Leaf litter fall decomposition in age-differentiated stands of poplar clone 'Hybrid 275'.

摘要

The aim of the study was to compare the process of leaves decomposition in three stands of poplar 'Hybrid 275' [Populus (maximowiczii x trichocarpa) cv. Hybrid 275] in different age. The study was conducted in 2000-2002 at 17 (17Y), 28 (28Y) and 54 years old (54Y) plantations in northern Poland, forest districts Wierzbiczany, Gronowo, Ostromecko. Studies were conducted using 30 cm x 30 cm litter bags made of 1 mm mesh nylon netting, filled with 15 g of dry leaves collected in the autumn of 2000. Every two months one bag was collected from each point. The material was dried at 65 degrees C, weighed and analysed. The process of leaves decomposition was fastest in the 54 years old stand, slightly slower in the 28 years old stand and slowest in the 17 years old stand. After 12 months in the 54Y stand almost 80% of the initial mass was decomposed, in the youngest stand it was slightly more than 40%. The coefficients of decomposition, based on Olson's model, were 1.49 for 54 years old plantation, 0.97 for 28 years old plantation and 0.61 for 17 years old plantation. Because the temperature and humidity conditions were similar at all stands, the different rate of decomposition can be attributed to different chemical composition of the initial material. Different chemical composition of leaves can be the effect of different age of poplars. Distinct differences were noted between the plantations in the content of phosphorus, potassium and magnesium. Only small differences were observed in the nitrogen content and C/N ratio, which excludes these as differentiating factors. Lignin content was correlated with the age of poplars, with their proportion decreasing with the age of trees.