Phosphorus transformations and leaching potential in rewetting drained peatlands: Exploring the influence of land use and temperature.

Understanding phosphorus (P) transformation dynamics during peatland rewetting is crucial for developing effective management strategies, supporting ecological restoration initiatives and mitigating potential environmental risks. This incubation study explored the temporal variations in P transformation in peatlands under different land uses (cut grass, grazing, unmanaged) along with the potential risk of leaching by simulating rewetting conditions for four months at varying temperatures (10 and 20 °C). Overall, only a small fraction of the initial total phosphorus (P) was leached during rewetting. Among land uses, soils under grazing showed the highest release (0.34%), followed by cut grass (0.19%) and unmanaged land (0.13%). A higher risk of leaching at the beginning of the rewetting was observed to be associated with a high transformation rate of P from organic form to inorganic form but mitigated by resorption with ongoing rewetting. Soil organic carbon, initial contents of P, iron, and aluminium as well as temperature were found to be the main factors controlling P transformation and leaching during the rewetting process. Increasing incubation temperature from 10 °C to 20 °C raised P release by 33-41%. Moreover, a projected 1.5 °C increase in temperature due to climate change is estimated to increase the rate of phosphorus (P) transformation and release by approximately 24%, based on temperature sensitivity analysis. More research is needed to comprehensively explore complex interactions involving seasonal variations, microbial activity, and geological processes. This is also necessary for a holistic understanding of how these ecosystems may respond to ongoing climate changes.