March 2009

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English summaries

    • Scaling local nature restoration efforts up to landscape
    • W.C.E.P. Verberk, A.P. Grootjans & A.J.M. Jansen
    • Scaling up restoration efforts provides more opportunities for the restoration of large-scale processes (e.g. hydrology) and animal diversity. Restoration of large scale processes creates the necessary abiotic boundary conditions e.g. seepage and minero- and mesotrophic conditions. Furthermore, they are important drivers for landscape heterogeneity, involving gradients and mosaics; these are essential for most animal species, because they often use different habitats. To obtain the goal of restoring complete landscapes in the long term, without losing rare and threatened species in the short term, a combination of measures aiming at (1) the survival of species and (2) the restoration of processes is required. This means a thorough understanding of how species are currently dependant on local conditions for their survival and how restoration measures will cause suitable conditions to gradually shift towards the future situation (with its own functioning and spatial configuration). Switching between the local scale and the landscape scale is essential to make sure all species will be able to maintain populations during the process of restoration. This requires knowledge on both the biology of the species and the functioning of the landscape.

    • Key-factors and perspective for restoration of biodiversity in Southern Limburg
    • Nutrient-poor grasslands and forests on slopes, and brook valleys in Southern Limburg are potentially very rich in species and include both plant and animal species that are limited to these ecosystems. In 2008 the current state, bottlenecks and subjects for future research are described for brook valleys (Schaminée et al., in press) and forests on slopes (Bobbink et al., in press). The nutrient-poor grasslands on slopes have already been studied for several years with (field) research focussing on soil processes, plant and entomofauna diversity. First results clearly show that the current management in nature reserves is not optimal for full restoration of the biodiversity. Nutrients are not sufficiently removed, and the current management seems to conflict with the life cycle of characteristic entomofauna such as butterflies and ants. Furthermore, the extension of nutrient-poor grasslands is a big challenge, necessary for a sustainable survival of these species-rich and nutrient-poor grasslands on slopes.

    • From restoration of raised bogs and shallow softwater lakes to restoration of ‘complete’ wet landscapes in the Pleistocene district
    • G.A. van Duinen, E. Brouwer, A.J.M. Jansen, J.G.M. Roelofs & M.G.C. Schouten
    • To restore the biodiversity of wet landscapes in the Pleistocene district restoration of local and larger groundwater systems with the required water quality and water table fluctuation is in many areas a main task, next to reducing (the effects of) nitrogen deposition. Acid buffering, availability of carbon, and water table regime are key factors in the plant and animal species composition of softwater lakes and bogs. These factors are determined by the composition of the upper and deeper soil.
      In acidified and eutrophied softwater lakes the layer of organic matter sedimented on the formerly clean sandy bottom hampers the restoration of nutrient limited conditions required for recovery of typical vegetation and fauna. Organic matter removal is a successful and sustainable measure, as the nitrogen and sulphur deposition has been reduced considerably, provided that a (very) weakly buffered surface water quality is restored.
      Both bog landscapes and shallow softwater lakes are no homogeneous systems, but include mosaics and gradients in a.o. availability of carbon and minerals, acid buffering and vegetation structure. This environmental heterogeneity is a prerequisite for the conservation and restoration of the biodiversity of these systems, including typical and endangered species that depend on e.g. transitional mires and bog edges.
      The restoration of a complete plant and animal species spectrum of bog landscapes requires environmental heterogeneity on small and larger scales and influence of buffered ground water. The latter is also a key factor in the recovery of a Sphagnum dominated vegetation. A stable and high water table near the surface of the peat layer, as well as a high availability of carbon are maintained by a high table of buffered ground water in the basis of the remaining peat layer. Landscape ecological analyses of systems are necessary to assess the perspectives and proper measures for restoration of complete wet landscapes, including restoration of mosaics and gradients.

    • Recovering from long term effects of acidification and eutrophification in inland sandy landscapes
    • H. Siepel, H. Siebel, T.J. Verstrael, A.B. van den Burg & J.J. Vogels
    • Short term effects as increase of grasses were effectively beaten by sponsored management measures as large scale sod-cutting. Long term effects, however, are yet partly understood. The accumulative effect of acidification is also a complete wash-out of trace-elements in the soil, resulting in yet hardly recognized deficiencies in wildlife. An example of vitamin B2 deficiency in the Sparrowhawk is presented. Moreover, the excess of nitrogen leads also to shifted production of amino acids in plants, creating a hypothesized shortage of essential amino acids for wildlife. A cumulative effect in the food chain is to be expected. Restoration management, therefore, should aim at recovering of the basic buffer capacity of the soil and addition of trace-elements.

