The role of disturbance in Great Plains grassland community dynamics

UNCG Author/Contributor (non-UNCG co-authors, if there are any, appear on document)
Kathryn J. Bloodworth (Creator)
The University of North Carolina at Greensboro (UNCG )
Web Site:
Koerner Koerner

Abstract: Disturbances impose a state of disequilibrium on ecosystems, often leading to the maintenance of ecosystem type and prevention of state shifts. Grasslands serve as a model system for assessing disturbance regime shifts, as they are disturbance-dependent ecosystems. Fire, climate, and herbivory are key disturbances in maintaining grasslands, but these regimes are shifting due to anthropogenic activity. Fire intensity is increasing while frequency is decreasing, and precipitation is becoming more variable, with longer and more intense droughts projected. Moreover, grasslands are being exploited for agricultural use, often resulting in a shift of primary herbivores from native species to cattle grazers while terrestrial arthropods—globally important herbivores—are decreasing in abundance. Thus, we must work to understand how shifts in these regimes will affect future biodiversity and ecosystem function in grasslands. To explore ecosystem changes as disturbance regimes shift, I focused on the Great Plains of North America where I performed a meta-analysis exploring the effects of fire frequency across multiple abiotic and biotic ecological factors (Chapter II) and used experimental and observational approaches to determine drought effects on plant communities (Chapter III) and assess the effects of cattle grazing and precipitation regime shifts on arthropod communities (Chapter IV). In Chapter II, I found that there is no “one-size-fits-all” fire management strategy to benefit all ecological factors in tallgrass prairie, however fire in unison with grazing creates a heterogeneous landscape, which benefits many ecological factors. In Chapter III, I provide evidence that plant communities in northern mixed-grass prairie are resistant to drought, likely due to shifts in plant species traits; however, this outcome is variable based on site and environmental factors. Finally, in Chapter IV, I demonstrated that precipitation mediates the effects of cattle grazing on arthropod communities, with diversity of arthropods increasing with cattle grazing intensity only in drought years. Overall, my work advances scientific knowledge on how anthropogenic and climate change driven shifts in disturbance regimes impact community dynamics and ecosystem function in Great Plains grasslands. As grasslands make up 40% of the earth’s ice-free surface and contribute to the livelihoods of more than 800 million people worldwide through agricultural goods and services, providing evidenced-based information to land managers about how novel disturbance regimes impact grassland biodiversity and function will be critical to promote long-term sustainability of the ecosystem and will increase global food security.

Additional Information

Language: English
Date: 2024
Arthropods, Cattle grazing, Drought, Fire, Grasslands, Plant community
Grassland ecology $z Great Plains
Ecological disturbances $z Great Plains
Grasslands $z Great Plains $x Management

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