The following research on plant litterfall mass, dynamics, structure and chemistry was conducted from 2012 to 2014, on a 40- to 86-year-old stand of black alder (Alnus glutinosa) growing in a headwater area of the upper part of the valley of the Kamienna Creek (Middle Pomerania). Litterfall was collected every month with 20 circular traps, dried untill constant weight, divided into fractions, weighed and analyzed. The annual amount of litterfall deposited on soil during the study period ranged from 3482.5 to 4106.9 kg·ha-1, showing a dynamics pattern typical of temperate decidous forests. Leaves constituted the major fraction of litter with share of between 78.0 and 81.6% in its total mass. The contribution (in %) of twigs was 4.9-5.6, flowers 2.8-8.3, fruits 0.2-0.9 and other components 7.6-9.2. The relatively stable environmental conditions of headwater areas and the absence of disrupting factors during the study period were reflected in the low temporal variability of litterfall mass, dynamics and chemical composition of its individual fractions. The average annual pH of litterfall was 4.33-4.57. In general, litter was relatively rich in nitrogen and calcium but poor in phosphorus, potassium and magnesium. The content of Fe, Al and Mn was characteristic for these elements and low when compared to the other macroelements. The low contents of Cu and Zn confirm limited anthropogenic contamination of the investigated ecosystem with these metals. The annual return of the elements to the soil formed a series C>N>Ca>K>Mg>P>Mn>Fe>Al>Zn>Sr>Cu. A relatively large influx to the soil was noticed for nitrogen and calcium. Meanwhile, it was low for potassium, magnesium and phosphorus.

21.2.2016