DECOMPOSITION RATES OF SCOTS PINE NEEDLE LITTER RELATED TO SITE PROPERTIES, LITTER QUALITY, AND CLIMATE

Decomposition of Scots pine (Pinus sylvestris L.) needle litter was st udied at 14 sites along a climatic transect through Sweden. The forest s 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 Ist year of decompositio n varied from 11.1 to 43.7% among sites and showed positive linear cor relations with climatic factors as well as site productivity indices. After 2 years, about 60% of the litter mass was decomposed at the majo rity of sites in the middle and southern parts of the country. Mass lo sses ranged from 20 to 50% in northern Sweden. During later stages of decomposition, mass losses seemed to be highly dependent on the organi c-chemical composition of the litter. For accumulated mass losses up t o 65%, the annual mass loss of litter was described as a function of t he holocellulose to lignocellulose ratio of the litter. For litter mas s losses exceeding 65%, a significant linear relation between litter c alcium content and mass loss rate was found. Significant linear relati ons were also obtained between annual lignin loss and litter calcium c ontent.