Reading environmental history from peat (Pymatuning Wetlands 2015, Day 12)

Today the Pymatuning wetlands spent the entire day in the lab. Our first day without any fieldwork since the course began.  However, we made up for it by doing a bit of time travel…

Examining plant microfossils from a peat core collected from Titus Bog.

Examining plant microfossils from a peat core collected from Titus Bog.

We examined the core we collected from Titus Bog yesterday.  We subsampled the sediment and peat, sieved the samples to isolate plant macrofossils (i.e., seeds, leaves, needles, etc.), and identified and tallied the microfossils to determine how the vegetation of the wetland has changed over the past 8000 or 9000 years.  The students determined that the site was occupied by a shallow lake prior to the establishment of the modern peatland, with submerged and floating leaved aquatic plants like Najas (water nymph), Nuphar (spatterdock), and Nymphaea (water lily) growing in the deeper portions of the littoral zone. Emergents like Cladium (sawgrass), Rhynchospora (beaked sedge), and other sedges likely occupied the lake margin along with small amounts of Sphagnum moss. The area abruptly became a floating peatland about 350 years ago, when Sphagnum became dominant.  The upland vegetation around the site contained Tsuga canadensis (hemlock), Pinus strobus (white pine), and Betula alleghaniensis (yellow birch) for much of the record. Most of the species in the paleoecological record have been observed at the wetlands we have visited during the past two weeks of the course; in fact, quite a few are the “must-know” list.

Summary macrofossil diagram from Titus Bog, PA.  Numbers per 10cm3 are plotted against depth in the core. Ages, in years before present, were estimated from Ireland and Booth (2011). The microfossil record was put together in one afternoon by seven students, with each student analyzing about 10 samples.

Summary macrofossil diagram from Titus Bog, PA. Numbers per 10cm3 are plotted against depth (cm) in the core. Ages, in years before present, were estimated from Ireland and Booth (2011). The microfossil record was put together in one afternoon by seven students, with each student analyzing about 10 samples.

Our age estimates for the record are tentative and come from a broader study of peatland development at the site by Ireland and Booth (2011).  We will discuss our paleoecological record in class tomorrow, along with the Ireland and Booth study, emphasizing the implications for understanding long-term wetland development and hydroseral succession.

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Posted on June 17, 2015, in Teaching, Wetland Ecology & Management (PLE) and tagged , , , , , , , , , . Bookmark the permalink. Leave a comment.

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