Litterfall collectors

20 litter collectors (diameter 60 cm) and 20 branch collectors (100 x 50 cm) are installed in the catchments (Ilvesniemi et al., 2009; Korhonen et al., 2013). Samples are collected monthly. The samples are dried in 60°C for 24 h weighed. Dried litter is separeted into needles, leaves, bark, branches, seeds (including cones) and the rest. Each compartment is weighed, ground and pooled. Carbon and nitrogen concentrations are measured from the pooled samples by elemental CN-analyzer (LECO, Leco Corporation, St. Joseph, MI, USA).