    • Perspectives for restoration of Dutch brook valley landscapes
    • C.J.S. Aggenbach, R.M. Bekker, U. Vegter & H.J. de Vries
    • Since two years the expert network for brook valley systems has widened her scope onto the restoration of complete landscapes. The expert network has started by formulating a research agenda based on the state-of-the art report called ‘pre-advies’. This yielded (1) a new classification system for the Dutch brook valley systems and (2) existing questions and lack of knowledge with regard to ecological restoration issues in brook valley systems became clear. This forms the starting point of our efforts to reinforce the natural quality of the brook valley landscapes in The Netherlands. New National and European directives like the Water Framework Directive and Natura2000 are implemented in the research agenda. The challenge of the network now focuses on studying the possibilities to recreate the conditions in which natural processes such as peat formation and inundation as well as keystone species belonging to the Dutch brook valley landscapes can thrive sustainably again.

    • Opportunities for further progress in restoring river-floodplain ecosystems
    • Anthropogenic modifications in river-floodplain ecosystems such as the construction of dikes, dams, groynes and weirs, the conversion of floodplains to agricultural land and water pollution have greatly reduced the spatial heterogeneity, as well as the variation in hydrodynamic conditions along the lateral gradient in the floodplain. Consequently, many riverine species have become rare and endangered. Ecological rehabilitation during the past 20 years has resulted in more than 8000 ha of new floodplain habitat along the branches of the Rhine and Meuse. Restoration of the entire hydrodynamic gradient will be the central research theme, given its importance for biodiversity. Research will focus on several parts along this lateral gradient. In Sedo-cerastion grasslands and alluvial forests research will focus on whether recovery is constrained by either dispersal limitation or unsuitable site conditions. Research on hydromorphology and biogeochemistry will aid in selecting sites with high potential for recovery. More knowledge will be gathered regarding the effects of grazing, both in the current situation and under more natural conditions. Research on riverine fish species will focus on their response to nature development measures. Riverine planning and management will need to take various aspects into account, including safety norms, opportunities for creating more space and the location of populations of rare and endangered species. This requires an approach on a landscape scale focussing on recreating the entire hydrodynamic gradient and increasing the spatial heterogeneity of hydrodynamic conditions.

    • Landscape scale conservation and restoration of fens
    • L.P.M. Lamers, W.C.E.P. Verberk, J. Schouwenaars, M. Klinge, W.J. Rip, J.T.A. Verhoeven & G. Kooijman
    • Fens represent an important part of the biodiversity and cultural-historic heritage of The Netherlands. The conservation and restoration of fens deserves high priority, both from a national and international point of view. The present paper highlights a number of important insights gained from the ongoing applied research on the restoration of aquatic and semi-terrestrial fens. We strongly emphasize the importance of studying biogeochemical and biological processes and factors responsible for the deterioration of plant and animal communities in fens. Effective restoration management requires a thorough understanding of the causal mechanisms underlying the process of degradation. Furthermore, knowledge of the key processes allows predictions to be made regarding the level of success. We propose to include the landscape scale both in research and in restoration measures, complementing the efforts that focus on local species biodiversity.

    • Ecological restoration from dune slack to coastal landscape
    • E.J. Lammerts, M. Nijssen, A.P. Grootjans, A.M. Kooijman & A.P. Oost
    • The Dutch coastal landscape originally hosted a high biodiversity. In the past decades the landscape has changed dramatically and biodiversity decreased. Eutrophication, acidification, desiccation, changes in land-use and a strong decrease in rabbit populations has led to grass and shrub encroachment. Aeolian dynamics are strongly decreased and the food web has changed, which is visible in the decrease of top predators. To restore the coastal ecosystem and its food web it is necessary to understand the mechanisms which influence natural processes on different temporal and spatial scales. A geo-ecological model of a Waddensea island is presented to analyse these different scales and to plan future restoration management. A combination of single, large scaled measures (where possible) and more frequent small scaled local management (where necessary) is seen as the best combination to restore the coastal landscape.

    • OBN and Natura 2000: natural partners
    • M. Fellinger, A.T.W. Eysink & P.C. van der Molen
    • Natura 2000 and the OBN-network are independently working on the same topic: preserving, maintaining and developing biodiversity in The Netherlands. The Provincial Authorities and three Dutch Ministries are in charge to provide management plans for all our Natura 2000 areas. However, these authorities are not involved in the OBN network. Though having the same aim and purpose, it is not self-evident that the Natura 2000 and the OBN networks meet each other.
      Both parties possess knowledge that is crucial for each other. The OBN network provides an enormous amount of knowledge on ecosystem functioning, field knowledge of Natura 2000 sites, and it operates in a multi-disciplinary approach with national expert teams. The Natura 2000 network offers result driven plans, focussed on complex ecological questions, in a complex process with Provinces, Ministries, Waterboards, landowners etc. The Natura 2000 network is dependent on available, ‘independent’ knowledge, which OBN can offer.
      The example of the Natura 2000 site Bargerveen shows the pay-off from the co-operation between these two networks. Final conclusion is that Natura 2000 and OBN are not just natural partners, but also essential partners.