Graduate Studies

 

First Advisor

Paul R. Hanson

Degree Name

Doctor of Philosophy (Ph.D.)

Committee Members

David Wishart, Rebecca Buller, Sherilyn Fritz

Department

Geography

Date of this Version

2025

Document Type

Dissertation

Citation

A dissertation presented to the Graduate College of the University of Nebraska in partial fulfillment of requirements for the degree of Doctor of Philosophy

Major: Geography

Under the supervision of Professor Paul R. Hanson

Lincoln, Nebraska, August 2025

Comments

Copyright 2025, James Victor Benes. Used by permission

Abstract

This dissertation explores the spatiotemporal signatures of fire in North American grassland ecosystems. In three chapters, I explore different aspects of fire history in the northern Great Plains. Chapter 1 is an introduction. Chapter 2 focuses on the Euro-American Settlement Period (ca. 1850–1950 C.E.). Fire histories from six different lakes in the Nebraska Sandhills are compared with two periods of historic drought and the establishment of United States Post Offices. Five of the six records show increased levels of biomass burning during the initial phases of Euro-American Settlement. Chapter 3 is a long-term (ca. 15,000 years), high-resolution fire history and paleoecological reconstruction from Dewey Marsh in the north-central Nebraska Sandhills. Charcoal counts, grain size and organic content analysis reveals temporal trends in landscape disturbance around the marsh, primarily occurring when the adjoining dunes were mobilized during prolonged droughts. Charcoal was deposited on the surrounding dunes during wetter periods and was blown into the marsh during sand dune mobilization. Chapter 4 is a fire history reconstruction from Blyburg Lake, located on the floodplain of the Missouri River in northeastern Nebraska. The Blyburg Lake fire record is compared with trends in grain size analysis and reveals connections of fire occurrence with changes in silt and sand flux, both proxies for flooding on the Missouri River. Unstable winter conditions and increased flooding in the Upper Missouri basin are correlated with increased charcoal deposition in Blyburg Lake. Chapter 5 concludes the work of this dissertation. These chapters illustrate how charcoal accumulates in three different environmental settings and during different time periods over the last ~15,000 years. Knowing more about how fire fluctuates during changing environmental conditions will help inform a concise knowledge of the ecological operating range for future climatic changes in the northern Great Plains.

Advisor: Paul R. Hanson

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