Recent environmental changes inferred from the sediments of small lakes in Yellowstone's northern range
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Authors: D. R. Engstrom, C. Whitlock, S. C. Fritz, and H. E. Wright
Date: 1991
Journal: Journal of Paleolimnology
Volume: 5
Number: 2
Pages: 139-174
Summary of Methods: The landscape history of the last 150 years was reconstructed by the examination of the sedimentary record of eight small lakes in the northern range of Yellowstone National Park. The purpose was to determine if changes could be attributed to grazing and other activities of elk, bison, and other large ungulates. Sediment core samples were taken from the deepest part of each lake. Samples were examined for pollen content, diatoms, lead-210 dating and geochemistry.
Article Summary / Main Points: Several decades of the pre-Park era are recorded at most sites, and significant changes in certain profiles indicate that variations in environmental or sedimentological factors were effective under natural conditions. Profiles are slightly less complacent for the years after the Park was founded in 1872 than before, implying that Park management may have had some influence on lake sedimentation (e.g. road construction) In the early years of the Park an increase in conifer and Artemisia pollen and decrease in aspen pollen at several sites may record the beginning of fire suppression. The case for accelerated erosion in the northern range resulting from ungulate grazing is not supported by the stratigraphic studies, and pollen evidence for grazing on shrubs and trees is weak. Sediment composition and variability before and after the Park was established are similar. The conclusion is that the lake sediment records in the northern range do not show systematic direct or indirect effects of ungulate grazing during the history of the Park.
Vegetation Types: Grazed Forest Riparian and Wetlands
MLRA Ecoregions: 43B Central Rocky Mountains
Agrovoc Control Words: Limnology Rangelands Wildlife
Article Review Type: Refereed
Article Type: Documented Case History
Keywords: diatom stratigraphy, elk populations, erosion rates, lead-210 dating, paleoecology, paleolimnology, pollen analysis, range management, sediment geochemistry, ungulates, yellowstone national park
Annotation: The findings of this documented case study have limited implication on grazing management throughout the west, as it only examined the effect of wildlife grazing within Yellowstone National Park.
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