March 2004

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English summaries

    • DVD bestellen A review of the start of ‘Plan Golden Plover’
    • Frentz, W.I.
    • In 1992 the Vereniging Natuurmonumenten initiated a strategy, called ‘Plan Golden Plover’, to develop a new natural area in The Mantingerveld, located in the Dutch province of Drenthe. The goal was to connect four existing small natural areas through the acquisition of 750 hectares of interspersed agricultural land parcels and their transformation into a natural area with heathlands, infertile grasslands, ephemeral ponds, scrub and forest. Excavation of the upper layer of the heavily fertilized soil was to ensure a return to the nutrient poor soils necessary for purposes of natural area development. Members of the Vereniging Natuurmonumenten were called upon to finance the project. Local residents neighbouring The Mantingerveld were not involved in the planning process, resulting in much resistance in the area. Currently (2003) a large part of the target area has been acquired. However, until recently the preconditions for natural area development (e.g., soil excavation) were hardly met due to some practical obstacles. For instance, local zoning (which is highly specific in the Netherlands) had to be adapted prior to the start of any work by the Vereniging Natuurmonumenten. Furthermore, it was very difficult to locate any clients for the upper soil layer that was to be hauled away. The soil appeared to contain soil diseases; it was prohibited to transport soil from some land parcels. For these reasons, the plans for meeting natural area development preconditions were eventually modified. In the mean time, the first results of natural area development are noticeable. For instance, birds such as the European Stonechat and Skylark have dramatically increased in numbers and several species of ground beetles have become established. In addition, the Vereniging Natuurmonumenten has made a considerable effort to create local support.
    • DVD bestellen The acquiring of arable land in the Project ‘Goldplover’
    • Leeuw, R. de
    • In the first half of 1900 large areas of heathlands in Drenthe were lost. In the past Vereniging Natuurmonumenten has tried to preserve parts of this original landscape. In Dwingeloo with succes (National Park Dwingelderveld), but in Mantingerveld only a few scattered hectares could be saved. The times were changing when the government accorded in 1990 her Nature Policy Plan to buy volunteerly 650 hectares arable land for nature conservation. In this way the isolated parts of heathland could be connected. This article shows the strong efforts of Vereniging Natuurmonumenten and her members to acquire the ground between the four still resisting heath parts; until now 475 of the 650 hectares could be acquired.
    • DVD bestellen Top-soil removal of former agricultural used soils: what is achieved after ten years?
    • Verhagen, R., R. van Diggelen & J.P. Bakker
    • To gain more knowledge about the opportunities top-soil removal of set-aside agricultural lands provides for the regeneration of low-production plant communities, an investigation was started in nine sites. The results show that removal of the top-soil results in a fast impoverishment of the soil. This provides good opportunities for the regeneration of low-production plant communities. Nitrogen becomes the limiting nutrient for the vegetation. Phosphate is influenced much less by top-soil removal. Over the first ten years after top-soil removal the amount of available nitrogen increases hardly in places where the top-soil has been removed entirely. Where part of the top-soil has left, the amount of available nitrogen increases faster. With all top-soil removed, the vegetation remains an open character during several years. Where part of the top-soil has been left, a high and dense vegetation develops within a few years. This will hamper the establishment of new species. Over ten years several characteristic species of nutrient-poor conditions have established in the sites. Especially the more common species of such conditions have established in several sites. Many rare and endangered species are absent, although several can be found in the direct vicinity of the study sites. This is the result of the low dispersal potential of most species. Both by wind and dung of large herbivores hardly any seeds of these species are transported to the former agricultural land. Therefore, additional management after top-soil removal should aim at remaining the low-productivity state and stimulate the transport of seeds of low-production plant species to the regeneration sites.
    • DVD bestellen Colonization of former arable land by butterflies after removal of topsoil;
    • Wallis de Vries, M.F. & S.H. Ens
    • The restoration of heathland and acid grasslands in the Netherlands is sometimes carried out by removing the topsoil from arable land, in order to lower the nutrient levels to those of the original environment. However, the establishment of target plant communities is fragmentary. The present study shows that this also applies to butterflies. In the eight study areas, ten years after topsoil removal, on average only two out of ten characteristic heathland species had recolonized the site, and then mostly at a lower density than in the source populations. Although isolation from source populations limited colonization, poor habitat quality, mainly due to lack of host plants, wet conditions and excessive residual nutrient levels, was the most important limiting factor. It can be concluded that habitat restoration by topsoil removal can be successful for butterflies of wetter heathland habitats, provided that source populations are nearby and care is taken to restore the habitat by, for example, introducing seeds of the original plant community
    • DVD bestellen Butterflies, dragonflies and grasshoppers do benefit from the Mantingerveld recovery plan
    • Bouwman, J., R. Ketelaar & R.J. Popken
    • The recent fauna of the Mantingerveld comprises 30 species of butterflies, 33 dragonflies and 13 grasshoppers. Characteristic species are Hipparchia semele, Plebeius argus, Hesperia comma, Lycaena tityrus, Satyrium ilicis, Lestes virens, Aeshna subarctica and Metrioptera brachyptera. The species composition is rather complete for a system with dry and moist heath and open sand with shallow oligotrophic lakes. Trends over the past ten years for butterflies of these habitats are generally positive, both for common and threatened species. Trends in grassland species are extremely negative, due to changes in the management of roadside verges. Traditional mowing and removal of hay has been abandoned which has resulted in eutrophication. Butterflies of forests and forest edges have also become rare, maybe due to the cutting of oaks in the central part. The converted agricultural land has been colonised by most common species. However, these ‘new’ natural habitats do not hold any characteristic and/or threatened species. Because these species are most vulnerable, the objectives of the recovery measures are not yet achieved.
