TEMPERATURE SENSITIVITY OF NITROGEN MINERALIZATION IN PEAT FROM A SOUTHWESTERN MICHIGAN BOG

In this study, inorganic nitrogen (nitrate and ammonium) released from peat cores from Miner Lake bog was measured at two temperatures to analyze the impact of climate warming on the peatland nitrogen cycle. It was hypothesized that a higher nitrogen release in samples incubated at warmer temperatures. Furthermore, previous research indicates shallow peat decomposes faster than deeper peat. Therefore, it was hypothesized that faster nitrogen mineralization in shallow samples. Peat cores were collected from two locations from Miner Lake Bog in Allegan County, Michigan: a plot in the center of the bog and a sedge meadow site near the edge. Two samples for each depth (0-0.5 meter, 1.5-2 meters) were taken at both sites and homogenized. Microlysimeters, consisting of two-chambered filter towers, were acid washed and 20 g of acid washed sand was added to each upper chamber. 50 g of peat was added onto the sand and was left to equilibrate for four days. Microlysimeters were leached with 80 mL of 0.01M CaCl₂ solution and the concentration of nitrate and ammonium in the leachate were quantified using ion chromatography. Microlysimeters were incubated for two weeks before leaching procedures were repeated. A separate field-based cation-anion exchange analysis was performed through the installation of plant root simulators. In both the lab and field experiments, it was found that mineralization was higher in surface peat than in more degraded deep peat layers. Additionally, it was found that mineralization was higher at the warmer temperature, indicating that warming will increase the rate of nitrogen cycling in peatlands.