Eradication of the Invader: Interactions Between Arrhenatherum Elatius Management Practices and Soil Nitrogen Cycling

Leung, Michelle

Undergraduate Honors Thesis

Eradication of the Invader: Interactions Between Arrhenatherum Elatius Management Practices and Soil Nitrogen Cycling 公开 Deposited

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Citeable URL: https://scholar.colorado.edu/concern/undergraduate_honors_theses/8s45qb17t

Abstract

Due to climate change and other global change drivers, there is an increased risk of invasion in native plant communities as non-native species tend to thrive under increased levels of CO₂ and increased atmospheric nutrient deposition. Invasion of non-native species can cause shifts in ecosystem function due to changes in plant community composition that cause modifications in nutrient cycling, organic matter decomposition, and soil ecology. Currently, the Western United States (U.S.) consists of numerous non-native species in tallgrass prairie ecosystems. As a result, land managers are using several different management technique to eradicate and limit their spread including prescribed burning, mechanical removal, herbicides, and livestock grazing. Boulder Open Space and Mountain Parks (OSMP) in the Colorado Front Range of the Rocky Mountains have been increasing efforts to eliminate the spread of Arrhenatherum elatius (A. elatius), which has persisted in ecosystems of the Front Range for the past 20 years. This honors thesis project investigates how cattle grazing and prescribed fire— common management strategies to limit the growth and spread of A. elatius—interacts with soil nitrogen (N) cycling at Shanahan Ridge, Boulder, Colorado. The data presented include net N cycling processes— mineralization and nitrification – and aboveground vegetation biomass in four different treatment sites: past graze, recent graze, graze + burn, and no management. Graze + burn was associated with lower rates of N cycling processes compared to recent graze and past graze. However, differences among treatments were not statistically significant for soil N cycling measurements (p > 0.05). There were statistical differences in the amount of thatch for graze + burn, past graze, and recent graze (p < 0.05). Overall, these data suggest that the interactions between grazing and soil N cycling rates are perhaps due to complicating factors that differ across the sites. This project provides foundational knowledge regarding how management techniques could be influencing nutrient cycling and A. elatius growth. It will help to inform Boulder OSMP’s management techniques as they relate to control of A. elatius and changes to ecosystem function.

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