3. Management Recommendations near Wetlands

Wetland management in forests is part of the protection and enhancement measures of biodiversity and water resources, whereby two main goals are paramount:

  • It is essential to preserve an optimal level of semi-naturalness: i.e. encroachments to the recreation and restoration of affected biotopes have to be limited
  • The functionality of wetlands must be maintained or if necessary recreated: i.e. interventions which could disrupt the functioning of these biotopes are to stopped. Wetlands fulfil important ecological functions in the upper reaches of catchments, they must be preserved and enhanced.

Maintaining and recreating wetland functionality

Goal: Wetlands are characterised by their close connection to water. Changes to the water supply and the hydromorphic characteristics of these habitats can directly endanger their continued existence. The functionality of a wetland must therefore be safeguarded at the scale of its water catchment and not be limited to just the wetland itself.

Management measures

  • Close still active drainage channels through simple means so that they rehabilitate back into the landscape well;
  • Support the snowmelt retention function of natural wetlands, especially near machinery lanes and forest roads;
  • No infilling or working near wetlands which could lead to a reduction in the size of the wetland and/or an increased desiccation of these habitats;
  • In certain cases appropriate management is necessary to counteract siltation of the natural water surface (tarns etc.);
  • In wetlands with poorly positioned cover, sudden changes to the plant cover must be avoided so a protective climatic balance can be kept. (I.e. don’t completely remove the tree or herb layer of wetlands);

A differentiated forest management

Goal: From a silviculture perspective it is important to maintain and enhance natural forests suited to wetlands and to sustain a diversified, multilayered margin (shrub layer and especially tree species which allow light penetration). Apart from the natural habitats of pine-spruce forests and moor-Scotch Pine forests, it is very important to reduce the pressure of allochthonous spruce forests (Spruce, Douglas Pine, Weymouth-Scotch Pine etc.)

Silviculture measures

  • Reduce allochthonous species surrounding or directly next to wetlands in favour of appropriate open-space tree species
  • Where there is heavy browsing it is appropriate to intervene to avoid favouritism leading to spruce stand development;
  • Possible enrichment through plantings (to enhance the species variety); however leave as much as possible to natural rejuvenation;
  • Undertake scarification on mulch beneath spruce forest stands to enhance rejuvenation of Black Alder (e.g. Alder and Alder-Ash forests in valley bottoms);
  • Specific measures on the margins to reduce the pressure from allochthonous tree species;

Wetland compatible timber harvesting

  • Use biodegradable oils when harvesting in or on the edge of wetlands;
  • No machine storage in wetlands or directly surrounding wetlands;
  • Use timber harvesting methods suited to the requirements of wetlands: no machine traffic in the wetland, remove timber completely to avoid forest slash being left behind, no timber storage in wetlands

Control of invasive, exotic plants in wetlands

Goal: Maintenance or recreation of semi-natural habitats

Management measures: At the moment forests are keeping the impacts of invasive plants under control, however preventative measures should be considered in forest wetlands to prevent the spread of invasive plant species.

  • Keep a continuous crown canopy: no extensive and sudden opening up of the stand in already affected areas or in areas that are near zones where exotic plant species are found;
  • Avoid stockpiling or introducing foreign material that could contain plant seeds;
  • Clean forest machinery before and after working in the forest;
  • Regularly undertake hay-making (2x a year or more often during vegetative growth periods) with subsequent removal of plant material (with destruction outside of the forest) in areas in to which invasive plants have only recently, or sparsely, spread;

Article series: Cartographic survey of water bodies in the Vosges and Alsatian Jura mountain ranges by the ONF.