LITTER FALL AND LITTER DECOMPOSITION IN PINUS-SYLVESTRIS FORESTS OF THE EASTERN PYRENEES

Litter fall and litter decomposition were studied in four mature stand s of Pinus sylvestris (Scots pine) in the eastern Pyrenees. The stands were located in environments differing in bedrock type and exposition and were studied for two years. Mass-loss during the first year of de composition was compared with other European P. sylvestris forests and regressed with environmental variables (temperature and rainfall) and latitude. The results suggested that the mean amount of needle fall ( 1760 kg.ha(-1).yr(-1)) was within the range reported for northern Euro pean stands. There were more differences in the amount of litter fall between the four stands than between the two years studied. However, t he needle fall pattern over the year showed significant differences be tween years in three of the four stands. Litter decomposition was simi lar in all the stands and only the one in drier conditions showed a lo wer decomposition rate. On the European scale the decomposition rate w as positively related to mean annual temperature and annual rainfall. However, regression analysis suggests that there are other factors, no t taken into account in this study, that are important for predicting the decomposition rate.