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.

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    Potentie van onderstandige douglasverjonging: kleinschalig natuurvolgend bosbeheer
    Delforterie, W. ; Ouden, J. den - \ 2015
    Vakblad Natuur Bos Landschap 12 (2015)2. - ISSN 1572-7610 - p. 26 - 27.
    geïntegreerd bosbeheer - natuurlijke verjonging - pseudotsuga menziesii - prijzen (competitie) - onderzoek - integrated forest management - natural regeneration - pseudotsuga menziesii - prizes - research
    De douglas is vanwege zijn snelle groei en waardevolle hout een belangrijke bron van inkomsten voor veel boseigenaren. Doordat douglaszaailingen gemakkelijk opslaan onder een dicht kronendak en veel schaduw kunnen verdragen, komt onder volwassen gedunde douglasopstanden vaak al verjonging op van douglas. Deze verjonging kan het begin zijn van een volgende generatie bos, maar het is de vraag in hoeverre deze aanvankelijk onderdrukte ondergroei kan reageren op vrijstelling. Om meer inzicht te krijgen in de potenties van deze verjonging hebben wij onderzoek gedaan naar de groei van zaailingen van douglas onder scherm en de groeireactie van deze zaailingen na (gedeeltelijke) verwijdering van het kronendak.
    Disturbance Level Determines the Regeneration of Commercial Tree Species in the Eastern Amazon
    Schwartz, G. ; Lopes, J.C. ; Kanashiro, M. ; Mohren, G.M.J. ; Pena Claros, M. - \ 2014
    Biotropica 46 (2014)2. - ISSN 0006-3606 - p. 148 - 156.
    mahogany swietenia-macrophylla - bolivian tropical forest - reduced-impact - brazilian amazon - natural regeneration - logging damage - silvicultural treatments - carapa-guianensis - timber production - gaps
    The effects of reduced-impact logging (RIL) on the regeneration of commercial tree species were investigated, as long-term timber yields depend partly on the availability of seedlings in a managed forest. On four occasions during a 20-month period in the Tapajós National Forest (Eastern Amazon, Brazil), seven commercial tree species were assessed as follows: the long-lived pioneers Bagassa guianensis and Jacaranda copaia; the partially shade-tolerant Hymenaea courbaril, Dipteryx odorata, and Carapa guianensis; and the totally shade-tolerant Symphonia globulifera and Manilkara huberi. In 2439 10 × 10 m plots, all individuals <20 cm diameter at breast height (dbh) were assessed over three intervals, before, during, and after the forest being logged. Before logging, the density of seedlings and saplings of the seven species did not change. Logged trees were spatially aggregated, with 9.2 percent of the plots being heavily impacted by logging. After logging, the recruitment rate increased more than the mortality rate, so that post-harvesting densities of seedlings and saplings increased. The increase in density was concentrated in logged plots with more disturbances. It is concluded that post-harvesting heterogeneity of micro-environments created by RIL may be an important component to be taken into account for sustainable forest management and conservation of commercial species.
    Stimulating seedling growth in early stages of secondary forest succession: a modeling approach to guide tree liberation
    Kuijk, M. ; Anten, N.P.R. ; Oomen, R.J. ; Schieving, F. - \ 2014
    Frontiers in Plant Science 5 (2014). - ISSN 1664-462X - 13 p.
    natural regeneration - rain-forest - light interception - south kalimantan - carbon gain - costa-rica - canopy photosynthesis - subtropical forests - dipterocarp forest - tropical pasture
    Excessive growth of non-woody plants and shrubs on degraded lands can strongly hamper tree growth and thus secondary forest succession. A common method to accelerate succession, called liberation, involves opening up the vegetation canopy around young target trees. This can increase growth of target trees by reducing competition for light with neighboring plants. However, liberation has not always had the desired effect, likely due to differences in light requirement between tree species. Here we present a 3D-model, which calculates photosynthetic rate of individual trees in a vegetation stand. It enables us to examine how stature, crown structure, and physiological traits of target trees and characteristics of the surrounding vegetation together determine effects of light on tree growth. The model was applied to a liberation experiment conducted with three pioneer species in a young secondary forest in Vietnam. Species responded differently to the treatment depending on their height, crown structure and their shade-tolerance level. Model simulations revealed practical thresholds over which the tree growth response is heavily influenced by the height and density of surrounding vegetation and gap radius. There were strong correlations between calculated photosynthetic rates and observed growth: the model was well able to predict growth of trees in young forests and the effects of liberation there upon. Thus, our model serves as a useful tool to analyze light competition between young trees and surrounding vegetation and may help assess the potential effect of tree liberation.
