Modern pollen distribution in a Connecticut saltmarsh: Implications for studies of sea-level change

Surface sediment samples were collected from a saltmarsh (Menunketesuck River Marsh) in Connecticut, USA, to establish (i) whether patterns exist in the representation of (a) upland; and (b) local (wetland) pollen grains in high intertidal environments; and (ii) to evaluate the significance of saltmarsh pollen assemblages in studies of regional sea-level change. At this site, upland pollen shows a remarkably even representation in the surface sediments of the high marsh zone; neither changes in surface vegetation nor small (<10 cm) changes in elevation have a significant impact on assemblage composition. Sediments from the upper marsh zone display only minor differences in upland pollen composition, which include a slight over-representation of pollen taxa from adjacent woodland. Channel-bank and ditch sediments display markedly different upland pollen assemblages, which include higher frequencies of well-dispersed coniferous pollen grains, (e.g., Pinus), heavy pollen grains, and grains derived from distal fluvial and marine sources. The representation of wetland pollen is strongly related to the distribution of local source vegetation. The results of the study support the assumptions which are made when pollen analysis is applied in sea-level studies.