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2014 Harvard Forest REU Student Symposium Abstracts

Maria Orbay-Cerrato Alvarez - Brown University

Coprophilous fungi spores as an indicator of grazing in New England during the past few centuries


By converting forests into agricultural lands, European settlers drastically changed the New England landscape. This disturbance left its mark in lake-sediment pollen records, with elevated abundances of grass, weeds, and agricultural plants during the settlement era. While pollen evidence for the shift from forests to fields has been widely documented, little attention has been paid to the paleoecological record of other agricultural practices, including grazing. In this study, we investigate the possibility of reconstructing the presence of grazers in post-settlement New England via the analysis of spores of coprophilous fungi. We hypothesized that dung-fungi spores would be present and most abundant during the height of European settlement, when thousands of sheep and cows grazed the pastures of New England. To explore this hypothesis, we collected a sediment core from Ware Pond, located in Marblehead, Massachusetts, a town that saw heavy grazing in the 19th century. We analyzed pollen using standard methods, with 300 grains counted at 400x magnification at each level. Our analyses revealed that pre-settlement forests featured oak, hickory, and beech. Pollen assemblages from the beginning of the settlement period featured grass, sorrel, and ragweed, with declining sorrel, increasing ragweed, and maximum values of grass and weedy taxa higher in the core. Spores of Sordaria, a coprophilous fungus, peaked at the same depth as the agricultural indicators. These findings suggest that the spores of dung fungi do reflect grazing, such that future studies should be able to use this approach to explore the patterns and impacts of grazing across New England.

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