RAINFALL WATER QUALITY UNDER DIFFERENT FOREST STANDS

Abstract

The rainfall-forest canopy interaction can impact on the chemical and physical rain-water features and is expected that different forests will have different effects on throughfall rain-water quality parameters. This study aimed (i) to compare chemical and physical rain-water quality variables observed in both gross precipitation and throughfall measured in two different forest stands (Atlantic semideciduous forest remnant - AFR, and a Eucalyptus urograndis plantation - EUP). Each stand was monitored with 8 internal rain-gauges and one external rain-gauge, encompassing the period from March 2015 to March 2016. The results pointed out a seasonal behavior of chemical and physical rain-water variables. Gross precipitation and throughfall presented different behaviors for pH, NH3^-, NH4⁺ and Ca hardness for AFR, and NH₃^-, NH₄⁺, Phosphate, Chloride, Ca hardness, Total Dissolved Solids and Conductivity for EUP. Besides, significant differences between the stands were found in terms of throughfall indicators for some of the rainfall events, remarkably NH₃ and NH₄ which were always higher at AFR. Additionally, we have noticed an effect of the monitoring points location as sources of spatial variability.