Research
Watershed Scale Environmental Change
Marsh Studies
Sites where sediment records are being studied
Researchers at the Paleoecology Lab at Lamont-Doherty examine sediments from Hudson Estuary marshes to study the region's past climate and vegetation. The group has also explored the timing of formation of the marshes on a south-to-north transect (Jamaica Bay to Iona Island, see Figure 1) in an attempt to understand their origin.
Studies of the Jamaica Bay marshes have focused on changes in sediment input related to human activities. Recent research in the Piermont and Iona marshes has specifically looked at sediment coinciding with the Medieval Warm Period (MWP) from about 800 to 1350 A.D. and the Little Ice Age which occurred between 1400 and 1800 A.D. Studies have also documented climatic shifts on the watershed scale that are indicated by changes in dominant forest species and large changes in the amount of charcoal deposited in the marshes created by wildfires during dry periods.
At the local scale, shifts in plant communities are visible as changes in macrofossils (seeds) that indicate changes in marsh salinity. The role of human impacts in the region since the 1600s are also important and show up in the vegetation record partly as a spread of invasive species such as the cattail Typha in the nineteenth century and Phragmites in the twentieth century. These ecological threshold indicators are important for us to understand what future shifts in climate hold for the region's vegetation.
Piermont Marsh in Piermont, N.Y.
Photo by Dorothy Peteet
Upland Studies
Paleo ecological research in the Hudson Valley involves using ponds, lakes, and marshes in the uplands of the Hudson region to investigate the timing of deglaciation after the last Ice Age. Basal sediments—those immediately above bedrock—from locations such as the marshes at the top of the Palisades cliffs, small ponds and lakes in Harriman Park and Black Rock Forest, and even as far north as Mohonk and the southern Adirondacks help reveal changes that occurred as the ice melted and plants moved from regions south of New York to this area.
These studies show evidence of abrupt climate shifts and fundamental changes in forest coverage over thousands of years. Understanding the timing of deglaciation is important for linking climate change in the Hudson Valley to changes that occurred in the North Atlantic Ocean, Europe and the globe.