Effects of canopy interception on epikarst water chemistry and its response to precipitation in Southwest China

The effects of vegetation on epikarst water are unclear due to the lack of understanding of the effects of canopy interception on epikarst water properties. In this study, throughfall (T), stemflow (S), borehole (B) and epikarst (E) spring water (PTSBE profile) from two different vegetation canopies, forest and shrub, from July to October 2015 in Southwest China, were sampled to investigate the effects of canopy interception on epikarst water chemistry and its response to precipitation. Significant difference in pH, EC, and DO concentrations exists among precipitation, throughfall, stemflow and epikarst water. Stemflow is an acidic input and throughfall is a less acidic input to the epikarst zone. The mean δ18O value of precipitation is −7.45‰, and the mean δ18O values of throughfall in forest and shrub are −7.11 and −7.37‰, respectively. The results indicate that precipitation becomes acid and nutrient enrichment after canopy interception. The canopy also alters hydrologic cycle processes and enhances the precipitation solute input to the epikarst zone. Our study suggests that precise interpretation of the mechanisms of carbonate rock dissolution and deposition requires the use of throughfall and stemflow.