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

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

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

Large potential steps at weakly interacting metal-insulator interfaces

Potential steps exceeding 1 eV are regularly formed at metal|insulator interfaces, even when the interaction between the materials at the interface is weak physisorption. From first-principles calculations on metal|h-BN interfaces we show that these potential steps are only indirectly sensitive to the interface bonding through the dependence of the binding energy curves on the van der Waals interaction. Exchange repulsion forms the main contribution to the interface potential step in the weakly interacting regime, which we show with a simple model based upon a symmetrized product of metal and h-BN wave functions. In the strongly interacting regime, the interface potential step is reduced by chemical bonding

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

Band gaps in incommensurable graphene on hexagonal boron nitride

Devising ways of opening a band gap in graphene to make charge-carrier masses finite is essential for many applications. Recent experiments with graphene on hexagonal boron nitride (h-BN) offer tantalizing hints that the weak interaction with the substrate is sufficient to open a gap, in contradiction of earlier findings. Using many-body perturbation theory, we find that the small observed gap is what remains after a much larger underlying quasiparticle gap is suppressed by incommensurability. The sensitivity of this suppression to a small modulation of the distance separating graphene from the substrate suggests ways of exposing the larger underlying gap

Schottky barriers at hexagonal boron nitride/metal interfaces: a first principles study

The formation of a Schottky barrier at the interface between a metal and hexagonal boron nitride (h-BN) is studied using density functional theory. For metals whose work functions range from 4.2 to 6.0 eV, we find Schottky barrier heights for holes between 1.2 and 2.3 eV. A central role in determining the Schottky barrier height is played by a potential step of between 0.4 and 1.8 eV that is formed at the metal|h-BN interface and effectively lowers the metal work function. If h-BN is physisorbed, as is the case on fcc Cu, Al, Au, Ag and Pt(111) substrates, the interface potential step is described well by a universal function that depends only on the distance separating h-BN from the metal surface. The interface potential step is largest when h-BN is chemisorbed, which is the case for hcp Co and Ti (0001) and for fcc Ni and Pd (111) substrates

Beheersplanning voor staatsnatuurreservaten

Na een knelpuntenanalyse worden mogelijke verbeteringen binnen de planningsprocedure en planinhoud voorgestel