The Holocene vegetation history of an isolated, high-arctic plant diversity hot spot

Abstract

Through high throughput sequencing of ancient, environmental DNA collected from lake sediment cores (sedaDNA), this study revealed postglacial vegetation change during the last ~12.000 years in a high-Arctic plant diversity hot spot in Svalbard. Geochemical proxy data for environmental variation in the catchment area obtained from high resolution X-radiographic scans were combined with the sedaDNA record to detect local Holocene climate variations. The findings were in accordance with main climatic shifts on Svalbard identified by previous studies and indicated an early warm and species-rich postglacial period followed by fluctuating cool and warming events throughout the Holocene record. Thermophilic species with their current distribution outside the catchment area of the studied lake had reoccurring presence throughout the Holocene sedaDNA record, suggesting postglacial periods when thermophilic arctic species had broader distribution ranges than today. This supports the hypothesis of isolated relict populations in Ringhorndalen, the place in Svalbard with the highest registered diversity of vascular plants and several remarkable and isolated plant populations located far north of their normal distribution range.