Nutrient cycling in two continuous cover scenarios for forest conversion of pine plantations on sandy soil, II: nutrient cycling via throughfall deposition and seepage flux

This study examined ion throughfall deposition and seepage fluxes in silver birch (Betula pendula L.) and Scots pine (Pinus sylvestris L.) regenerations a decade after a forest conversion intervention in two continuous cover scenarios (shelterwood cut versus group cut), as well as a 70-year-old control stand of Scots pine. Ion throughfall deposition was significantly influenced by the conversion scenario, being higher in the shelterwood cut than in the group cut. Compared with the control stand, nitrogen and acidifying throughfall deposition was significantly lower (-60%) in all regeneration types except for the birch regeneration under shelter. After shelter removal, ion throughfall deposition was significantly lower in all regeneration types than in the control stand. Seepage of NO3- and SO42- was significantly affected by the tree species, being higher in the birch than the pine regenerations, and SO42- seepage was significantly higher under shelter than in the group cut. After shelter removal, neither tree species nor scenario influenced the SO42- seepage, whereas the tree species still affected NO3- seepage. We conclude that the chosen forest conversion scenario is of profound influence on the ion throughfall and seepage fluxes during the first phase of a forest conversion process.

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