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Date of Award

2016

Document Type

Campus Access Master's Thesis

Degree Name

Master of Science in Applied Ecology (MS)

Administrative Home Department

School of Forest Resources and Environmental Science

Advisor 1

Rodney A. Chimner

Committee Member 1

Randall K. Kolka

Committee Member 2

Molly A. Cavaleri

Committee Member 3

Nancy Langston

Abstract

Forested peatlands are important natural ecosystems in the global carbon cycle due to their large carbon pools in both standing biomass and thick organic soils. Northern white cedar (cedar; Thuja occidentalis L.) peatlands are a common and ecologically important forested peatland type in the Great Lakes Region of North America. Despite the great potential of cedar peatlands to store carbon, very few studies have characterized the fluxes or cycling of carbon in these ecosystems. Furthermore, the last 100-150 years have seen a dramatic shift in the age distribution of cedar stands, due primarily to harvesting for forest products and overbrowsing by large deer herds in the region. The aims of this thesis are to 1) evaluate the feasibility of enrichment planting as a restoration option in cedar peatlands, and 2) characterize the production of dissolved organic carbon (DOC) and the soil emissions of carbon dioxide (CO2) and methane (CH4) in a cedar peatland.

Five restoration sites across northern Minnesota were used in investigating the conditions that fostered optimum height growth and survival of planted cedar seedlings. Planted cedar were found to grow and survive best when planted on hummocks. Additionally, a combination of protection from browse and high light maximized height growth of planted cedar. One site in the Upper Peninsula of Michigan was used for measurements of soil emissions of CO2 and CH4 and concentrations and characterizations of DOC. Soil CO2 emissions were correlated with water table level but CH4 emissions were not, possibly due to sufficiently high water tables throughout the measurement season. The quantity and quality of DOC changed with depth, suggesting that DOC lower in the peat profile was microbially sourced. When compared to other northern peatlands, soil CO2 emissions were relatively low, and soil CH4 emissions were approximately average. Dissolved organic carbon was also within the range of values from other northern peatlands, but was less aromatic and had a lower molecular weight. The results from this study suggest that the carbon dynamics of cedar peatlands are important. Additionally, enrichment planting appears to be a feasible strategy in restoration of degraded peatlands for at least two years after planting.

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