    Mid-term effects of reduced-impact logging on the regeneration of seven tree commercial species in the Eastern Amazon
    Schwartz, G. ; Peña-Claros, M. ; Lopes, J.C.A. ; Mohren, G.M.J. ; Kanashiro, M. - \ 2012
    Forest Ecology and Management 274 (2012). - ISSN 0378-1127 - p. 116 - 125.
    bolivian tropical forest - brazilian amazon - natural regeneration - population-structure - carapa-guianensis - rain-forest - gaps - management - diversity - recovery
    Reduced-impact logging (RIL) is a set of techniques aimed to maintain forest structure and functions of the harvested forest as similar as possible to pre-logging status, while reducing adverse impacts from logging activity on the remaining forest. We analysed the mid-term effects of RIL on the regeneration of the long-lived pioneers (LLP) Bagassa guianensis and Jacaranda copaia; the partially shade tolerant (PST) Hymenaea courbaril, Dipteryx odorata, and Carapa guianensis and the total shade tolerant species (TST) Symphonia globulifera and Manilkara huberi. This study was carried out in an intensive study plot in the 600,000-ha Tapajós National Forest, Eastern Amazon – Brazil (03°02'S and 54°56'W). Three transects split in 10 × 10 m plots, adding up to 2.37 ha were sampled in an area where RIL was applied, and compared with a same size sampling in an unlogged area. The regeneration of individuals 20 cm in dbh was inventoried and measured before logging in 2003 and three times after logging (2004, 2006, and 2009). RIL modified the forest structure creating more gap-phase plots, with the consequences of such disturbance still remaining after 6 years. Densities of B. guianensis, J. copaia, and S. globulifera increased, while C. guianensis diminished. The positive effect on the density of LLP species was, however, ephemeral and disappeared 2 years after logging. RIL had a positive effect on the height growth rate of S. globulifera and on the dbh growth rate of C. guianensis. Plants growing in the gap-phase plots had higher height growth rates (ANOVA, F2;2980 = 33.3, p <0.001) than plants growing in other phases, but the same difference was not observed for dbh growth rates (ANOVA, F1;364 = 0.9, p = 0.33). Crown position had positive effects on height and dbh growth rates: the higher the crown position, the faster the plant grows in height (ANOVA, F3;2979 = 148.4, p <0.001) and dbh (ANOVA, F3;362 = 26.1, p <0.001). The application of RIL following the Brazilian regulations, may be considered a silvicultural technique for increasing density and growth rates of commercial species, but additional silvicultural interventions, as liberation for example, might be required for maintaining the ecological outcomes of RIL in the long run
    Soil organic carbon stocks and changes upon forest regeneration in East Kalimantan- Indonesia
    Yassir, I. - \ 2012
    Wageningen University. Promotor(en): Pavel Kabat, co-promotor(en): Peter Buurman; Bram van Putten. - S.l. : s.n. - ISBN 9789064645761 - 175
    natuurlijke verjonging - tropische bossen - imperata cylindrica - secundaire bossen - koolstofvastlegging in de bodem - organisch bodemmateriaal - bodemeigenschappen - vegetatie - plantensuccessie - kalimantan - indonesië - natural regeneration - tropical forests - imperata cylindrica - secondary forests - soil carbon sequestration - soil organic matter - soil properties - vegetation - ecological succession - kalimantan - indonesia

    Imperata grassland is a common vegetation type in Kalimantan (Indonesia), and other parts of South-East Asia. It indicates a high degree of degradation of the vegetation, and mostly occurs after slashing and burning of primary forest. Through secondary succession Imperata grassland is converted into new secondary forest and much of the original biodiversity is restored. The overall objective of the thesis was to study the regeneration of Imperata grasslands in East Kalimantan, and to measure the effects of regeneration on soil properties, with emphasis on the organic fraction. The research strategy was to compare plots of different regeneration stages, characterized by the period elapsed since the vegetation was last burned.
