Legacy Effects of Forest Clearcutting on Ecosystem Function and Biogeochemical Cycling in a New England Forest

Terrestrial soils comprise the largest reservoirs of carbon (C) in the biosphere holding some 2500 Gt C, which is 4x the amount found in plant biomass and 3x the C content of the atmospheric pool. Approximately 1500 Gt of soil C is in an organic form, thus making it available to mineralization by heterotrophic organisms [10]. Changes to the drivers of mineralization such as climate change and aeration due to anthropogenic land use, such as logging, have the potential to strongly affect global carbon and associated nutrient cycles, plant production, and atmospheric composition. With the aim of better understanding the potential long-term implications of forest logging on ecosystem function and soil biogeochemistry we conducted a range of measurements in the field and laboratory to elucidate patterns along a 20-year old clearcut and adjacent 100+ year old forest stand located in two experimental large gaps in Yale Myers Forest, Eastford, CT. A decrease in organic matter and reduced soil biotic activity in the experimental large gaps when compared to the 100+ year old forest due to the potential changes in edaphic conditions and biodiversity associated with disturbance is expected. Leaf litter samples collected from the study sites Kozy Road and Tree Heaven underwent elemental analysis to measure the change in litter carbon and nitrogen throughout the experiment. Soil samples were collected at each litterbag collection throughout the sampling period to provide a surface and subsurface snapshot of the biology at that time in each transect. Soil samples were analyzed for four ecoenzymes that play a pivotal role in carbon and nutrient cycling in soil, B-glucosidase (BG), Acid Phosphatase (AP), Nacetylglucosaminidase (NAG), and Xylosidase (XYLO). Results found an overall increase in average C and N percentages in both Kozy Road and Tree Heaven over the course of this study, which may indicate mineralization and immobilization is occurring and resulting in an accumulation of soil organic matter. The highest EEA values were found for BG and AP. This result may be explained by the fact that BG hydrolyzes cellulose. Acid Phosphatase works upon organic phosphorus and converts it into its inorganic form, an essential nutrient for all life. Labile organic material and organic phosphorus were the primary targets of the ecoenzymes analyzed in this study. In the coming months, we plan to continue to measure and collect data from samples collected beyond the nine month cutoff for this study extending data collection to 12 and 18 months in order to conduct more intensive hypothesis testing and multivariate statistics