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

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.

Rainfall and throughfall chemistry in the Atlantic Forest: a comparison between urban and natural areas (São Paulo State, Brazil)

Two areas in the Atlantic Forest (São Paulo State, Brazil), with contrasting environments in respect of human occupation, were monitored from 1999 to 2001. One area named PEFI (23°38'08''-23°40'18'' S and 46°36'48''-46°38'00'' W) at an altitude of 798 m a.s.l., 526.4 ha in area and about 50 km from the sea, lies in a State Park within the largest metropolis of South America - São Paulo. The other area, named CUNHA (between 23°13'18'' and 23°16'10'' S and 45°02'53'' and 45°05'15'' W) about 1050 m a.s.l. with an area of 2854 ha and about 15 km from the sea, is also within a State Park in the Atlantic Forest, but is surrounded by rural areas and small villages. For each area, the rainfall and throughfall chemistry were examined and pH and Na+, K+, Mg2+, Ca2+, NH4+, Cl-, NO3- and SO42- as well as trace metals were determined. Compared with PEFI, CUNHA is characterised by low chemical fluxes and the largest differences are for the ions such as Ca2+, H+, NO3- and SO42- which are mainly anthropogenic in origin. Differences in throughfall chemical fluxes are linked to the nutritional status of the trees.