Decomposition rates of Scots pine needle litter related to site properties, litter quality, and climate

Decomposition of Scots pine (Pinussylvestris L.) needle litter was studied at 14 sites along a climatic transect through Sweden. The forests encompassed a wide range of the variability in site properties found in the country. The mass loss pattern of litter differed considerably among sites. Mass losses obtained during the 1st year of decomposition varied from 11.1 to 43.7% among sites and showed positive linear correlations with climatic factors as well as site productivity indices. After 2 years, about 60% of the litter mass was decomposed at the majority of sites in the middle and southern parts of the country. Mass losses ranged from 20 to 50% in northern Sweden. During later stages of decomposition, mass losses seemed to be highly dependent on the organic–chemical composition of the litter. For accumulated mass losses up to 65%, the annual mass loss of litter was described as a function of the holocellulose to lignocellulose ratio of the litter. For litter mass losses exceeding 65%, a significant linear relation between litter calcium content and mass loss rate was found. Significant linear relations were also obtained between annual lignin loss and litter calcium content.