    Results show that during regeneration of Imperata grasslands, both vegetation composition and soil properties change, including chemistry of soil organic matter. Soil carbon stocks are higher under Imperata grasslands than under primary forest, and increase further upon natural regeneration of grassland to secondary forest. Highest carbon stocks are found in the later regeneration phases. Lower carbon stocks under primary forests are due to extremely low fertility, combined with shallow soils and low root mass in the topsoil. Root density as observed in the field is much higher under the grass vegetation. Results show as well that soil organic matter decomposition is most advanced under forest, as indicated by lower amounts of plant derived compounds and higher contribution of microbial matter. The results indicate that decomposition efficiency is related to soil organic matter chemistry, but more to abundance of N-compounds than to that of potentially recalcitrant compounds.
    In our case study, soil texture appears an important factor in the vegetation succession. On sandy soils, there is a strong increase with time of Pteridium aquilinum L., while the number of other species is lower. This slows down the development towards secondary forest. Canonical correspondence analysis (CCA) of environmental factors and vegetation show that pH, bulk density, sand and clay are the factors related to the distribution of species. The rapid secondary succession indicates that Imperata grasslands are not a final and stable stage of land degradation, but that frequent fires are necessary to maintain Imperata grasslands. If protected from fire and other intrusions such as shifting cultivation, Imperata grassland will readily develop into secondary forest. Imperata grasslands seem to be permanent because of human interference, especially through burning, and because so far few attempts have been made to sustainable rehabilitation.

    The influence of storm-induced microsites to tree regeneration patterns in boreal and hemiboreal forest
    Vodde, F. ; Jogiste, K. ; Kubota, Y. ; Kuuluvainen, T. ; Koster, K. ; Lukjanova, A. ; Metslaid, M. ; Yoshida, T. - \ 2011
    Journal of Forest Research 16 (2011)3. - ISSN 1341-6979 - p. 155 - 167.
    picea-abies forest - old-growth forest - experimental hurricane blowdown - intermediate wind disturbance - northern temperate forests - pinus-sylvestris forest - coarse woody debris - norway spruce - catastrophic windthrow - natural regeneration
    We reviewed studies dealing with regeneration under variable conditions in boreal and hemiboreal forests as affected by different microsite types by tree species functional groups. Generally, the importance of storm-induced microsites for regeneration dynamics in boreal forests depends on several factors: (1) distribution and type of microsites (generated by storm characteristics and stand conditions); (2) viable seed supply (stand history, species dispersal traits and status of surviving trees) and their species' life history strategy; (3) climatic and site conditions (pre-storm conditions and storm-induced changes); and (4) delayed storm effects, such as retarded falling of trees, favoured vegetation growth, etc. Studies acknowledging the significance of microsites were mostly related to intermediate or severe events, causing sufficient changes in resource levels and growth conditions, and influencing extrinsic factors such as frost heaving, erosion and browsing. Also, the dispersal traits of available tree species, including sprouting and response of surviving trees, such as canopy expansion, should be considered in evaluating microsite importance in individual cases. In intermediate to severe windstorm events, pioneer species are generally profiting most from the additional offer in microsites, requiring bare mineral soil and elevated locations for their establishment and growth. Under gap dynamics, shade-tolerant species benefit from dead wood and elevated locations as these offer safe sites in stands with abundant understorey vegetation.
    Limited Edge Effects Along a Burned-Unburned Bornean Forest Boundary Seven Years after Disturbance
    Slik, J.W.F. ; Beek, M. van; Bernard, C. ; Bongers, F. ; Breman, F.C. ; Cannon, C.H. ; Sidiyasa, K. - \ 2011
    Biotropica 43 (2011)3. - ISSN 0006-3606 - p. 288 - 298.
