Holocene aquatic ecosystem change in the boreal vegetation zone of northern Finland

摘要: We studied multiple variables in a sediment core from Lake Kipojarvi, northern Finland, to investigate Holocene ecosystem changes relation catchment characteristics and known climate variations. focused on forested because previous paleolimnological studies conducted Fennoscandia mainly subarctic lakes within range of shifting treeline(s). Data aquatic macrophytes, diatoms, Cladocera, C:N ratio, organic matter (LOI) regional vegetation (pollen), revealed three-phase limnological development. The early Holocene, species-rich, mesotrophic lake was transformed into an oligotrophic, species-poor by the middle ca. 7,500 cal years BP, earlier than has generally been reported. transition involved considerable macrophytes. Changes Cladocera diatom communities appear have linked macrophyte development, which turn, probably regulated development hydrology, consequent decrease nutrient input catchment. During more humid late surface flow increased, but lake’s status remained oligotrophic. Possible reasons for low concentration include: 1) slower biogeochemical cycling due cooler climate, 2) new hydrologic outlet associated shorter water-retention times, 3) accelerated peatland that affected water patterns cycling.