Dynamics of the Water Quality in a Broad-leaf Evergreen Forest at Different Spatial Levels on Jinyun Mountain

Abstract

A typical forest stand on the subtropical Jinyun Mountain in China was selected to investigate water quality and interception characteristics for several important ions at different levels in the subtropical forest ecosystem. Based on field and laboratory experiments, the effect of precipitation, throughfall, litterfall, and soil percolation on water quality and ionic interception were investigated from September 2013 to August 2014. Results indicated that the rainfall on Jinyun Mountain was obviously acidic, with an average pH of 4.75. The soil and canopy can elevate the pH of rainfall, while the soil had a greater capability for adjusting pH than did the forest canopy. In addition, the concentrations of NH4+, SO42-, PO43-, Mg2+, Ca2+, and K+ in the litterfall increased with litterfall tissue disintegration, while the other ions decreased. Moreover, functional groups and colloids in the soil can bind or neutralize many ions, such as NO3-, SO42-, NH4+, PO43-, K+, and Mg2+. However, some ions were released from the soil by erosion from acid rain over a long time. Generally, the forest ecosystem is a sink for ions found in precipitation with diverse functions for different layers, and the forest canopy has the highest interception capacity for the ions found in precipitation.