Throughfall is an important component of water cycling in forest environments, largely because it provides a flux of nutrients to the forest floor that can be readily reabsorbed for use by vegetation and soil organisms. Compared to other nutrient inputs such as leaf litter, throughfall provides an immediate source of nutrients for uptake. Throughfall quantity and quality are dynamic fluxes, influenced by seasonality, species composition, and storm meteorological conditions. However, very little data are available regarding the spatial variance of throughfall inputs in southeastern forests. Therefore, the objectives of this study were to: (1) assess the temporal volumetric and chemical variation in throughfall, (2) measure soil nutrient composition and respiration, and (3) determine the relationship between throughfall and soil properties in a north‐central Mississippi temperate forest. Throughfall and open precipitation samples were collected bi-weekly across ten 30m x 30m plots from October 2014 to present to quantify temporal and spatial trends in throughfall hydrologic and biogeochemical fluxes. Soil respiration measurements were taken monthly and soil cores were collected seasonally from the O (litter layer), A (0-5cm), and B (5-10cm) horizons to quantify C and N concentrations.
Results/Conclusions
During winter when deciduous trees were bare, cumulative open precipitation was 80.5 cm with a mean throughfall of 80%. The summer leafed season had 9.7 cm of cumulative precipitation, with a mean throughfall of 58%. Data show that throughfall partitioning as a function of total precipitation increased exponentially, likely as a result of canopy saturation and overall intensity of precipitation events. Preliminary data indicate greater fluxes of dissolved organic carbon (DOC) in throughfall during the leafed season relative to the leafless season, likely a result of DOC leaching from canopy leaves. Within soil horizons, the litter layer had the largest percentage of carbon, due to the composition of leaf litter, pine needles and hardwood leaves, which serve as carbon stores. With increasing depth in the soil profile, carbon content decreased. Nitrogen content was relatively low and also decreased with depth in the soil profile. This trend indicates higher nutrient availability in the upper A horizon and organic soil layer. This study illustrates the seasonally driven variability of throughfall inputs in southeastern mixed-deciduous forests. Quantifying throughfall variability in these complex ecosystems is essential to our understanding of forest dynamics in changing climates.