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The Response of Lakes to Disturbance and Climate Change: Calibrating Sedimentary Records to Test the Landscape Position Concept

Personnel

Principal investigators: Sara Hotchkiss, Randy Calcote, Jim Rusak, Patricia Sanford, Jasmine Saros, and Jarvis Erickson (grad student).

Project summary

A larger proportion of the water budgets of seepage lakes low in a hydrological gradient comes from groundwater, resulting in as much as an order of magnitude higher concentration of cations and silica in lakes at lower landscape positions. Landscape disturbances and climate change that alter the chemistry or abundance of major water sources should affect lakes in proportion to their relative water budgets. Previous work at the North Temperate Lakes Long Term Ecological Research site (NTL-LTER) in Wisconsin describes the importance of the landscape position concept in understanding the limnological differences between neighboring lakes, including the responses of lakes at different landscape positions to a four-year drought in the 1980s.

A major focus of this project is to develop and calibrate a broad range of paleoecological methods to test hypotheses derived from the landscape position concept over time scales that are not accessible to modern studies. Surface sediment samples with modern lake data from 62 lakes are being used to develop transfer functions which will be tested against 24 years of limnological data from the NTL-LTER database. After testing the paleoecological methods, a multi-proxy limnological reconstruction will be carried out using sediment records of the last 150 years from two of the LTER lakes. A future goal of this research is to test the prediction that the response of lakes in different landscape positions to severe droughts (multi-decadal to century scale) will be qualitatively and quantitatively different from the responses to the relatively mild drought of the late 1980s.

sediment core

freeze core