Soil nitrogen and mercury dynamics seven decades after a fire disturbance: A case study at Acadia National Park
Patel KF, Jakubowski MD, Fernandez IJ, Nelson SJ, Gawley W. 2019. Soil nitrogen and mercury dynamics seven decades after a fire disturbance: A case study at Acadia National Park. Water, Air, & Soil Pollution. 230(29)
From the abstract: "Forest soils (mainly soil organic carbon) play an important role in the retention of nitrogen and mercury, and loss of the forest floor during wildfires can stimulate N and Hg losses. In this paper, we investigate long-term impacts of forest fire on soil N and Hg concentrations at Acadia National Park (ANP) in Maine. Acadia National Park experienced a severe fire in 1947. Within the national park, Hadlock Brook watershed was left unburned, whereas most of Cadillac Brook watershed was intensely burned, with substantial loss of the forest floor. Post-fire regeneration in Cadillac was mostly as hardwood species, whereas vegetation in Hadlock remained predominantly softwood. We sampled soils in both watersheds in 2015, approximately 70 years after the fire. The soils were analyzed for total carbon (TC), total nitrogen (TN), total mercury (THg), and methylmercury (MeHg) content. Compared to Hadlock, Cadillac soils had ~50% lower TC, ~40% lower TN, and ~50% lower THg content, reflecting the loss of forest floor 70 years ago. Methylmercury concentrations in Cadillac were approximately 2 times the concentrations in Hadlock, indicating that conditions were more conducive to methylation, potentially due to differences in forest type. Long-term comparisons of stream DOC, NO3-, and THg concentrations between the two watersheds demonstrated that concentrations were significantly lower in Cadillac Brook, reflecting greater retention in Cadillac and a legacy of lower atmospheric deposition in the hardwood as compared to softwood watershed. This study provides insights on the multidecadal recovery from a stand-replacing disturbance and underscores the persistence of altered soil biogeochemistry."
- Type
- Journal Article
- Authors
- Patel, Kaizad; Jakubowski, Michael; Fernandez, Ivan; Nelson, Sarah; Gawley, William
- Units
- ACAD
- Keywords
- Atmospheric chemistry, Canopy, Carbon (C), Chemistry, Fire, Fire history, Forest, Forest communities, Habitats, Human impact, Mercury (Hg), Nitrates (NO3), Nitrogen (N), Plant communities, Regeneration, Rivers and streams, Soil, Soil chemistry, Vegetation, Vegetation change, Vegetation types, Watersheds