Modern palynological assemblages in fjord surface sediments: indicators of Greening Svalbard

The Arctic is experiencing rapid climatic warming. The inflow of warm Atlantic Water through the Fram Strait is an additional forcing to the stability of the Arctic cryospheric system, with the Svalbard archipelago being especially sensitive to its primary influence. While recent studies show the “greening” of this region through remote sensing and field observations, this study investigates modern palynological assemblages from fjord surface sediments at 34 different locations in Spitsbergen and Nordaustlandet to explore where this phenomenon is prevalent at an ecosystem scale. Long-distance transported pollen such as Pinus and Betula are consistently identified across fjords, while various and local pollen compositions are observed more in Isfjorden where intensive human activity and substantial retreat of tidewater glaciers have been reported. In addition to herbaceous pollen taxa, shrub pollen including Salix and Dryas is present on the western side of the archipelago more often. During pollen identification, abundant testate amoebae were also detected at most locations. We propose the following explanation on the observed palynological assemblages. Overall, pollen records from the surface fjord sediments reflect terrestrial environmental conditions effectively and spatially. The exposure of newly deglaciated surfaces where soils develop, subsequent ecological succession on these soils facilitates Arctic shrubification. Soil development can be inferred from testate amoebae, and Arctic greening can be detected through local pollen spectra. In our future analysis, the onset of these modern palynological assemblages can be identified through the investigation of fjord long core sediments.