The influence of bigleaf maple on chemical properties of throughfall, stemflow, and forest floor in coniferous forest in the Pacific Northwest

Abstract

It is predicted that bigleaf maple ( Acer macrophyllum Pursh) will almost double in frequency in British Columbia by 2085 due to climate change. We address whether its frequency increase could influence chemical properties of throughfall, stemflow, and forest floor due to species-specific effects. Eight plots with a single bigleaf maple tree in the centre of conifers were paired with eight Douglas-fir ( Pseudotsuga menziesii (Mirb.) Franco) plots without bigleaf maple. Compared with conifer plots, bigleaf maple throughfall and stemflow had higher pH and K concentration. The under-canopy and near-trunk forest floor associated with bigleaf maple showed higher pH, total exchangeable bases, cation-exchange capacity, and concentrations of exchangeable Ca and Mg. In addition, the near-trunk forest floor had higher base saturation and concentrations and contents of NO3-N and contents of total N and S. Throughfall and stemflow beneath bigleaf maple appear to contribute to higher pH and N availability in the forest floor. The results suggest that there is a soil microsite around bigleaf maple stems that is influenced by stemflow. These enriched microsites proximal to bigleaf maple trunks would allow bigleaf maple to have legacy effects on soil fertility and promote conifer productivity later in succession following bigleaf maple mortality.