    tropical rain-forest - lowland dipterocarp forest - amazonian forest - wood density - seed-size - ecological attributes - natural regeneration - aboveground biomass - neotropical forests - light interception
    Large parts of the everwet tropics have been burned, leaving many unburned–burned forest edges. Here we studied a Bornean forest edge to determine: (1) how unburned and burned forest differ in vegetation structure, diversity, composition and plant functional traits 7 yr after fire, and (2) if these variables showed significant edge effects. Environmental and inventory data from 120 plots (0.01 ha each), covering both sides of a ~1.3 km forest boundary were sampled. Differences in vegetation structure, diversity, composition and plant functional traits were analyzed in relation to disturbance type (Mann–Whitney tests) and edge distance (partial correlation analysis that controlled for confounding effects of elevation, slope and fire intensity). Seven years after fire, burned forest differed significantly from unburned forest in most measured variables while few significant edge effects were detected, i.e., there existed a sharp delimitation between the two forest types. The regeneration of the burned forest depended almost entirely on in situ recruitment with little input of late successional species from the neighboring old growth forest. On the other hand, old growth forest showed few signs of edge degradation. A possible explanation for these results might be related to the absence of a mast fruiting event during these first 7 yr of forest recovery, resulting in low levels of late successional species seed input into the burned forest, combined with the quick development of a closed canopy in the burned forest by early successional species that shielded the unburned forest from adverse edge effects
    Ontwikkeling van gemengde natuurlijke bosverjonging : soortensamenstelling en kwaliteit op hoge zandgronden
    Oosterbaan, A. ; Berg, C.A. van den - \ 2011
    Wageningen : Alterra, Wageningen-UR (Alterra-rapport 2212) - 66
    bossen - natuurlijke verjonging - zandgronden - bosbeheer - inventarisaties - forests - natural regeneration - sandy soils - forest administration - inventories
    Om na te gaan of het in gemengde verjongingen voor de soortensamenstelling en de kwaliteit noodzakelijk is om in de eerste 15-25 jaar verzorgende maatregelen uit te voeren, is in 2010 een heropname verricht van een reeks natuurlijke verjongingen, waarvan de samenstelling en kwaliteit ook in 1996 is vastgelegd. Uit de analyse van de ontwikkeling van 66 verjongingen is gebleken dat de meeste verjongingen, zonder dat er maatregelen zijn uitgevoerd, nog steeds gemengd zijn met de soorten die vijftien jaar geleden aanwezig waren. Slechts in enkele gevallen is sprake van duidelijke ontmenging. Wat de soortensamenstelling betreft zijn dus in het algemeen geen maatregelen nodig geweest. Een uitzondering vormen o.a. de verjongingen waarin zomereik verdwenen is; deze had met gerichte verzorging gered kunnen worden. De kwaliteit van de verjongingen is in een kwart van de gevallen slecht, er komen (vrijwel) geen toekomstbomen in voor. Het is echter twijfelachtig of maatregelen in de jonge fase hadden kunnen zorgen voor een groter aantal toekomstbomen, omdat kromming in de stammen vaak het grote probleem is en het is de vraag of dit met maatregelen te voorkomen is
    A review of European ash (Fraxinus excelsior L.): implications for silviculture
    Dobrowolska, D. ; Hein, S. ; Oosterbaan, A. ; Wagner, S. ; Clark, J. ; Skovsgaard, J.P. - \ 2011
    Forestry 84 (2011)2. - ISSN 0015-752X - p. 133 - 148.
    acer-pseudoplatanus l. - north-temperate forests - beech fagus-sylvatica - natural regeneration - angustifolia vahl - broadleaved trees - site factors - fruit dispersal - ground flora - early growth
    European ash (Fraxinus excelsior L.) is common throughout much of Europe and is a valuable broadleaved tree due to its ecological characteristics, outstanding wood properties and high economic value. It is a fast growing species, associated with several forest types and with a scattered distribution in many different forest communities. In this review, we sum up essential characteristics of European ash, relevant to the further development of silvicultural practices. The paper covers site requirements, regeneration and stand establishment, growth dynamics and wood quality, and health and robustness. The review also highlights implications for silviculture and summarizes new information on ash dieback, a phenomenon which is observed in many European countries. Ash grows best on fertile, pH-neutral, deep, freely drained soils and such sites should be favoured if the aim is for high quality timber. Ash grows well at wide spacing which can result in enlarged ring width and increased latewood percentage, making the wood denser and stronger. Relatively short rotations may be recommended, depending on site, to avoid black heart: for example, a harvesting diameter of 60 cm can be reached within 60–75 years at 60–80 ash crop trees per ha. Universal recommendations are therefore for wide spacing with heavy, regular thinning in order to get a large diameter within a relatively short rotation. The necessity for pruning depends on the stand density at establishment and the subsequent thinning regime.
