Difference between rainfall and throughfall chemistry for different forest stands in the Qinling Mountains, China

Abstract

This study compared the effects of four forest canopies on throughfall chemistry in the Qinling Mountains, China. Rainfall and throughfall samples were collected in stands of Quercus aliena (Qa) var. Acuteserrata, Pinus tabulaeformis (Pt), P. armandii (Pa), and mixed broad-leaved (Mb) trees from 2009 to 2011. The results indicated that the pH of the rainfall, which was mildly acidic, increased as it passed through the forest canopy. The pH increased more within the broad-leaved forest canopy than the coniferous forest. Concentrations of decreased as rainfall passed through the Qa canopy but increased after passing through the other species. The concentrations of and Zn, Cd and Pb decreased as rainfall passed through the four canopies. The coniferous forest canopy was more effective than the broad-leaved forest in reducing in rainwater. The decreases in Cd concentrations were similar among the four canopies. The Pb concentration decreased the most among the heavy metals, and the order of the decrease was Qa > Pt > Pa > Mb. The results may provide a basis for the selection of tree species for afforestation in water sources in the Qinling Mountains and similar areas. HIGHLIGHTS The broad-leaved forest canopies increased acidic rainfall pH more than the coniferous forest canopies.; The coniferous forest canopies were more effective in reducing in the rainwater.; The order of canopy decreasing Pb concentrations was Quercus aliena > Pinus tabulaeformis > P. armandii > mixed broad-leaved trees.; The decreases in Cd concentrations were similar among the four canopies.;

Keywords

• forest
• heavy metal
• qinling mountains
• rainfall
• throughfall
• water chemistry