Litter fall in Mediterranean Pinus pinaster Ait. stands under different thinning regimes

Litter quantity and composition and its fall pattern throughout the year in Mediterranean pine afforestation of Pinus pinaster in Fuencaliente (Central Spain) were studied in relation to thinning treatments. The experiment lasted 10 years (1986-1995) and tested two low thinning regimes with a control one and with a stand that had never been thinned. Mean litter production for all years and treatments was 3284 kg ha−1 year−1 although it varies between 1520 kg ha−1 year−1 for the heavy thinning in 1994 and 5700 kg ha−1 year−1 for moderate thinning in 1989. Litter fall had two relative maximums throughout the year, the largest during the months of July, August and September, and the second one during January and February. The temperature of the previous month and moisture deficit resulted to be the most correlated climatic variables with monthly litter fall. Both time and treatments, and also their interaction, had a significant effect on litter fall, decreasing the quantity of litter fall with thinning intensity. Five years after thinning, this effect on the litter fall disappeared.