    Bottom-up versus top-down control of tree regeneration in the Bialowieza Primeval Forest, Poland
    Kuijper, D.P.J. ; Cromsigt, J.P.G.M. ; Jedrzejewska, B.A. ; Miscicki, S.C. ; Jedrzejewski, W.A. ; Kweczlich, I.C. - \ 2010
    Journal of Ecology 98 (2010)4. - ISSN 0022-0477 - p. 888 - 899.
    yellowstone-national-park - deer cervus-elaphus - white-tailed deer - red deer - primary productivity - predation risk - herbaceous vegetation - natural regeneration - capreolus-capreolus - plant-communities
    We tested the interactions between biotic and abiotic factors in structuring temperate forest communities by comparing tree recruitment after 7 years inside 30 pairs of exclosure (excluding ungulates: red deer, roe deer, bison, moose, wild boar) and control plots (7 × 7 m each) in one of the most natural forest systems in Europe, the Bialowieza Primeval Forest (eastern Poland). The strictly protected part of that forest hosts the complete native variety in trees, ungulates and their carnivores and excludes human intervention.2. We analysed whether the exclosure effect interacted with abiotic factors, relevant for tree recruitment (canopy cover, ground vegetation cover, soil fertility and soil wetness) at different stages of tree regeneration (seedlings, saplings = 50 and > 50 cm).3. Contrary to our expectations, a single factor dominated at each stage of tree regeneration. Herbaceous vegetation cover was the main factor determining the number of seedlings with an optimum at 38% of cover. Soil fertility determined the density of saplings = 50 cm, with on average three times higher density on eutrophic than on oligotrophic soils. Herbivory was the main factor determining recruitment rate of trees into > 50 cm size classes only.4. The density of saplings that grew into the > 50 cm size class was more than three times higher in the exclosures than in the control plots during 7 years. In the absence of ungulates, on average 3.1 species recruited into the > 50 cm size class compared to 1.7 in control plots. Tree species occurred in more equal proportions inside exclosures, whereas species composition was pushed towards strong dominance of a preferred forage species, Carpinus betulus, in the presence of ungulates. This suggests that preference of species by ungulates can coincide with tolerance to browsing.5. Synthesis. The study showed that abiotic conditions dominated the early stages and ungulate impact the later stages of tree regeneration, indicating the context-dependence of herbivore top-down effects. Heterogeneity in abiotic and biotic conditions may, therefore, have an important influence on the strength of top-down effects and the role that herbivores play in natural ecosystems.
    Effects of soil compaction and light on growth of Quercus pyrenaica Willd. (Fagaceae) seedlings
    Bejarano, M.D. ; Villar, R. ; Murillo, A.M. ; Quero Pérez, J.L. - \ 2010
    Soil & Tillage Research 110 (2010)1. - ISSN 0167-1987 - p. 108 - 114.
    biomass allocation - mediterranean oak - seed-mass - niche differentiation - natural regeneration - woody seedlings - root morphology - plant-growth - trade-offs - drought
    Soil compaction and light availability influence plant growth via different mechanisms. In general, soil compaction has a direct effect on roots, whereas light affects leaves and stems. Although plants in nature are exposed to variable levels of soil compaction and light, no study on the potential mutual interactions of these limiting factors in woody plants has to the authors' knowledge been reported to date. The aim of this work was therefore to elucidate the effects of soil compaction and light availability on growth and biomass allocation in the deciduous oak Quercus pyrenaica. To this end, a study was conducted at two light levels (viz. 3% and 100% of incident light, designated as low-light and high-light, respectively) under a wide range of soil compaction (0.02-3 MPa as penetration resistance) in a greenhouse. Total biomass was found to be positively affected by both light and soil compaction. There was marginally significant interaction between the effects of the two factors on total biomass, which was positively affected by soil compaction only under high-light conditions. Soil compaction had a strong, negative effect on the length of the main root; thus, at maximum soil compaction, such a length was roughly one-half that observed at lower compaction levels. Also, the specific root length of main root (root length to root mass ratio) was reduced by roughly one-half in highly compacted soils. These results suggest that an unfavourable combination of soil compaction and light availability may have severely adverse effects on woody plant performance in drought periods since plants with short roots can hardly access water at deep soil levels. The strength of this effect may be modulated by light availability.
    Verjonging in douglasbos neigt weer naar douglas
    Dekker, M. - \ 2009
    Vakblad Natuur Bos Landschap 2009 (2009)1. - ISSN 1572-7610 - p. 18 - 22.
    houtteelt - bossen - groei - gaten in het kroondak - natuurlijke verjonging - bosbedrijfsvoering - silviculture - forests - growth - canopy gaps - natural regeneration - forest management
    Het Nederlandse bos is nog steeds voor het grootste deel gelijkjarig en weinig gemengd, zo blijkt uit metingen over de periode 2001-2005 van het Meetnet Functievervulling Bos. Bosbeleid en -beheer zijn er al decennialang op gericht om de voormalige plantagebossen op een natuurgerichte wijze om te vormen en te beheren. In het bos kom je dan ook veel natuurlijke verjonging tegen die opkomt op plaatsen waar flinke gaten in het kronendak zijn gemaakt. Verjonging die vaak mooi gemengd is. De natuur doet zijn werk na een initiële beheersmaatregel; doel bereikt dus? Uit metingen aan verjongingen in een douglasmonoculture blijkt dat in eerste instantie berk, lariks en douglasspar het goed doen, en dat grove den het van het begin af moeilijk heeft. Op langere termijn neigt deze verjonging echter weer naar douglas, tenzij flink en vaak ingegrepen wordt.
