a larger total leaf area and total branch length than the trees shorter than 20 m. These taller trees also produced larger and more planar shaped crowns, did not further increase their LAI, and decreased their leader growth and the space between leaves, as compared with the smaller individuals. The shift to a wider crown is probably caused by increasing light (and space) availability, and may constrain a further increase in the LAI (the leaves occurred over a much larger horizontal area). The lower leader growth and the production of leaves at shorter distances indicate that these taller trees changed from investments in vertical expansion to investments in the replacement of leaves (and flowers).

    The increasing stature with ontogeny has to be balanced by mechanical strength (thickness). This strength is needed to carry the increasing tree weight and to resist wind stress. The mechanical design expresses the balance between overall tree stature (in terms of weight or wind force experienced by the tree) and tree (mechanical) strength. The changes in mechanical design with ontogeny were investigated for Goupia, Dicorynia, and Vouacapoua using two models. (1) The elastic-stability model emphasises the mechanical strength against its own weight. Using this model, it was shown that trees of the study species decreased their 'safety margins' (strength) early in ontogeny, but increased their margins of safety later. Trees had their lowest margins at a stem diameter of 15 to 25 em. These margins were close to the theoretical minimum, i.e. trees would buckle under their own weight if they were slightly more slenderly built (taller at a given diameter). In comparison with some temperate tree species, the trees of the present study appeared to have lower safety margins because they were more slender. Slenderness (height/diameter ratio), however, is only one of the factors determining the strength of a tree. The denser and stiffer wood of tropical trees may increase the mechanical strength of tropical trees in comparison with temperate trees. Another explanation for the lower safety margins of tropical trees is that they are exposed to lower external stress forms than temperate trees. Temperate trees experience heavy storms and snow loads during their life, whereas the trees of the present study do not experience such forms of stress. (2) The constant-stress model emphasises the mechanical strength over wind stress on the tree. For the species of study, it was shown that the safety margins against wind stress increased with ontogeny. This was in line with the expectations, because wind stress is likely to increase with increasing tree stature. Finally, the influence of light availability on mechanical tree design could not be investigated. The trees studied had long life-histories under unknown light conditions, and therefore did not show a significant response within the 2-3 years of investigation.

    The ecological knowledge on commercial tree species presented in this work is thought to be useful for the fine tuning and improvement of forest management systems. In these systems, canopy gaps of different size are created, and they may affect the growth of trees. The results of this thesis indicate that manipulations of light availability (either by killing dominant trees thus inducing light level increase, or by shading) in forests may increase the timber production in trees. Besides this, the follow-up to this study may provi de morphological traits that can be used to indicate the growth potential of trees in relation to the light environment. It is suggested that there is a need for knowledge on the growth response of trees (both in terms of timber production, morphology and development) to the whole range of light availability. Manipulations of the light environment may then be tuned to individual trees of commercial species in order to approach the light conditions that provoke the desired growth response. In general, fundamental research on tree growth in a natural habitat, extended by research on tree growth at higher light levels outside the natural habitat, may provide valuable insights for the improvement of forest management systems.

    A-locatie bossen in Limburg; kenschets, beoordeling en adviezen met betrekking tot behoud en ontwikkeling van bosrelicten in de provincie Limburg
    Ouden, J.B. den - \ 1995
    Unknown Publisher (IBN-rapport 136) - 181
    analyse - conservering - ecologie - flora - bosecologie - bosbouw - bossen - geschiedenis - periodiciteit - plantensuccessie - bescherming - vegetatie - nederland - natuurlijke opstanden - limburg - analysis - conservation - ecology - flora - forest ecology - forestry - forests - history - periodicity - plant succession - protection - vegetation - netherlands - natural stands - limburg
    Bosdynamiek in de Otterskooi
    Clerkx, A.P.P.M. ; Broekmeyer, M.E.A. ; Koop, H. - \ 1995
    Nederlands Bosbouwtijdschrift 67 (1995)5. - ISSN 0028-2057 - p. 178 - 184.
    bosbouw - natuurlijke opstanden - overijssel - forestry - natural stands - overijssel
    Genetische kwaliteit inheemse bomen en struiken: Deelproject: Inheems genenmateriaal in de Achterhoek rond Winterswijk
    Maes, N.C.M. - \ 1994
    Wageningen : DLO-Instituut voor Bos- en Natuuronderzoek (IBN-rapport 076) - 75
    bomen - struiken - genetica - ecotonen - natuurlijke opstanden - gelderland - achterhoek - trees - shrubs - genetics - ecotones - natural stands - gelderland - achterhoek
    Miombo trees and mycorrhizae : ecological strategies, a basis for afforestation
    Munyanziza, E. - \ 1994
    Agricultural University. Promotor(en): R.A.A. Oldeman; T.W. Kuyper. - S.l. : Munyanziza - ISBN 9789054852681 - 193
    bosbouw - mycorrhizae - boomkwekerijen - bodeminoculatie - beplanten - aanslaan van het gewasbestand - tanzania - bebossing - natuurlijke opstanden - forestry - mycorrhizas - forest nurseries - soil inoculation - planting - stand establishment - tanzania - afforestation - natural stands

