Understanding the carbon cycle of major ecosystems is important in predicting feedback responses of the terrestrial biosphere to climate change. Bromus tectorum dominated ecosystems currently cover 7% of the Great Basin and represents a major land cover type for the region. This study looked at the carbon cycle of a near monoculture field of B. tectorum in southeastern Idaho, USA. A major portion of the study was dedicated to measurement validation because of the disagreement among techniques used to measure net ecosystem exchange (NEE) of CO2 between the atmosphere and terrestrial ecosystems . NEE, net photosynthesis, and canopy and soil respiration were quantified for the B. tectorum stand using multiple methods. This allowed for comparisons among measurement techniques and permitted the calculation of a best estimate of NEE. The study found that the eddy covariance technique underestimated NEE at night for the B. tectorum stand and the magnitude of underestimation increased with increasing leaf area index of the plant canopy. Annual NEE estimated by eddy covariance for the year 2005 was over four times lower than the best estimate of -80 g C m-2 yr-1 determined by a combination of methods. Implications are that many studies currently underestimate NEE and productive systems underestimate NEE more than less productive systems.
| Identifer | oai:union.ndltd.org:UTAHS/oai:digitalcommons.usu.edu:etd-7675 |
| Date | 01 May 2007 |
| Creators | Myklebust, May Christin |
| Publisher | DigitalCommons@USU |
| Source Sets | Utah State University |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | All Graduate Theses and Dissertations |
| Rights | Copyright for this work is held by the author. Transmission or reproduction of materials protected by copyright beyond that allowed by fair use requires the written permission of the copyright owners. Works not in the public domain cannot be commercially exploited without permission of the copyright owner. Responsibility for any use rests exclusively with the user. For more information contact digitalcommons@usu.edu. |
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