17 Lakes and Environmental Change

Sunday, 20 March 2011
1:30 PM - 5:30 PM
Conference B

HOLOCENE STRATIGRAPHY AND CLIMATE HISTORY OF SLUICE POND, MA

Paper number: 17-4
Program: Theme Sessions
Time: 2:15 PM – 2:30 PM

Authors

Abstract

Recent work, including pollen and lake level studies in New England, demonstrates the dynamic nature of climate variability during the Holocene Epoch. Here, we investigate the seismic- and litho-stratigraphy of Sluice Pond, MA and reconstruct local climatic conditions. We collected sub-bottom profile data and two dated sediment cores (deep basin and margin locations) between 2007-10. Sediment proxy data include pollen and thecamoebian abundances, organic matter deposition (LOI), density, magnetic susceptibility, δ13C, δ15N, and C/N ratios.

The lower portion of the basin core reveals a time of cold/dry climate from ca. 11,500 - 8,000 cal BP. Evidence includes Picea and Pinus pollen zones, geophysical reflectors that pinch out at depths <18m, generally low organic matter preservation, and a lack of sedimentation in the margin core. An increase in regional temperature/moisture is apparent in sediments younger than 8,000 cal BP. Pollen data indicate the establishment of a mixed forest ecosystem. Organic matter deposition reaches a maximum in the basin core, and the initiation of gyttja deposition in the margin sediment core at 7,800 cal BP confirms a lake level increase.

A warm/dry climate is suggested from ca. 5,000 – 3,500 cal BP. This interval has been identified as the Tsuga minimum zone. During this time interval, the marginal core contains an abundance of macrophyte remains, suggesting a decrease in lake level to account for the macrophyte’s affinity for the photic zone. The warm/dry period had a delayed trigger on productivity as organic matter deposition first decreased and then increased along with an increase in thecamoebian abundance at ca. 4,000 cal BP. Younger sediments suggest unstressed, organic-rich conditions until the most recent sediments. The upper-most sediments record anthropogenic disturbance with increases in non-arboreal and Betula pollen, the stress-tolerant thecamoebian Difflugia protaeiformis, and a large increase in δ15N. Additionally, increases in magnetic susceptibility, trace metals, and dry bulk density, along with a relative decrease in organic matter, argue for land-use change. The climate variability interpreted from the sediments of Sluice Pond is consistent with other studies from New England, suggesting regional climatic forcings.