    Tree Regeneration in Church Forests of Ethiopia: Effects of Microsites and Management
    Wassie Eshete, A. ; Sterck, F.J. ; Teketay, D. ; Bongers, F. - \ 2009
    Biotropica 41 (2009)1. - ISSN 0006-3606 - p. 110 - 119.
    tropical dry forest - alpine plant-communities - positive interactions - seedling establishment - natural regeneration - afromontane forests - juniperus-procera - northern ethiopia - statistics notes - rain-forest
    Tree regeneration is severely hampered in the fragmented afromontane forests of northern Ethiopia. We explored how trees regenerate in remnant forests along the gradient from open field, forest edge to closed sites and canopy gaps inside the forest. We investigated the effects of seed sowing, litter removal, and weeding on the regeneration success along this gradient. Regeneration success was investigated for four indigenous tree species, and measured in terms of seedling establishment, growth, and survival. Species performed differently according to site conditions. Within the forest, local canopy openings facilitated seed germination (Ekebergia), seedling growth (all species except Olea), or survival (Ekebergia and Olea), suggesting that all species benefited from local high light conditions in the forest. Outside the forest, germination (all species) and growth rates (Juniperus and Olea) were lower in the open field, most probably due to water stress in the dry season. Outer edge conditions favored growth for three of the four species. Natural seed germination was, however, zero at any site for Juniperus and Olea and low for Ekebergia and Prunus in the open field. Soil scarification influenced germination positively, while weeding did not have a positive effect. These results suggest that simple measures may improve seedling establishment, and that, for some species, forest edges are particularly useful for growth and survival after succesful establishment. Together with erecting fences, needed to protect seedlings against grazing, seed sowing, planting seedling, and soil scarification may contribute to maintain and restore church forests in the fragmented landscapes of northern Ethiopia
    Growth patterns, competition and coexistence in gap-phase regeneration under close-to-nature silviculture
    Dekker, M. - \ 2008
    Wageningen University. Promotor(en): Frits Mohren, co-promotor(en): Jan den Ouden. - [S.l.] : S.n. - ISBN 9789085049746 - 169
    houtteelt - verjonging - groei - natuurlijke verjonging - bosbedrijfsvoering - bossen - bosbouw - bosbeleid - gaten in het kroondak - europa - silviculture - regeneration - growth - natural regeneration - forest management - forests - forestry - forest policy - canopy gaps - europe
    The dominant European forest policy objective is to create multifunctional, mixed-species and uneven-aged forests. This objective includes the nature‐oriented conversion of monospecific plantations. To reach this objective, close-to-nature silviculture is applied. This generally entails natural regeneration in canopy gaps. In the Netherlands, experience with gap-phase regeneration is limited, making it difficult to asses the effect of close-to-nature management on forest development. In this thesis, this problem is addressed by investigating species coexistence between the four dominant species that occur in naturally regenerated canopy gaps in Douglas fir forest in the Netherlands. These species are Silver birch (Betula pendula Roth.), Japanese larch (Larix kaempferi Carr.), Scots pine (Pinus sylvestris L.) and Douglas fir (Pseudotsuga menziesii Mirb. Franco).
    During gap‐phase regeneration, saplings undergo self‐thinning. This affects species composition of the regeneration unit. Important factors in self‐thinning are species‐specific morphological growth patterns, emergent stand characteristics, the effect of stand characteristics on competitive relationships, and the effect of light availability on growth and mortality.
    Growth patterns differed between species and resulted in differences in the achieved height per unit biomass. Differences in mass‐based heights subsequently caused a vertical stratification in the regeneration unit which, in turn, affected the interspecific competition for light. However, results demonstrated a competitive response rather than a competitive effect. Surrounding saplings formed a functionally equivalent neighborhood, and target individuals responded mainly to their position in the canopy.
    Canopy position affected the radial growth of saplings. Mortality probabilities depended on radial growth, but did not differ between species despite a wide range in light demand. Scots pine did not show a relation between growth and mortality, even though it is highly responsive to light.
