High-altitude cushion peatlands contain important records for high-resolution palaeoenvironmental studies, due to their high carbon accumulation rates and sensitivity to climatic changes. In this study, we present the paleoenvironmental history for the last 2 500 years based on the study of APA01 core, located in the headwaters of the Cachi river basin in Ayacucho. Radiocarbon dating by an accelerator mass spectroscopy (AMS) and by an elemental PDZ Europa ANCA-GSL analyzer to estimate particulated organic carbon were determined. Our results reveal changes in the peatlands during the Late Holocene. The palaeo climate varied significantly during the last 2 500 years. During the Medieval Climatic Anomaly (ACM) from around 1040 DC (Before Christ - BC, in spanish paper) to 1300 DC, the drier climate caused a slowdown in peat accumulation due to a reduced water table inducing a reduced organic matter production with a negative peak of carbon concentration. At the end of the Small Ice Age (PEH), between 1600 DC and 1890 DC, carbon accumulation showed high variability. Subsequently, the peat environment is mainly characterized by a considerable increase of carbon accumulation rates due to high sedimentation rates that is possibly related to the retreat of glaciers in the Central Andes. The recent drastic increase in the sedimentation rate and the reduction of carbon concentrations are a warning of a possible future decline of these ecosystems.