Throughfall and Stemflow as Hot Phenomena of Biogeochemical Fluxes in Temperate Swamps

English Abstract:

The production of throughfall (TF) and stemflow (SF) is precipitation-driven and has been shown to acquire various plant leachates as these hydrologic fluxes pass through a tree canopy. Enrichment of TF and SF with dissolved organic carbon (DOC), nitrogen (N) and various other compounds increase the ability of these hydrological fluxes to bring chemicals, beneficial or potentially harmful, to the soils present under the vegetative canopy. TF and SF have the potential to induce hot phenomena upon reaching the soil below due to the biogeochemical pulses provided by them. This is especially true for SF, which has been proven to contain higher DOC and nutrient concentrations than precipitation (P) and TF and has preferential access to the soil matrix via the root system of the tree. This study presents the investigation of the biogeochemical fluxes of TF and SF during P events in two swamps of southern Ontario. These biogeochemical fluxes and resulting hot phenomena impact nutrient cycling, species composition and water quality in wetlands, with this study providing a unique look at these fluxes during the growing season in two temperate mixed-deciduous swamps. With the aid of this research, wetland conservation and management authorities can obtain important information regarding the fluxes of DOC and N species into temperate swamps, as well as the dissolved organic matter (DOM) character of TF and SF. The objectives for this study were to determine the quantity of DOC and N present in TF and SF and how they differ between different stands and different tree species. Additionally, an analysis of DOM character in TF and SF was performed to determine the amount of bioavailable organic material (relative molecular mass), aromaticity and fluorescence properties (fluorescence index, EEM’s, PARAFAC) of each.