178 research outputs found
Feasibility
Extensive livestock farming, including hay making, seems the most feasible management strategy for open peatland. In the longer term, wilderness grazing may become more feasible. The loss of economic viability of traditional livestock farming and related haymaking may be reversed by innovation of new marketable 'Biebrza' products, 'green services', e.g. eco- and agro-tourism, and by financial subventions by the EU and the Polish Government. Large scale mechanical harvesting of hay and litter is very costly, unless the harvested hay can be marketed. The feasibility of New Wilderness, especially complemented Wilderness, may increase in the longer term. The BNP offers excellent perspectives for a growing role of wild herbivores and natural processes. An eventual step-by-step transition may pass through stages with increased densities of elk, red deer, and wild boar, (semi-) feralisation of Konik ponies, re-introduction of European Bison and finally (semi-) feralisation of cattle. New Wilderness in an enlarged 'Greater Biebrza Ecosystem' will create a unique, complete ecosystem in Europe, with large economic potential
Introduction
The biodiversity of low-productive pastures and hayfields is threatened across Europe by intensified land use and abandonment. The question is whether and how Extensive Farming can be maintained or restored, or whether conservation management should shift to New Wilderness. Suitability and feasibility of both strategies differ and depend on local conditions. The aim of the workshop was to discuss and clarify the strategic management dilemma for peatlands by taking the Biebrza National Park (BNP) in N.E.Poland as a case study. The BNP authorities are facing a tremendous and difficult problem to stop and reverse succession on 20.000 ha abandoned fen peat. Questions addressed during the workshop were 'Which extensive farming methods (grazing, mowing, cutting, and burning) are suitable for BNP-peatlands in view of the management objectives? Which methods are most feasible in view of the actual and future socio-economical environment of the BNP? Which management recommendation and research recommendations can be given to the BNP authorities
Management recommendations
The acute succession problem justifies an opportunistic use of all suitable methods on the short-term (10 years). The ban on winter burning should be (temporally) lifted. The mown area should be enlarged by activating volunteers, raising budgets and funds for mowing of BNP-owned peatlands and by using peat harvesters. BNP and farmers should co-operate to raise funds and conclude Management Agreements for livestock farming on private and BNP-owned peatland. Agreements should include the use of Biebrza hay and litter. In the longer term (>10 years) extensive grazing seems the most promising tool. It may be implemented as traditional dairy farming, ranching of beef cattle, horses or (semi-) wild herbivores or as Wilderness. Suitability and feasibility may differ between the three basins. The entry of Poland to the EU will affect the feasibility of the strategie
Suitability
The suitability of grazing, burning, mowing and cutting as tools for succession control in peatland was assessed and expressed on a scale from 0 - 1. All management tools are suitable, but their effects are conditional. The suitability depends on the targeted vegetation transition and on their intensity and timing. Maintenance and restoration of short vegetation requires an annual or short cyclic (2-5 years) removal of the major portion of the aboveground annual production during the growing season. Grazers, Intermediate Feeders, Browsers and mechanical removal (including burning) fulfil a complementary role. Taking a suitability value of >0.66 as criterion, a complete herbivore assemblage at saturation density might realise all objectives, except regression from Alder to short vegetation. This requires cutting. Lacking herbivory may be substituted by removal by man or by fire. Suppression of invading shrub by winter burning requires sufficient inflammable biomass. Winter burning cannot substitute the effects of summer grazing on tall sedges and Reed. Burning in late winter may damage early shoots of sedges and Bush gras
Historische analyse van de Zeeschelde en haar getijgebonden zijrivieren: 19e eeuw tot heden
The River Scheldt currently has a macrotidal estuary with a tidal reach of 160km. It covers a complete salinity gradient with a polyhaline, mesohaline and oligohaline zone and a fresh water part with long and short retention time of chloride. The estuary and its tidal tributaries Durme and Rupel have been heavily influenced by anthropogenic pressures such as land reclamation, harbour expansion, dredging activities, embankments and urbanisation. A good understanding of the impact of human interventions on the ecological functioning of the estuarine ecosystem is required. Based on this knowledge appropriate compensation or mitigation measures can be taken in response or anticipation to future negative effects of anthropogenic changes and relative sea level rise. In this study, all available data on tidal regime (1850-2000), bathymetric charts (1930, 1950, 1960, 1970, 1980, 1990, 2000) historical maps from the beginning of the 19th century onwards and aerial photographs from 1944 onwards were compiled and analysed for the Zeeschelde (Belgian part of the Scheldt estuary) and the tidal tributary river sections.The report deals with three main issues:(1) Ecological changes during the past century are analysed using a hierarchical ecotope approach.The evolution of the acreage of the distinguished physiotopes (physically characterised units) andecotopes such as shallow waters, tidal mudflats and marshes are analysed for each salinity zone or river section;(2) Changes in hydrodynamic and morphological parameters are analysed over the past century;(3) An overview of anthropogenic interventions and natural changes with potential effects onhabitat acreage and quality in the Zeeschelde and its tidal tributaries in the past two centuries. Thenature of the interventions is very diverse: reclamations, diking, land use change, infrastructureworks, dredging activities, canalisations, discharge manipulations and changes in river dynamics.Changes in tidal regimeBecause tidal regime is a key factor in an estuarine ecosystem, we analysed the characteristics ofthe ten year mean high water (MHW), mean low water (MLW), tidal asymmetry and the tidalamplitude. Temporal and spatial patterns of these parameters are examined within differentsalinity zones in the Scheldt, the Durme and the Rupel.MHW shows a gradual increase in the whole Scheldt estuary. The highest rise is located in the freshwater part with short retention time. Maximum MHW shifted 32km upstream from Antwerp to Sint-Amands within one century.MLW and tidal asymmetry show a more irregular pattern and are more sensitive to anthropogenicactivities such as dredging and deepening in the navigation channel. MLW dropped in the pastcentury in the harbour zone of the Scheldt between the Dutch-Belgian border and the confluence ofthe Rupel and along the Rupel. In the fresh water zone with long retention time, MLW and tidalasymmetry changed little till 1970 (1st deepening of the Scheldt). After this period MLW strongly dropped as in most other river sections. MLW and tidal asymmetry in the fresh water zone with short retention time increased between 1900 and 1970 and were presumably affected by river discharge reductions and canalisations. After the 70’s MLW and tidal asymmetry decreased again. In the Durme MLW dropped at the confluence, more upstream it rised because of sedimentation in the riverbed. Discharge deviation, damming and channel straighthening played an important role here as well. At the same time tidal asymmetry increased in the whole Durme.MHW and MLW changes resulted in a high increase of tidal amplitude in the Scheldt and Rupel. In the River Scheldt the highest tidal amplitude was recorded at Lillo (62km to North Sea) around 1890, while in the last ten years the maximum occurs in Temse (98km to Sea); a shift of 36km upstream in a bit more than a century. In the Rupel the amplitude increased overall in time but less so in the upstream part. The Durme has an irreg
Schorecotopen van de Schelde : Aanzet tot de ontwikkeling van één schorecotopenstelsel voor Vlaanderen en Nederland
Inventarisatie en historische analyse van Zeescheldehabitats (vervolgstudie). Resultaten van het eerste jaar
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