Document Type

Dissertation - Open Access

Award Date


Degree Name

Doctor of Philosophy (PhD)

Department / School

Natural Resource Management

First Advisor

Lora Perkins

Second Advisor

A. Joshua Leffler


Understanding ecosystem processes in rangelands is of paramount importance for ensuring global food security, given their pivotal role in sustaining forage and livestock production. Central to this understanding are fundamental processes such as nutrient cycling, decomposition, and plant biomass dynamics. However, the use of anthropogenic chemicals in agricultural practices has the potential to exert significant influence on these critical ecosystem functions. A pivotal factor in this context is the plant diversity inherent to these rangeland ecosystems. Plant diversity not only provides essential ecosystem functions but also enhances them with the capacity to withstand and recover from perturbations. Ecosystems characterized by high levels of species diversity exhibit robust microbial dynamics and optimized nutrient cycling. These ecosystems are resilient in the face of disruptions such as anthropogenic chemical exposure. This dissertation delves into a comprehensive exploration of the impacts of two commonly employed pesticides: Ivermectin, a parasiticide, and Captan, a fungicide. The primary focus is on how these chemical agents influence ecosystem processes. I subsequently propose strategies to reinstate the integrity of ecosystem functions, bolster resistance, and fortify resilience. Through this work, invaluable insights are gleaned concerning the interplay between species diversity and chemical treatments, and their consequential ramifications on pivotal ecological processes. The findings indicate that anthropogenic chemicals commonly employed in agriculture exert a detrimental influence on non-target soil fauna, as well as nutrient cycling and plant biomass. Additionally, it was observed that plant diversity did not confer resistance or resilience, and there were noticeable lag effects that required time for the system to manifest and recover. This pioneering study stands as a notable contribution to the domain of applied ecology, enriching our cognizance of the intricate relationships governing ecosystem dynamics. Moreover, its findings hold significant implications for the advancement of sustainable land management practices, offering pragmatic guidance for the stewardship of rangeland ecosystems in a manner that harmonizes with both agricultural productivity and ecological equilibrium.

Library of Congress Subject Headings

Pesticides -- Environmental aspects.
Plant diversity.
Restoration ecology.
Resilience (Ecology)
Dung beetles -- Effect of chemicals on
Rangeland health.


South Dakota State University



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