In this dataset, we provide the age-depth model of a lake sediment core covering the last 28 thousand years from the Siberian forest-tundra ecotone. The age model provides temporal information for a project that applies sedimentary ancient DNA metabarcoding using the plant-specific g and h primers of the trnL gene to track the compositional and diversity changes of terrestrial plants. Lake Ilirney is bounded by the Anadyr Mountains (up to 1790 m a.s.l.) to the north. According to the meteorological station at Ilirney, mean annual temperature is -13.5°C, and mean January and July temperatures are -33.4 and 12.1°C, respectively. Core “16-KP-01-L02 Long 3” was obtained from Lake Ilirney (67.34148, 168.30443) in summer 2016 as part of a joint Russian-German Expedition. The coring was accomplished using a UWITEC gravity corer equipped with a hammer action (Vyse et al. 2020; doi:10.1016/j.quascirev.2020.106607). The core has a total length of 235 cm. The age-depth model is based on Accelerator Mass Spectrometry (AMS) radiocarbon dating of seven bulk total organic carbon samples from this core (Andreev et al. 2020 in review) and correlation to a nearby 1040 cm sediment core with 25 dates (Vyse et al. 2020). 14C ages were calibrated using the IntCal13 calibration curve and modelled according to Andreev et al. (in review).