Influence of Climate Change and Settlement on Lithology of Peat Deposits in the Zielonka Forest (Central-Western Poland)

Peat deposits preserve records of palaeoecosystems, their evolution and their relation with human activity. Lithological analysis of mineral material in peat allows us to identify the processes and conditions that accompany environmental evolution. In this paper, the results of a lithological investigation of a mire located in the subglacial valley of the Trojanka River in the Zielonka Forest (central-western Poland) are presented, aiming to reconstruct processes associated with climate shift and human activity in the vicinity of the mire. For this purpose, four peat cores from the foot of a conical hillfort were collected and subjected to laboratory analyses. AMS ¹⁴C dating was performed on nine samples from core GL I, indicating that the profile covers the period since 850 ± 30 BP. LOI laser diffraction and grain-size analyses were conducted. The results indicate that the peat was enriched with coarser mineral fractions, which may reflect periods of increased fluvial activity of the Trojanka River. The earliest phase of intensified fluvial activity was recorded in the 11^th century. The transition from the MWP to the LIA in the first half of the 16^th century is reflected in mineral alluvial layers deposited during significant rises in water level. The study shows that the presence of the conical hillfort did not have a significant influence on the enrichment of peat with slope-derived material. Peat formed during the LIA and in modern times is characterised by a high accumulation rate and a higher mineral matter content compared to peat deposits formed during the MWP.