Synchronous responses of floodplain ecosystems to Holocene climate oscillations in Western Kamchatka (Russia): A case study from the middle reaches of the Icha River

Abstract

Multi-proxy palaeoecological reconstruction is a powerful tool for tracing past vegetation and ecosystem dynamics, yet such studies remain rare in Western Kamchatka. We investigated two Holocene sites from the Icha River valley using pollen, diatom, palaeozoological and plant macrofossil analyses, together with loss-onignition data, radiocarbon dating, and tephrochronology. Birch forests dominated the regional vegetation during the Middle and Late Holocene and were already widespread by 7800 cal yr BP. Local vegetation shifted from alder-dominated floodplain forest at 6000–5000 cal yr BP to a shallow oxbow lake bordered by tallherb meadow at 5000–4000 cal yr BP, then to a treeless fen at 4000–500 cal yr BP, and finally to a floodplain forest after 500 cal yr BP. These changes were controlled mainly by the floodplain regime, whereas climate acted indirectly through catchment hydrology. Ashfall may also have caused short-lived mire drying, although such effects were not always preserved in the palaeoecological record.