A High-Resolution Palynological Analysis, Axel Heiberg Island, Canadian High Arctic

Abstract

A high-resolution sampling protocol was used to study the microflora from a two- meter thick siltstone unit located between two prominent coals representing Metasequoia- dominated swamp forests from the middle Eocene (ca. 45 million years old) Buchanan Lake Formation at Napartulik, Axel Heiberg Island, Nunavut, Canada. This detailed analysis fa- cilitated the reconstruction of the local vegetation history and provided possible explana- tions for the changes seen in the local shifting vegetation patterns. These changes are likely due to two phenomena: environmental disturbances, such as flooding and/or climate change and floral succession. Members of the Pinaceae dominated the local flora at times when the area was relatively dry, whereas Metasequoia Miki was predominant when local environ- mental conditions were more mesic. The pollen data provide evidence of successional pro- cesses and suggest that the local vegetation responded to climatic and environmental changes. More importantly, the pollen data indicate that the local floodplain vegetation was part of a larger, dynamic floral mosaic within a regional polar broad-leaved deciduous forest commu- nity and that periods of prolonged environmental stasis were generally limited to the swamp forest communities. Two major fern spikes were identified in the sequence and large-scale flooding was identified as being the likely disturbance factor responsible for landscape level reorganization.