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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    Fire ecology of Scots pine in Northwest Europe
    Hille, M.G. - \ 2006
    Wageningen University. Promotor(en): Frits Mohren; J.G. Goldammer. - [S.l. ] : S.n. - ISBN 9789085042839 - 179
    pinus sylvestris - brandecologie - bosbranden - biodiversiteit - bosecologie - plantensuccessie - europa - noordwest-europa - pinus sylvestris - fire ecology - forest fires - biodiversity - forest ecology - plant succession - europe - northwestern europe

    Keywords: biodiversity, fire ecology, fuel modelling, succession, tree regeneration

    In this thesis the ecological consequences of forest fire are studied in North-west European Scots pine {Pinus sylvestris) forests. The focus is on post-fire succession, and the factors and mechanisms that influence the successional pathways after fire. Fuel load and fuel moisture determine the intensity of forest fire and thus the degree of humus consumption. In a controlled laboratory' experiment humus consumption was determined for different moisture levels. Experimental fires showed evidence that variation in precipitation throughfall causes spatial variation in humus consumption in the stand through differences in humus moisture with respect to tree crowns. Humus consumption influences tree mortality, growth of remaining trees and re-colonization. Surface fires in Scots pine plantations caused a partial reduction of the litter and humus layers and a high mortality in the smaller trees. Reduction in radial growth after surface fire was variable, and was less in large diameter trees and in trees that experienced less humus consumption around their stem bases. Experimental burning of the humus layer showed that increased removal of organic material by fire resulted in an increase in seedling numbers. Earlier studies have suggested that the charcoal produced by fire improves germination conditions by absorbing phytotoxins produced by ericaceous species. All such studies have used activated carbon as a standardized model for charcoal. Bioassays with pine seeds in aqueous extracts of Vaccinium myrtillus and Calluna vulgaris showed toxic effects of the two species, but charcoal reduced toxicity less than activated carbon. Therefore, those previous studies have overestimated the effect of charcoal on germination, likely because of the considerably higher active surface area of activated carbon. The post-fire tree cohort after severe but small-scaled fires in Scots pine stands mainly consisted of Scots pine, but also birch and aspen. Compared to succession after other disturbance types in Scots pine stands, such as windthrow or soil scarification, seedling numbers are higher after small-scale fires by a magnitude often.

    Based on the good regeneration and for the purpose of fuel load reduction in areas with increased fire hazard, the prescribed burning of Scots pine stands should be reconsidered. Controlled forest fires could be used as an additional silvicultural technique to regenerate and transform single-species pine stands into mixed and more natural forests.

    Among rodents and rhinos: interplay between small mammals and large herbivores in a South African savanna
    Hagenah, N. - \ 2006
    Wageningen University. Promotor(en): Herbert Prins; H. Olff. - [S.l.] : S.n. - ISBN 9789085044673 - 138
    kleine zoogdieren - herbivoren - knaagdieren - rhinoceros - biodiversiteit - interacties - savannen - dierecologie - diergedrag - vegetatie - habitatselectie - brandecologie - zuid-afrika - small mammals - herbivores - rodents - rhinoceros - biodiversity - interactions - savannas - animal ecology - animal behaviour - vegetation - habitat selection - fire ecology - south africa
    Keywords:African savanna, biodiversity, Dichrostachys cinerea , different-sized herbivores, fire, herbivore interactions, murid rodents, spatial heterogeneity

    Mankind has caused species extinction of many groups of organisms through the transformation and fragmentation of once continuous natural habitats. In order to protect and restore natural biodiversity hotspots such as the African savannas we need to understand the determinants of their community structure and species diversity. Evidence has accumulated that body size differences that balance species facilitation and competition interactions as well as spatial heterogeneity may be key factors in the functioning of these ecosystems. This study explores the ecological consequence of the interplay between murid rodents and large herbivore species in a South African savanna and investigates the effect of abiotic factors on community interactions.

    The herbivores studied showed strong interactions that were influenced by both fire and rainfall. Exclusion of large herbivores resulted in plant species composition changes and grass cover modifications, leading to higher rodent abundances. Middle-sized and large herbivore species responded to short-term postfire succession patterns with large species being the pioneers on recently burnt vegetation patches. Both middle-sized and large species affect murid rodents in the time of recolonisation burnt areas, mostly through increasing and prolonging their predation risk via grass cover changes. Additionally, the grass cover played a major role in the habitat selection and space use of grass-eating rodents, although the availability of high quality food resources was also important, especially with male and females having different priorities. Furthermore, the recruitment of the encroaching woody species Dichrostachys cinerea was not only positively (less competition for water and light with grasses) and negatively (higher risk of being trampled or desiccation) affected by large herbivores and rainfall but also influenced through predation by invertebrates and murid rodents. The findings of this study suggest that herbivore communities from very small (murid rodents) to very large (elephant) potentially interact in a South African savanna and that this interplay is of importance for the maintainance of the biodiversity in these ecosystems. Large herbivores influence murid rodents mainly through top-down effects (via grass cover modifications) rather than through competitive and facilitative interactions for food (bottom-up). Additionally, by changing the vegetation structure large herbivores may have an impact on the woody species recruitment, but to what extent this imposes a feedback on them remains unclear. Furthermore, the study supports the hypothesis that herbivores, in interaction with abiotic factors, strongly modify African savanna ecosystems. Under low rainfall conditions woody species recruitment is mostly limited by seed predators and browsers, while fire plays a bigger role under high rainfall conditions. However, fire seems to be one possible management tool to maintain spatial heterogeneity in savannas in order to sustain coexistence opportunities for different-sized herbivore species.

    Effecten van brand in bos op arme zandgronden
    Meijer zu Schlochtern, M. ; Koop, H.G.J.M. - \ 2000
    Wageningen : Alterra (Alterra-rapport 160) - 93
    bossen - bosbranden - brandgevolgen - brandecologie - vegetatie - schimmels - zandgronden - nederland - brandgedrag - forests - forest fires - fire effects - fire ecology - vegetation - fungi - sandy soils - netherlands - fire behaviour
    Het rapport doet verslag van een onderzoek naar de directe en indirecte effecten van brand in bos op arme zandgronden. Voor de directe effecten is op een brandvlakte nabij Kootwijk kort na de brand in kaart gebracht waar grond-, loop- of kronenvuur heeft gewoed. Er is een relatie gelegd met de bosstructuur en het ontstaan van de verschillende soorten brand. Er is tevens een relatie gelegd tussen de vijf verschillende intensiteiten, die op basis van vlamhoogte zijn onderscheiden, en de overleving van de bomen en struiken in verschillende hoogteklassen. De indirecte effecten zijn onderzocht door vegetatie te onderzoeken op brandvlaktes van verschillende ouderdom. Deze vegetatieontwikkeling laat zien dat na een korte periode van verrijking, een verarming van nutri%nten te zien is. Pioniersoorten koloniseren de brandvlaktes, waarbij grondbewonende korstmossen weer veelvuldig aanwezig zijn.
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