    • DVD bestellen Birds do profit of the nature recovery plan in the Mantingerveld
    • Feenstra, H.
    • In 1993 just before the recovery measurements were taken there has been an investigation of all birds in the Mantingerveld. In 2002 this has been repeated: 94 species were observed. 6 species have disappeared and 17 species were new. Especially water birds like Tachybaptus ruficollis, podiceps nigricollis and Gallinago gallinago did profit of the new nature management, because several new lakes between Hullenzand and Lentsche Veen have been dug out. Also typical heath species benefit of the new circumstances: the numbers of Alauda arvensis, Anthus pratensis and Saxicola rubicola increased strongly. Connecting the little peaces who were left of what was once the ‘great, quite heath’ shows after ten years already good results for birds. However because of climate changing it still is doubtful if the Golden plover (Pluvialis apricaria) after which species the recovery plan in the beginning was called, will return.
    • DVD bestellen The importance of connecting isolated habitats illustrated at carabid populations;
    • Boer, P.J. den
    • To help solving persistent controverses and hot discussions around the regulation of animal numbers, survival of small populations and competition between species among ecologists in 1959 the author started from the Biological Station Wijster comparative, long-term investigations into the dynamics of carabid populations. He mainly concentrated his work at the large (1600 ha) heath area Dwingelderveld (Kraloërheath), where he discovered the principle of stabilization of numbers by ‘spreading the risk of local extinction’ over interaction groups (subpopulations) as an alternative for the more generally accepted idea of ‘regulation of animal numbers’. In this paper the author mentioned what happened with some of the carabid species he studied in the course of more than 40 years in this heath area under gradually changing environmental conditions (details in Den Boer & van Dijk, 1994) to show the importance of the ‘Plan Goudplevier’ of Natuurmonumenten for connecting isolated habitats.
    • DVD bestellen The Mantingerveld: effects of fragmentation and defragmentation followed using carabid beetles
    • Vermeulen, H.J.W., A.J. Spee & R.J. Popken
    • In 1958 the reclamations of heathlands and drift sands in the area of Mantingerveld (Netherlands, centre of province Drenthe) came to an end, leaving 300 ha of fragments scattered over this area. In 1992 several arable lands between those fragments were bought and restored by removal of the nutrient-rich topsoil layer. The effects of both fragmentation and defragmentation were followed by the Biological Station and compared to a large not fragmented area, the Dwingelderveld. Ground beetles were used as indicator species for the soil fauna. In 1959 at the Dwingelderveld and in 1963 at the Mantingerveld the first pitfall traps were placed; the sampling series were continued up till now. Although at both areas some species were lost due to overall working factors, in the Mantingerveld more species disappeared. After the restoration there was a slight growth in number of individuals in the fragments and some species were caught in the new areas. Also new heathland and drift sand species were caught. As the amount and quality of habitat increased, it is recommended to reintroduce the non-flying species or to introduce transplantates to give the entire poor dispersing soil fauna a chance.
    • DVD bestellen The antfauna of the Mantingerveld
    • Boer, P.
    • The ant fauna, ten years after topsoil removal on former agricultural soil, is very poor, even in the near vicinity of Calluna heathland. Successfull colonizing species were predominantly Lasius niger and to a lesser extent Myrmica sabuleti, while three other species were occasionally found. The ant diversity in the neighbouring heathland consists of 21 species. Active introduction by means of sod cutting of heathland, out of the direct environment is suggested. This may be an option to develop target communities, in which ants can develop and in which ants can help to develop this.
    • DVD bestellen Ten years after the start of 'Plan Golden plover'
    • Tooren, B.F. van, H.J.W. Vermeulen, R.J.H. Douwes & H.L. Schimmel - ten Kate
    • Ten years ago a plan was developed to connect four small nature reserves in the north of the Netherlands, mainly with heathland and woodland, by transforming the intensively used grassland between these reserves into heathland, extensively used grasslands and open water. Totally c. 650 hectares should be transformed into nature. Nowadays, 475 hectares new nature area has been achieved including 195 hectares where the nutrient rich top soil already has been removed. Main goals of the plan were to enhance the nature values of the existing nature reserves and to create more possibilities for dispersion of species between these nature reserves. A third goal was to develop interesting nature between the existing nature reserves. The main result after ten years is that many hectares of grassland, where large amounts of fertilizers were used and where large negative effects on the water table in the surroundings existed, has been transformed into a more natural area. There are indications that the value of the existing nature in the reserves is increasing, for example for birds and carabid beetles. Until now the new nature has invaded only slowly by most species, mainly because the development of the vegetation is rather slowly. Interestingly, there are large differences between different animal groups. Whereas carabid beetles are invading rapidly, ants avoid the new nature since the frequently still bare soil does not offer any comfort to these species. Also rare plant species invade the newly created nature only very slowly, probably due to the absence of seeds of these species in the soil and the poor dispersal capacities of most species. More time is needed to obtain sufficient dispersal possibilities for many species.