    Under continued autogenic development, a low-density top stratum of Silver birch and Japanese larch will develop, overtopping a declining number of Scots pine and a large number of increasingly dominant Douglas fir. This implies that Scots pine will be outcompeted by the other species, and Douglas fir will gain dominance in the future. Forest conversion by natural regeneration will therefore not lead to the desired mixed-species composition, but stands will eventually revert back to Douglas fir forest. Maintaining a diverse forest thus means the need for interventions in the early developmental stage.

    De spontane ontwikkeling van een jong bos op zeeklei (bosreservaat Hollandse Hout, Oostelijk Flevoland) : een analyse voorafgaand aan de aantakking van de Hollandse Hout op de Oostvaardersplassen
    Bijlsma, R.J. ; Verkaik, E. - \ 2008
    Wageningen : Alterra (Alterra-rapport 1615) - 49
    bossen - natuurlijke verjonging - verjonging - vegetatie - bosecologie - begrazing - plantensuccessie - zware kleigronden - zuidelijk flevoland - forests - natural regeneration - regeneration - vegetation - forest ecology - grazing - plant succession - clay soils - zuidelijk flevoland
    De spontane ontwikkeling in bosstructuur en vegetatie van bosreservaat Hollandse Hout bij Lelystad tussen 1995 en 2007 wordt besproken in het licht van de verwachte aantakking van de Hollandse Hout op de Oostvaardersplassen. De belangrijkste boomsoorten zijn es, esdoorn, eik en populier waarvan verjonging en sterfte zijn bepaald. De verjonging van es in relatie tot lichtbeschikbaarheid en het optreden van brandnetels en slakken wordt apart behandeld. De ontwikkeling van de bosflora wordt vergeleken met die in andere kleibossen in de polder en blijkt afhankelijk van paden en een heterogene bosstructuur. Tot slot worden prognoses voor de bosontwikkeling bij hoge graasdruk besproken, zoals verwacht na aantakking
    Regeneration of commercial tree species following silvicultural treatments in a moist tropical forest
    Peña Claros, M. ; Peters, E.M. ; Justiniano, J. ; Bongers, F.J.J.M. ; Blate, G. ; Fredericksen, T.S. ; Putz, F.E. - \ 2008
    Forest Ecology and Management 255 (2008)3-4. - ISSN 0378-1127 - p. 1283 - 1293.
    swietenia-macrophylla king - neotropical rain-forest - natural regeneration - soil disturbance - logging gaps - chimanes forest - eastern amazon - dry forest - bolivia - management
    Silvicultural treatments are generally performed to improve yields of commercially valuable tree species by increasing their recruitment and growth rates. In this study we analyze the effects of three different sets of silvicultural treatments on the densities and growth rates of seedlings, saplings and poles of 23 commercial tree species in a moist tropical forest in Bolivia. The treatments vary in intensity of logging and silviculture application, and are compared to a control treatment. Silvicultural treatments applied were liberation of future crop trees from lianas and neighboring competing trees, soil scarification and stand refinements. Treatments were applied to twelve 27-ha plots. In each plot 4 transects were established to assess the density and growth of the regeneration of the 23 commercial species. Effects were measured 1 and 4 years after treatment application and were described using three ecological guilds; shade-tolerant species, partially shade-tolerant species, and long-lived pioneers. We found that the intensive silviculture treatment had the largest impact on the density and growth rates of the regeneration of the commercial species. Overall, the density of regeneration of the commercial species was higher in the control treatment than in the logged treatments 1 year after treatment application, but 3 years later these differences had disappeared. Nevertheless, there were marked shifts in densities when different size classes were considered. In nearly all treatments, the number seedlings decreased over time, while the number of saplings and poles increased. Overall shade-tolerant species were more abundant than the other two ecological guilds. Treatment had a positive effect on density only for long-lived pioneers. Growth of commercial tree regeneration was strongly affected by treatment and was highest in the intensive silvicultural treatment plots where growth of long-lived pioneers was twice that of shade-tolerant species and partial shade-tolerant species. Apart from silvicultural treatments and ecological guild, light availability had the strongest effect on growth rates. These results show that different silvicultural treatments have different effects on the regeneration of commercial tree species and that ecological guilds-specific treatments should be considered in management plans for sustainable timber production in tropical lowland forests.
