Evaluation of the Holocene Peat Model with Data from Boreal and Subarctic Peatlands of the James Bay Lowlands, Quebec, Canada

The Holocene Peat Model (HPM) is a dynamic model simulating the transient evolution of a peatland since its early stages. HPM takes into account the feedbacks between vegetation, peat properties, water table depth, and climate. The aim of this study is to evaluate the HPM by means of empirical data. Three distinct sampling sites were chosen within a large region including boreal and subarctic peatlands in the James Bay lowlands, northern Quebec, Canada. One fen and one bog were selected in the subarctic region and another bog in the boreal region. These sites have different geographical, climatological and ecological features (e.g. pH, nutrient availability, hydrology and species composition). Five cores from those three sites were dated using 210Pb and 14C. Loss on ignition and plant macrofossils analysis were performed for each core. First, we compare the simulation results of the HPM for the study sites with the information earned in the field and laboratory. In order to capture the causes for discrepancies between simulated and observed data, we then constrained the model in two ways: 1) The water balance of HPM was forced with water table fluctuations reconstructions, obtained from a transfer function of Testate amoebae. 2) The bulk density of HPM was forced with the bulk density data obtained from the cores. In both cases, the results highlight the effectiveness of the water balance and the bulk density routines of the HPM and also draw attention to other potential causes of inaccuracy in the model