Large mammals and the zoogeochemistry of terrestrial nutrient cycles

Abraham, Andrew John (2021) Large mammals and the zoogeochemistry of terrestrial nutrient cycles. Doctoral thesis, Northern Arizona University.

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Abstract

Studies from across the world demonstrate that nutrient resource subsidies by animals critically shape ecosystem composition and function. In particular, large mammals have been found to act as the planet’s nutrient arteries, connecting and fertilising landscapes through which they pass. However, a comprehensive understanding of the cumulative impacts of lateral nutrient transport by diverse clades of mammal taxa remains lacking. This dissertation develops quantitative frameworks from which to better attribute and estimate the magnitude of nutrient redistribution by large mammals. First, I apply machine-learning techniques to improve the prediction of key animal traits (gut retention time) and nutrient biogeography (sodium). I then develop an agent-based model that incorporates individual-level decision making for quantifying the transport of nutrients across a nutrient discontinuity in the Amazon basin. Collectively, these studies improve our understanding of biotic nutrient dispersal and provide a framework that can be applied to diverse terrestrial ecosystems across the world. My final two chapters assess how wildlife managers can incorporate nutrient redistribution by large mammals into management plans, whereby holistic strategies promote the long-term fertility of landscapes. Over the last 50,000 years, numerous large mammal species have been extirpated from ecosystems across the world. Today, the global south shoulders much of the burden for preserving large mammal species. This dissertation provides a biogeochemical rationale for the growing movement of rewilding, which aims – in part – to rebalance the geographical responsibility for large animal conservation.

Item Type:	Thesis (Doctoral)
Publisher’s Statement:	© Copyright is held by the author. Digital access to this material is made possible by the Cline Library, Northern Arizona University. Further transmission, reproduction or presentation of protected items is prohibited except with permission of the author.
Keywords:	biogeochemistry; megaherbivore; phosphorus; savannah; tropical forest; large mammals; nutrient redistribution
Subjects:	Q Science > QL Zoology
NAU Depositing Author Academic Status:	Student
Department/Unit:	Graduate College > Theses and Dissertations College of the Environment, Forestry, and Natural Sciences > School of Earth Sciences and Environmental Sustainability
Date Deposited:	18 Feb 2022 16:18
Last Modified:	19 May 2023 08:30
URI:	https://openknowledge.nau.edu/id/eprint/5710

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