    Verjonging van jeneverbes (Juniperus communis L.) in het Nederlandse heide- en stuifzandlandschap
    Hommel, P.W.F.M. ; Griek, M. ; Haveman, R. ; Waal, R.W. de - \ 2007
    Ede : Directie Kennis, Ministerie van Landbouw, Natuur en Voedselkwaliteit (Rapport DK nr. 2007/dk072-O) - 44
    juniperus - struiken - natuurlijke verjonging - heidegebieden - eolische afzettingen - natura 2000 - juniperus - shrubs - natural regeneration - heathlands - aeolian deposits - natura 2000
    Dit obn onderzoek richt zich op de omstandigheden waaronder Jeneverbes zich in het Nederlandse heide- en stuifzandlandschap kan verjongen. Jeneverbesstruwelen vormen een karakteristiek onderdeel van de heide- en stuifzandlandschappen van onze pleistocene zandgronden. Zij hebben een grote cultuurhistorische waarde en herbergen tevens een hoge diversiteit aan soorten, met name aan paddenstoelen en levermossen. De afgelopen zestig jaar zijn in Nederland vrijwel geen zaailingen van Jeneverbes meer aangetroffen. Dit betekent dat de bestaande struwelen verouderen en op termijn zullen verdwijnen. Daarmee is niet alleen de toekomst van de soort in ons land onzeker geworden, maar treedt ook een groot verlies aan biodiversiteit op.
    Differences in regeneration between hurricane damaged and clear-cut mangrove stands 25 years after clearing
    Ferwerda, J.G. ; Ketner, P. ; McGuiness, K.A. - \ 2007
    Hydrobiologia 591 (2007)1. - ISSN 0018-8158 - p. 35 - 45.
    marina forsk vierh - avicennia-marina - rhizophora-apiculata - natural regeneration - seedling growth - predation - forest - salinity - establishment - propagules
    The effect of human disturbance on mangrove forest may be substantially different from the effects of natural disturbances. This paper describes differences in vegetation composition and structure of five vegetation types in two mangrove areas near Darwin, Australia, 25 years after disturbance. The vegetation in clear-felled forest showed more adult Avicennia marina than in the hurricane-affected forest, and a virtual absence of A. marina juveniles and saplings. This indicates that A. marina will be replaced by other species in the canopy, showing a multi-phase vegetation development in mangrove forest after human disturbance. The mechanism of disturbance and the conditions after clearing therefore affects the vegetation composition for at least 25 years after this disturbance took place.
    Natuurlijke bosverjonging op moeilijke plekken; een kwestie van lange adem?
    Oosterbaan, A. ; Berg, C.A. van den; Waal, R.W. de - \ 2007
    Vakblad Natuur Bos Landschap 4 (2007)2. - ISSN 1572-7610 - p. 26 - 27.
    bossen - bodem - ecologie - natuurlijke verjonging - forests - soil - ecology - natural regeneration
    Bossen worden tegenwoordig hoofdzakelijk verjongd door gebruik te maken van natuurlijke bezaaiing. Bosbeheerders krijgen langzamerhand steeds meer ervaring met deze manier van werken. In het algemeen is redelijk bekend welke factoren van belang zijn voor het slagen of ontbreken van verjonging: licht (gatgrootte), bodem (type en opbouw), vegetatie (samenstelling en bedekking) en wilddruk. Maatregelen als lichting, grondbewerking en bescherming tegen wild kunnen in de regel dan ook voor voldoende verjonging zorgen. Toch komt het voor dat natuurlijke verjonging ontbreekt, zonder dat er een directe oorzaak is aan te wijzen. In een verkennend onderzoek keek Alterra wat hier aan de hand kan zijn.
    Onderzoek naar oorzaken voor het ontbreken van natuurlijke verjonging
    Berg, C.A. van den; Oosterbaan, A. ; Waal, R.W. de - \ 2006
    Wageningen : Alterra (Alterra-rapport 1420) - 34
    bossen - bodem - zaden - natuurlijke verjonging - bosschade - wild - forests - soil - seeds - natural regeneration - forest damage - wildlife
    Natuurlijke verjonging wil op sommige plaatsen moeilijk van de grond komen. Een oriënterend veldonderzoek heeft opgeleverd dat licht, zaadbronnen en kieming wel voldoende lijken, maar dat de oorzaken meer in de richting van hoge wilddruk, dichte grasvegetaties en dikke, compacte, zure, onverteerde humuslagen in de bovengrond gezocht moeten worden
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