QUANTITATIVE ANALYSIS OF GEOLOGIC AND CLIMATIC CONTROLS ON THE REGIONAL SCALE VARIABILITY OF THE PLANT-SOIL SYSTEM IN THE CRITICAL ZONE

Geological features and climate shape the Critical Zone, but the wide variation regionally causes a discrepancy between belowground properties and the aboveground ecosystem. These discrepancies make it difficult to predict trends of soil-plant interactions across a regional scale. We aimed to capture the spatial variability in the plant-soil system by sampling across a spatial gradient, across the greater New England area ranging from Vermont and New Hampshire to Connecticut and Rhode Island. We implemented a grided sampling system of forty-eight sampling sites longitudinally and latitudinally spaced at 30km ± 2km. At each site we collected forest floor samples with corresponding soil samples (0-10cm, 10-20cm, 20-30cm, 30-40cm, 40-50cm) and four upper canopy hardwood tree leaf samples. Macro and micronutrients were measured in plants and soils as well as soil physiochemical properties (pH and % soil organic matter) of all soils. Average foliar macronutrient (Ca, K, Mg, P) concentrations were 7,242, 805, 2,296, 1,839 (mg/kg) respectively. Foliar macronutrient concentrations increased from southern plateaus and basins of glacial outwash and fluvial deposits to shallow montane lodgment glacial till. Similar patterns were investigated for bioavailable and strong acid extractable macro and micronutrient concentration. Further spatial analysis will illuminate geologic and climatic controls of soil spatial variability.