Litterfall in a Scots Pine Forest on Inland Dunes in Central Europe: Mass, Seasonal Dynamics and Chemistry

Extensive areas of inland dunes are commonly overplanted with Scots pine (Pinus sylvestris). However, thus far the pine litterfall has not been investigated in detail in Scots pine stands overgrowing the landforms. Therefore, the aim of this study was to analyse the mass and chemical composition of litterfall in a dune Scots pine forest, paying special attention to the differences in the properties of the particular categories of litterfall (needles, twigs, bark, cones, residue) occurring in different seasons. The secondary goal of the research was to investigate the possible effect of contrasting slope aspect on litterfall properties. Litterfall was examined for three years on a north- and south-facing dune slope using the litter trap method. The mass and chemical composition (C, N, P, K, Mg, Mn, Ca, Fe, Al) of each litterfall category was analysed. Average annual mass of litterfall ranged from 322.0 ± 2.6 (slope N) to 361.9 ± 34.2 (slope S) g m−2 year−1. Fluctuations in the annual concentrations of N, P, K and Mg were determined, which was the result of their gradual withdrawal from needles before they were dropped in autumn. Immobile or poorly mobile elements (i.e., Mn, Ca, Fe and Al) were found to be steadily accumulated during the year in fallen tissues. The studied elements can be set in the following order as regards the annual pools which return to a topsoil with litterfall: C > N > Ca > K > Mg > Mn > Al > P > Fe on slope N and C > Ca > N > K > Mg > Al > P > Mn > Fe on slope S. Despite the fact that the residue (seeds etc.) constitutes a much smaller part of the total litterfall mass than the needles, comparable amounts of N, P, K, Al and Fe return to a topsoil with both these categories. The only element for which we determined differences in concentrations regarding slope aspect was Mn: the concentrations were significantly higher for needles, twigs, bark and cones on the N than the S slope.