Patterns of throughfall deposition along a transect in forest edges of silver birch and Corsican pine

Abstract

In two adjacent forest stands in Flanders, one dominated by Corsican pine ( Pinus nigra subsp. laricio Maire) and another dominated by silver birch ( Betula pendula Roth), throughfall deposition was monitored along a transect perpendicular to the forest edge exposed to the prevailing wind direction. Throughfall deposition of Na+, K+, Ca2+, Mg2+, NH4+, NO3–, Cl–, and SO42–was examined on forest edge patterns expressed in the depth of influence of the edge effect (forest edge distance) and the level of enhancement at the edge (forest edge enhancement). In addition, an integrated forest edge enhancement factor was computed that incorporates these two parameters. Our results show that the edge effects on throughfall deposition of Na+, Cl–, the sum of so-called base cations, the sum of potentially acidifying ions, and the sum of inorganic nitrogen (NH4+ + NO3–) are more pronounced in the pine stand. The edge zone of the pine stand receives as a result of the edge effect 9.4 times more extra potentially acidifying ions and 12.7 times more extra inorganic nitrogen than the birch stand. We conclude that an appropriate design or conversion of the edge structure, from high-density Corsican pine plantations into lower density deciduous forests, can reduce the input of acidifying and eutrophying pollutants in the forest edge.