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Date of Award


Document Type


Degree Name

Doctor of Philosophy in Forest Science (PhD)

College, School or Department Name

School of Forest Resources and Environmental Science

First Advisor

Joseph K. Bump


Mammals that directly affect both aquatic and terrestrial ecosystems include humans and some larger herbivores. This dissertation explores their ecological relationships through two broad themes: (1) reciprocal effects of larger mammalian herbivores and freshwater ecosystems, and (2) interventions that may improve human relationships with the ecosphere. Chapter 1 provides a brief background to these themes, and compares conventional approaches to assessing the environmental behavior of humans versus other animals. By analyzing concepts central to ecology or environmental psychology, insights emerge that can enrich the practice of the alternative discipline.

Chapter 2 investigates the role of aquatic and terrestrial plants and geomorphology in sustaining beaver in lakes over multiple decades. Findings suggest that vascular aquatic plants (macrophytes) and associated basin morphology can promote longer term and denser beaver occupancy. In contrast to terrestrial forage in the study system, some aquatic plant communities produce abundant edible biomass after decades of beaver and moose herbivory.

Chapter 3 examines conditions affecting the amount of aquatic-derived mercury consumed and transported by larger herbivores. Mercury exposure of generalist herbivores may be affected more by macrophyte community composition than by water mercury concentrations and other abiotic factors in Great Lakes National Parks. Estimated beaver mercury consumption exceeds reference doses for humans, indicating the potential for sub-lethal nervous impairment. In regions of high moose density, moose may be ecologically important vectors that transfer mercury from aquatic to surrounding terrestrial systems.

Chapter 4 investigates the effects of beaver and moose herbivory on freshwater abiotic conditions and plant communities. Results indicate that herbivores can alter light, plant biomass, and plant diversity. These effects appear contingent upon abiotic and plant community characteristics, and variable over multiple years.

Chapter 5 assesses whether and how locally-designed environmental education may affect students’ attitudes and behaviors toward stewardship of ecological and human communities. Students of environmental education gained awareness of the potential to harm nature more readily than environmental appreciation or stewardship intentions. However students gained environmental appreciation with increasing years in environmental education. Programs may have greater potential to strengthen students’ environmental orientations by fostering emotional connection to nature and recognition of human-nature interconnectedness.