EN
The effect of contrasting meteorological conditions on hydrology, hydrochemistry and input–output budgets of nutrients and metals was examined in a small (2.8 ha) forested watershed of the Masurian Lakeland (NE Poland). The conditions of a frosty and dry continental winter activated an outflow of underground water originating from deeper water resources. The chemical composition of this outflow differed from watershed waters outflowing during mild winters with respect to SO4-S, Ca and Mg, which had lower concentrations, and NH4-N and K, which exhibited higher concentrations. An exceptionally severe winter affected also element fluxes in the examined watershed during the subsequent growing season. In order to show this impact, a comparison was made between the balances of elements moving through the investigated forest ecosystem during the growing seasons following mild and extremely cold winters. A biogeochemical effect of a frosty winter drought in a small post-glacial forested watershed, observed during vegetation growth (April – October), involved increased mineralization of nitrogen and phosphorus: a higher level of DON and DOP retention and a lower level of SRP and NO3-N retention. The increase in mineralization and the “opening” of biogeochemical cycles were also reflected in the loss of metals as K, Na, Ca and Mg.