Solutes in overland flow following fire in eucalyptus and pine forests, northern Portugal

Small bounded plots were used to investigate dissolved nutrient losses in o verland flow in eucalyptus and pine forests in northern Portugal following understorey fires. Losses of NO3--N, PO43-, Ca2+, Mg2+ and K+ were measured over 19 months during the first 2-3 years after fire. Solute losses in ove rland flow increased after fire in eucalyptus and pine terrain due to the m ineralization of litter and vegetation and increased overland flow. The dat a suggest that (i) elevated losses persist for at least 2 and 3 years at th e pine and eucalyptus sites respectively and (ii) soluble losses of PO43- a nd K+ in a post-fire cycle may exceed those adsorbed to eroded material, Lo sses of PO43-, although relatively small, are potentially the most detrimen tal to soil fertility and forest productivity because of the limited opport unity for P replenishment and correspondingly high P losses adsorbed to ero ded sediment. Copyright (C) 2000 John Wiley & Sons, Ltd.