Characteristics of snowpack and snowmelt runoff chemistry in virgin Pinus koraiensis forest

We measured the pH, EC and concentrations of SO2-4, Cl-, NH+4, NO-3, total nitrogen (TN) and total phosphorus (TP) in snowpack and snowmelt runoffs in the virgin Pinus koraiensis forest in Liangshui Nature Reserve from March to May 2009. Combining with the thickness of snowpack, we discussed the characteristics and variations of snowpack and snowmelt runoff chemistry. The results were shown as the followings. 1) The chemical compositions varied among stands with different canopy closures, in which EC, Cl-, NO-3, SO2-4 and TN were highest in stands with a canopy closure of 0.5 or 0.6. It illustrated that the P. koraiensis forest with a canopy density of 0.5-0.6 was the most effective in retaining nutrients. The correlation analysis showed a significantly negative correlation between snowpack thickness and EC. The concentrations of SO2-4, Cl-, TN and NO- 3had extremely negative correlation with the thickness of snowpack as well. 2) During the snow melting period, the fluctuation ranges of the chemical constituents in the tributaries of the virgin Pinus koraiensis forest were smaller than those in the mainstream outlet except for pH. Both the tributaries and mainstream exhibited a phenomenon of “ionic pulse”, which appeared later in the tributaries with a lower peak. 3) The pH, EC and the concentrations of SO2-4 in the mainstream and tributaries were lower in the early snow melting period than in the snowpack, while the others showed an opposite tendency.