Decomposing biases in paleoenvironmental proxy data from pollen and micromammalian remains in caves: An actualistic approach

Abstract

Multiple forms of bias must be taken into account when interpreting paleoenvironmental proxy records in terrestrial Quaternary sequences. This fact complicates attempts to correlate records from different types of proxy data accumulated at the same site. We applied an actualistic approach to assess the correspondence between two major types of proxy data – pollen and micromammalian remains – in their representation of background vegetation within a cave site in Mount Carmel, Israel. Data on both pollen and micromammalian remains were extracted from a relatively large sample of 27 owl pellets accumulated inside the cave. These pellets were compared to other pollen sources from inside as well as outside the cave including owl nest sediment and samples from moss and lichen. These data were analyzed through multivariate correspondence analysis to examine associations among different pollen sources as well as between the pollen and micromammalian remains within the pellets. The pooled composition of the pellets revealed close association between pellets and moss samples from inside the cave. Moss and lichen samples from outside the cave, on the other hand, showed clear over-representation of Pinus pollen. In spite of some associations that we detected among specific pollen types and micromammalian taxa in the pellets when considering frequency data, there was good correspondence among the cave sources in representation of the Mediterranean Quercus maquis vegetation formation extending below the cave. We attribute these results in part to the relatively large sample of pellets and high taxonomic diversity. These findings are also explained by the interaction between two key factors including the orientation of the cave towards the nearby Quercus maquis and accumulation of both windblown pollen and pellets within the cave from this nearby source. We conclude that long-term pellet accumulations inside caves can contribute to inter-proxy correlation when dealing with pollen and micromammalian remains from pellet sources and provide important and reliable sources of paleoenvironmental data.