Elevation-Dependent Phytolith Production in Norway Spruce: Toward a Quaternary “Phytolith Thermometer”

Norway spruce (Picea abies [L.] Karst.) is a paleoecologically relevant species in the Northern Hemisphere since the early Holocene. P. abies populations are sensitive to climate fluctuations; Asian treeline species are under nature protection. The thick wax and cuticle layers of spruce needles enhance their durability, making them frequent in glacial lake and peat bog cores. Their phytoliths are easily recognizable in sedimentary material and can be studied in subfossil tissues. The aim of this study is to assess the applicability of characteristic phytoliths from Norway spruce needles in paleoclimate research. We examined phytolith presence as a function of altitude in plant samples from three Carpathian Mountain ranges. Temperature data loggers were deployed at sampling sites to better characterize the thermal background of phytolith formation. Our results show a decreasing trend in phytolith presence with increasing elevation. The phytoliths formed by the transfusion tissue represent a sensitive type, indicating that spruce needle phytolith production responds to microclimatic variation. These findings are worth further investigation and validation. The study also provides a basis for refining the calculation method, contributing to the development of a potential “phytolith thermometer” for paleoclimatic reconstruction.