Probabilistic Modeling of Long-term Peatland Carbon Dynamics
Soil Sciences
Final Report Abstract
Northern peatlands are among the most dense and largest terrestrial soil carbon (C) stores. Production of litter from plants and slow decomposition due to oxygen limitation, low temperatures, nutrient limitation, and poor litter quality are key to peat accumulation over long time periods. Imbalances in these factors due to climate change may lead to large C losses to the atmosphere. Understanding how these processes interact quantitatively over long time periods is therefore important to understand the dynamics and potential risks of peatlands. Dynamic peatland models (DPM) are important tools to understand controls of processes on long time scales, to understand how they interact, and to estimate peatland states (e.g., mass fluxes, water table depths, vegetation community). Key outcomes of our project are: 1. Databases that provide data that support development and testing of DPM, in particular mid infrared spectra (MIRS) of peat and raw data on litterbag decomposition experiments. 2. Models that predict chemical and physical peat properties from MIRS. 3. Estimates of initial leaching losses and decomposition rates in available Sphagnum (one of the main peat forming genus in northern peatlands) litterbag experiments. Most previous litterbag studies and DPM do not directly consider the contribution of initial leaching losses to Sphagnum decomposition. Our analysis suggests that this biases estimates for decomposition rates and this bias amplifies over long time periods as simulated by DPM. We identify what aspects of litterbag experiments need to be improved for more accurate decomposition rate estimates. 4. Estimates for parameters of a decomposition module of a DPM from available Sphagnum litterbag data. This allows to describe how moisture conditions and oxygen availability control decomposition rates. Our analysis suggests that the decomposition rates decrease less strongly from oxic to anoxic conditions and that anaerobic decomposition rates are larger for many species than suggested by standard values of one widely used DPM, the Holocene Peatland Model. Depending on the environmental conditions, this can cause smaller or larger peat accumulation over long time periods. A possible explanation for these discrepancies is that the effect of water table fluctuations is not directly considered.
Publications
-
Improving models to predict holocellulose and Klason lignin contents for peat soil organic matter with mid-infrared spectra. SOIL, 8(2), 699-715.
Teickner, Henning & Knorr, Klaus-Holger
-
Comment on Hodgkins et al. (2018). California Digital Library (CDL).
Teickner, Henning & Knorr, Klaus-Holger
-
hklmirs: Reproducible research compendium for “Improving Models to Predict Holocellulose and Klason Lignin Contents for Peat Soil Organic Matter with Mid Infrared Spectra” and “Comment on Hodgkins et al. (2018)” (Version v.0.4.0)
Teickner, H. & Knorr, K.-H.
-
Compendium of R code and data for “A Synthesis of Sphagnum Litterbag Experiments: Initial Leaching Losses Bias Decomposition Rate Estimates” and “Underestimation of Anaerobic Decomposition Rates in Sphagnum Litterbag Experiments by the Holocene Peatland Model Depends on Initial Leaching Losses” (Version v0.0.0.9000)
Teickner, H., Pebesma, E. & Knorr, K.-H.
-
hpmdpredict: Predictions with model HPMe-LE-peat-l0 from Teickner et al. (2024) (Version 0.0.0.9000)
Teickner, H. & Knorr, K.-H.
-
Peatland Decomposition Database (1.0.0)
Teickner, H. & Knorr, K.-H.
-
A synthesis of Sphagnum litterbag experiments: initial leaching losses bias decomposition rate estimates. Biogeosciences, 22(2), 417-433.
Teickner, Henning; Pebesma, Edzer & Knorr, Klaus-Holger