    This project has covered one or several aspects of the life cycle of the main miombo tree species, namely Afzelia quanzensis ,Brachystegia microphylla, Brachystegia spiciformis ,Julbernardia globifloraand Pterocarpus angolensis . These aspects included natural and artificial regeneration, fertilization, artificial inoculation of seedlings and natural occurrence of mycorrhizae on field-grown seedlings. Mycorrhizal survey of pine seedlings in various nurseries and inoculation trials on pines with exotic and indigenous fungi had also been conducted. The ultimate goal was to contribute to the development of techniques needed for the silviculture of miombo tree species.

    Seeds of B. speciformis , J. globiflora and A. quanzensis germinated within 3 weeks in nature provided there was regular rain. Seeds of P. angolensis possessed dormancy. Providing water was not enough to induce germination. In the greenhouse a hot wire scarifier boosted their germination to more than 90% within less than two weeks. Outside rain had a clear positive influence on the germination of scarified surfacesown seeds in the greenhouse. Germination was always initiated by outside rain. All species tested were sensitive to fires. For A. quanzensis germination tests were carried out at 10, 15 and 25°C. Seedlings germinated only at 25°C. Germination failures were also encountered in the field in the cool highlands of Tanzania.

    Seedlings of the above named indigenous species were raised in the nursery or observed in the miombo woodlands. A number of facts emerged.
    A big share of carbon is allocated to the development of the taproot. In the nursery, pruning the taproot interfered with the natural survival strategy of seedlings and caused a sharp depression in seedling growth. This was observed on J. globiflora and P. angolensis . The initial growth rate of the miombo tree seedlings covered here is far higher than that achieved by pines. As observed in Morogoro on seedlings of A. quanzensis , more than 70 percent of the height achieved in one year is attained in the first 2 months. Miombo species with big seeds such as A. quanzensis , had an initial higher growth rate than small-seeded species.

    The effect of drought on A. quanzensis seedling growth and survival during early stage of growth was studied. Inoculated or non- inoculated potted nursery seedlings were irrigated once a day, once every three days or once every four days. Induced drought had a negative effect on biomass accumulation. Non-drought treated seedlings were more than 4 times as heavy than treated ones. Inoculation did not counteract the effect of drought. Inoculated, drought-treated seedlings developed only one mycorrhizal type. The mycorrhizae in this treatment were shrunk and had a very thin sheath. Infection percentage was lower than 10%. Non-drought treated inoculated seedlings developed more than one type including that in treated seedlings. Infection rate was above 50%.

    A. quanzensis seedlings were observed under natural dry circumstances in the miombo woodlands for survival and mycorrhizal development. All seedlings survived and all formed one single mycorrhizal type similar to that in seedlings watered once every 4 days. All feeder roots were infected. Survival was 100%.
    Seedlings in the miombo woodlands yearly die back during the long dry season. There was no die-back in nursery raised irrigated seedlings.

    In the nursery A. quanzensis, B. microphylla, and J. globiflora seedlings were inoculated with mycorrhizal soil and basidiospores of fungi associated with adult trees. As a result of contact with soil inoculum, seedlings of these species formed ectomycorrhizae. only basidiospores of one fungus were able to form mycorrhizae with A. quanzensis in the nursery. In the field observations were made on seedlings of B. spiciformis and A. quanzensis naturally growing or artificially grown in the rhizosphere of their mother trees or other ectomycorrhizal miombo trees. Seedlings got colonised by fungi associated with adult trees. The infection started before germination was completed.

