Using species attributes to characterize late‐glacial and early‐Holocene environments at Kråkenes, western Norway

• Published in: Journal of vegetation science 2019-11, Vol.30 (6), p.1228-1238
• Main Authors: Felde, Vivian Astrup, Birks, Hilary Helen, Giesecke, Thomas
• Format: Article
• Language: English
• Subjects: assemblage weighted means; biome reconstruction; chironomids; early Holocene; Ecological conditions; Ecosystems; Ellenberg indicator values; Encroachment; environmental change; Geographical distribution; Glacial periods; Glaciers; Holocene; late glacial; macrofossils; Mountains; Nitrogen; Organic soils; Permafrost; Plant fossils; Polar environments; Soil moisture; Soil temperature; Soils; Species; species attributes; temperature reconstruction; Tundra; Variation
• ISSN: 1100-9233; 1654-1103
• DOI: 10.1111/jvs.12804

Aim We aim to use species attributes such as distributions and indicator values to reconstruct past biomes, environment, and temperatures from detailed plant‐macrofossil data covering the late glacial to the early Holocene (ca. 14–9 ka). Location Kråkenes, western Norway. Methods We applied attributes for present‐day geographical distribution, optimal July and January temperatures, and Ellenberg indicator values for plants in the macrofossil data‐set. We used assemblage weighted means (AWM) to reconstruct past biomes, changes in light (L), nitrogen (N), moisture (F), and soil reaction (R), and temperatures. We compared the temperature reconstructions with previous chironomid‐inferred temperatures. Results After the start of the Holocene around 11.5 ka, the Arctic‐montane biome, which was stable during the late‐glacial period, shifted successively into the Boreo‐arctic montane, Wide‐boreal, Boreo‐montane, Boreo‐temperate, and Wide‐temperate biomes by ca. 9.0 ka. Circumpolar and Eurasian floristic elements characteristic of the late‐glacial decreased and the Eurosiberian element became prominent. Light demand (L), soil moisture (F), nitrogen (N), and soil reaction (R) show different, but complementary responses. Light‐demanding plants decreased with time. Soil moisture was relatively stable until it increased during organic soil development during the early Holocene. Soil nitrogen increased during the early Holocene. Soil reaction (pH) decreased during the Allerød, but increased during the Younger Dryas. It decreased markedly after the start of the Holocene, reaching low but stable levels in the early Holocene. Mean July and January temperatures show similar patterns to the chironomid‐inferred mean July temperature trends at Kråkenes, but chironomids show larger fluctuations and interesting differences in timing. Conclusion Assigning attributes to macrofossil species is a useful new approach in palaeoecology. It can demonstrate changes in biomes, ecological conditions, and temperatures. The late‐glacial to early‐Holocene transition may form an analogue for changes observed in the modern arctic and in mountains, with melting glaciers, permafrost thaw, and shrub encroachment into tundra. We demonstrated the value of applying species’ attributes to the palaeoecological reconstruction of past environments and climates. We used modern‐day distributions of plant species, indicator values, and optimal January and July temperatures to reconstruct late‐glacial and ea