32 research outputs found

    Former land use affects the nitrogen and phosphorus concentrations and biomass of forest herbs

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    The colonization rates of understorey plants into forests growing on former agricultural land differ remarkably among species. Different dispersal and recruitment largely account for the contrasting colonization rates, but different effects of the soil legacies of former agricultural land use on plant performance may also play a role. Seven herbaceous forest species were sampled in paired post-agricultural and ancient forest stands to study whether land-use history has an effect on the aboveground nutrient concentrations (N, P and N:P ratios) and biomass of forest herbs and, if so, whether slow and fast colonizing species respond differently. Results showed that P concentrations were significantly affected by former land use with higher concentrations in the post-agricultural stands. N concentrations were unaffected and N:P ratios were significantly higher in the ancient stands. Nutrient concentrations varied considerably among species, but the variation was unrelated to their colonization capacity. Six out of the seven species had higher biomass in the post-agricultural stands relative to the ancient stands, and the degree to which the species increased biomass was positively related to their colonization capacity, i.e., the fast colonizing species showed the strongest increase. Such differential responses to past land use may contribute to the contrasting colonization capacity of forest plants. Land-use history thus affected both the nutrient concentrations and biomass of forest herbs, and only the biomass response was related to colonization capacity

    Veranderingen in bodem- en strooiselkenmerken bij de omvorming van gemengd loofhout naar fijnspar

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    Het is al langer bekend dat diverse bodemkarakteristieken een invloed hebben op de vegetatie. Recenter werd duidelijk dat bodem, bodemorganismen, strooisel en vegetatie als samenhangende componenten van een ecosysteem moeten gezien worden. Wanneer we ingrijpen in één van deze componenten kan dit leiden tot grote veranderingen in het ecosysteem. In deze studie wordt gekeken naar de impact van omvorming van loofhout naar naaldhout op de strooisellaag, bodem en bodemorganismen. De effecten van boomsoorten op de bodem werden al vrij goed onderzocht. Onderzoek naar de trajecten van veranderingen langsheen een bodemgradiënt zijn echter beperkt. In deze studie wordt het effect van een verandering van boomsoort op de humus-, kruidlaag en regenwormengemeenschap onderzocht langs een natuurlijke gradiënt van zuurbufferend vermogen. Dit onderzoek vindt plaats in het bossencomplex boven Virton in de Gaume-streek (zuid-België). Door verschillen in moedermateriaal en bodemtextuur is er een natuurlijke gradiënt van zuurbufferend vermogen aanwezig. In deze oude loofbossen werden sinds de jaren ’50 eilandjes fijnspar aangeplant. We vergeleken de fijnsparbestanden paarsgewijs met de aanpalende loofbestanden. In elk bestand werden de strooisellaag, bodemchemische eigenschappen en de regenwormengemeenschap opgemeten. De bodem in de fijnsparbestanden was duidelijk zuurder dan in de gepaarde loofbestanden. Ook de concentratie van basische kationen, de kationenuitwisselingscapaciteit (CEC) en baseverzadiging (BS) waren lager terwijl de Aluminium-concentratie (Al) steeg. De strooisellaag in de naaldbestanden was beduidend dikker dan in de loofbestanden en de regenwormengemeenschap was kleiner geworden. Opvallend was dat de verschillen tussen loof en naald groter waren op de rijkere bodemtypes. Het wegvallen van de bodemwoelende regenwormen in de fijnsparbestanden op rijkere bodems heeft er gezorgd voor een ware ecosysteemshift, gekenmerkt door een sterke strooiselaccumulatie en verzuring van de bodem

    Habitat preferences of European nightjars caprimulgus europaeus in forests on sandy soils

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    Capsule Nightjars prefer open places in younger forest areas, and open stands with wide forest tracks in older forest areas. Aims European Nightjars are a Species of European Conservation Concern (historical declines in both population and range). The reduction of heathland habitats means that forested areas are an increasingly important habitat for Nightjars. However, the ecology of Nightjars in forested areas is poorly understood. We set out to investigate Nightjar habitat preferences in a 5000-ha forest landscape in northern Belgium. Methods Calling ‘churring’ males were counted in each year over ten years. Habitat descriptors were derived from detailed habitat mapping based on aerial photographs and extensive field surveys. The different habitat descriptors were compared between patches occupied by Nightjars and control patches (patches selected at random in the study area). Results As expected, Nightjars showed a preference for open places in younger forest areas (clearfelled areas, young stands, windfall and permanent open places). They also showed a preference for old and open stands that had wide forest tracks. Forest type appeared not to be significant. Heath, bare sand and, to a lesser extent, leaf litter have an increased presence in patches used by Nightjars. Conclusion For the conservation of Nightjars, we suggest that open places within larger forests should be created. Also a network of wide forest tracks can make smaller patches suitable for Nightjars. Patches of bare sand should be created or maintained
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