Abstract

The objective of the study was to investigate the effects of different components of typical forests on water quality during the process of rainfall to runoff. Three typical forests, a Pinus massoniana × Gordonia acuminata Chang mixed forest (I₁), a Phyllostachys pubescens forest (I₂), a shrub forest (I₃)) and a bare land (a clear-cut), cited as a control plot (CK), at Jinyun Mountain, were selected as experimental sites. Four runoff plots were established on each of the four sites. Field monitoring for continuous measurements of water quality (rainfall, through fall, surface runoff and interflow) was carried out over 31 rain events during 2007 to 2010, using manual sampling methods. The results show that the rain water, with an average pH value of 5.43 in this area, was acidic. The water pH was mainly buffered at the conflux phase of surface runoff and forest stands had a better acid-buffer capacity than bare land. The concentration of NO₃^- played a leading role in the acidification of surface runoff and interflow in the forests. The amount of SO₄^2- was the dominant factor of acidification in throughfall. The main buffer elements in surface runoff were Mg²⁺ and Al³⁺; those of the interflow were Ca²⁺ and Al³⁺. An aluminum buffer system was present in I₁, I₃ and CK. During the four years of our study, the ions were mostly intercepted at the phase of the surface conflux and at soil level. Forests have better decontamination than bare land. I₁ and I₂ were better at interception with a large cut range of NO₃^-, SO₄^2-, K⁺, Na⁺, Mg²⁺ and Al³⁺.

Key words: forest, components, water quality, subtropics.