NITROGEN AND PHOSPHORUS LEACHING FROM THE FOREST FLOOR OF A MATURE PINUS-RADIATA STAND

In a mature Pinus radiata plantation we studied the amounts and forms of nitrogen and phosphorus leached from the forest floor paying special attention to seasonal changes. Forest floor leachates were collected using zero-tension lysimeters placed underneath the Oa horizon. A large amount of the N and P leached throughout the year leached during short periods of time (61% of the P and 51% of the N in two months). The amount of litter and its quality (C, N and P concentration and the C:N, C:P and N:P ratios) were not related to spatial variability in litter leachates. The seasonal pattern of inorganic P concentration and leaching suggested that peaks could be attributed to increases in throughfall that were not completely retained by organic layers. Organic forms accounted for a high proportion of the N and P leached, especially for the former.