    Specificity ofAfzeliawas studied by inoculating seedlings with inoculum from other miombo tree species. Afzelia was found to have a broad host range.
    P. angolensis seedlings were raised in the nursery in the soil from the rhizosphere of adult trees of the same species. Seedlings of P. angolensis formed arbuscular mycorrhizae and nodulated. None of the ectomycorhizal legumes treated in this study nodulated.
    In the nursery the contribution of the mycorrhizal formation to the biomass accumulation was assessed for B. microphylla. Inoculated seedlings were far taller and had higher biomass than non-inoculated ones.
    The main features of miombo ectomycorrhizae is that they have many long and thick hyphae and big rhizomorphs. Rhizomorphs as big as 150 μm diameter were recorded.

    Fertilization in the nursery was done for P. angolensis seedlings. Simultaneous application of nitrogen and phosphorus boosted the growth. Nodulation was, however, eliminated on fertilized seedlings. Iron and zinc did not have any effect. In a nearby nursery, P. angolensis seedlings had iron deficiency symptoms and were dying. Application of iron solution on leaves had a visible effect within 2 days. At the end of the experiment, iron-treated seedlings had significantly grown in height, had produced new leaves and had developed their root system. Non-treated seedlings died or lost their leaves and had their root system very much shortened. In the greenhouse the same symptoms were experimentally reproduced by growing seedlings in compacted and overwatered soil.

    Mycorrhizal status of P. patula seedlings in various nurseries was assessed in Arusha, Mafiga and Sao Hill, Tanzania. Not all nurseries had mycorrhizae. As a result of lack of mycorrhizae, seedlings in Mafiga nursery were dying. After artificial inoculation, seedlings turned green and grew significantly. The control seedlings deteriorated. Inoculated seedlings formed mycorrhizae. More mycorrhizal types were found in Sao Hill compared to the other 2 regions. Suillus granulatus and Thelephora cf. terrestris were the most common mycorrhizae. The use of earthballs in nurseries instead of pots as practised on trial basis in one nursery, was found inhibitory to mycorrhizal development. Suillus was found sensitive to this practice. Earthballs have a high clay content and are poorly aerated.

    In Morogoro inoculation trials were conducted. Seedlings were grown in the pots in the greenhouse or directly raised under adult pine trees growing within 100 m from the greenhouse. Seedlings of the greenhouse received inoculum from those same adult trees. Seedlings under adult trees formed Suillus mycorrhizae of adult trees and were associated with sporophores of this fungi while those in the nursery formed Thelephora mycorrhizae and produced Thelephora sporocarps within 5 months. Thelephora sporocarp production stopped from the 6th month onwards while Suillus sporophores production continued under adult trees during the rain seasons. Infection was earlier and higher in the field than in the nursery.

    In the nursery pine seedlings were raised in fresh soil from the root zone of B.microphylla and Julbernardia globiflora. In the field seedlings were directly raised in the root zone of these miombo trees after addition or non-addition of pine mycorrhizal soil. A similar mycorrhizal type was formed in the nursery and in the field where no pine soil was added. Where pine soil addition was made, seedlings formed Thelephora mycorrhizae earlier observed in the nursery.

    The ecological strategies of miombo trees can be summarized in the following points. (1) The strategies focus on the underground compartment. (2) They are related to the architecture and dynamics of the root system with its deep and thick taproot. While the shoot in seedlings yearly dies back due to severe dry seasons, the taproot yearly expands. (3) The architecture with thin lateral roots lends itself to mycorrhizal formation and/or nodulation. Ectomycorrhizal legumes are of a broad host range. (4) Mycorrhizal lateral roots participate efficiently in building up the taproot, thus increasing the chances of seedlings to survive in dry and unpredictable environments. (5) The ability of seedlings and trees to develop new shoots using reserves drawn from the taproot towards the end of the dry season, allows them to efficiently use limited showers (6) Recognition of these facts is a basis for a successful afforestation with miombo trees.

    This research showed indeed that good nursery practices are beneficial for seedling growth and survival in the nursery and later in the field. The following points deserve attention in nursery management. These are (1) seed treatment (for P. angolensis ); (2) nutrient and moisture requirements; (3) (ecto)mycorrhiza; (4) restricted pruning of the taproot and (5) timing of activities.

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