COMPARING NUTRIENT VS TOXIC ELEMENT BIOGEOCHEMISTRY IN MID-ATLANTIC AND NEW ENGLAND FORESTS – SIMILARITIES ABOVEGROUND BUT DIFFERENCES BELOWGROUND

Essential nutrients such as Ca, Mg, and P are needed in temperate forests for forest products and protecting water quality and resources. However, weathering of minerals and human pollution has enriched toxic element such as As, Cd, and Pb in forest ecosystems. The rate of biogeochemical cycling in the tree-soil system can be difficult to predict at the regional scale several key variables co-vary across regions, especially mean annual temperature, forest genus-species composition, and soil parent materials. Variations in the composition of the forest and the soil parent material control the cycling of nutrients and toxic elements via uptake rates, aboveground storage, litterfall and throughfall recycling, belowground storage, and eventually river export. Here, we evaluated the biogeochemistry of nutrients and toxic elements at six sites in two contrasting forest ecosystems, maple-beech-birch glacial till-dominated New England forests in Frigid soil temperature regimes and the hickory-oak-tuliptree colluvial-residuum dominated Mid-Atlantic forests in the mesic soil temperature regime. Aboveground nutrient and toxic pools were generally comparable between the two regions. Belowground New England sites had significantly larger Mg soil pools but smaller As and Cd soil pools than Mid-Atlantic. Aboveground mean residence times was comparable for nutrients but significantly shorter for As and Cd for New England sites than Mid-Atlantic sites. Belowground mean residence times for Ca, As, Cd, and Pb were significantly longer for Mid-Atlantic sites than New England sites but Mg was shorter for Mid-Atlantic than New England sites. Our results show elemental cycling varied strongly belowground between regions and between sites.