Award Date


Degree Type


Degree Name

Master of Science (MS)


Biological Science

First Committee Member

Stanley D. Smith

Number of Pages



The purpose of this research was to determine the effect of elevated atmospheric carbon dioxide conditions on forage quality for the desert tortoise (Gopherus agassizii), using a common diet component, Bromus rubens. Nitrogen balance was monitored for tortoises fed pelleted diets reflecting the nitrogen levels of Bromus plants grown under elevated and ambient CO2 conditions, with varying potassium levels (3.5% and 1.4% DWB). Nitrogen content in the diet approached a positive correlation with total diet intake (p = 0.11), and was positively correlated with nitrogen loss at alpha = 0.10 (p = 0.08) and yet remained positively correlated with nitrogen retention (p = 0.07) in high potassium diets. When consuming lower potassium diets, no significant responses were seen with respect to nitrogen content of diets, although nitrogen retention approached significance (p = 0.11). These results, suggest that under elevated CO2 -conditions, if dietary nitrogen levels decrease, nitrogen retention abilities are likely to be compromised, especially when plants simultaneously contain large amounts of potassium.


Bromus; Carbon Consequences; Desert; Dioxide; Effects; Elevated; Nutritional; Rubens; Tortoise

Controlled Subject

Physiology; Botany; Environmental sciences; Range management

File Format


File Size

1259.52 KB

Degree Grantor

University of Nevada, Las Vegas




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