Evaluating the Palaeoecological Potential of Pollen Recovered from Ice in Caves: A Case Study from Scărişoara Ice Cave, Romania

Scărişoara Ice Cave (NW Romania) contains the world\u27s largest underground perennial ice deposit. In this paper we present the results from pollen, micro- and macro-charcoal, and plant macrofossil investigations of a vertical ice exposure spanning the past ca. 1000 years in the Little Reservation from this cave. These results are then compared with three peat sequences close to the study area in order to evaluate the potential of using biotic remains preserved in the ice block for past vegetation, environment and climatic reconstructions. Pollen data from Scărişoara Ice Cave suggest that each impurity-poor layer is likely to include a smaller number of years, compared to organic-rich layers in which repeated, multi-annual melting events may have concentrated a higher amount of organic matter. However, layers with abundant presence of organic matter and also containing plant macro-remains, micro- and macro-charcoal particles appear to indicate a rapid wash-in of surface material into the cave. Evidence from the pollen record suggests the prevalence of close forest dominated by Fagus sylvatica between ca. AD 1200 and 1500 and by Picea abies between ca. AD 1000 and 1500 and from AD 1550 onwards. Contrary to the pollen records from the surface, the pollen assemblages from Scărişoara Ice Cave are characterized by low frequencies and diversity of pollen of herbaceous plants (non-arboreal pollen, NAP) and coprophilous spores. However, there are fluctuating frequencies in these taxa, which appear to track changes in climate conditions (higher during the Medieval Warm Period and lower during the Little Ice Age), which suggest that land-use changes were likely modulated by the climate. High amounts of micro- and macro-charcoal particles between AD 1600 and 1850, when climate conditions were cool and wet, suggests that the charcoal was washed into the cave during times of extreme rainfall events, rather than associated with increased burning regime. A comparison with pollen records from the surface shows analogous forest development and fluctuations in the NAP, therefore supporting the hypothesis that the cave ice can be a valuable paleoecological archive