Effects of Elevated Atmospheric CO₂ on Scrub-Oak Root Carbon Pools and Soil Microbial Processes

<p>The levels of atmospheric CO₂ are rising and this affects the growth of plants and the ecosystems in which they reside. Plants take up additional C from the atmosphere and have potential to sequester C in the soil. I investigated the sequestration of C belowground and the microbial processes that control C retention in the soil. This study was conducted in a Florida scrub-oak ecosystem, where CO₂ levels have been elevated to twice ambient since 1996 in open top chambers. There were eight replicates of ambient CO₂ chambers and eight replicates of twice-ambient CO₂levels. The chambers were blocked according to the vegetation present at the beginning of the study and the site was burned prior to construction of the chambers. Soil cores were taken to investigate the effects of elevated CO₂ on soil biomass pools, microbial response and nutrient limitations. Elevated CO₂ did not affect total biomass of roots as of May 2002. There was less biomass of the smallest roots (2 in the top 10 cm. The C and N contents of root and organic matter pools reflected the trends in biomass. N concentration was lower for 2. An oxygen biosensor system was used to examine microbial function in the scrub-oak soils. Microbial response was affected by CO₂ treatments. The soil microbial communities had greater N limitation in elevated CO₂ than ambient CO₂, while the litter community was unaffected. The rhizosphere community had greater P limitation in elevated CO₂ than ambient CO₂ . Substrates for the microbes derived from roots and litter grown in elevated CO₂seemed to have more energy available to microbes, but this was dependent upon N conditions. Overall, there was greater nutrient limitation of microbial activity in elevated CO₂ than ambient CO_2, but the scrub-oak ecosystem was nutrient limited regardless of CO₂ conditions preventing full use of the potential C available for energy.</p>

Name thesis:degree_name

Doctor of Philosophy (PhD)

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Biological Sciences

Year dc:date.available

2006

Author dc:creator

• Brown, Alisha Lea Pagel

Contributors dc:contributor

• Frank P. Day
• J. Patrick Megonigal
• Joseph Rule

• Atmospheric carbon dioxide
• Carbon pools
• Roots
• Scrub oak
• Soil microbes
• Biogeochemistry
• Ecology and Evolutionary Biology
• Soil Science

Statement dc:rights

• <p>In Copyright. URI: <a href="http://rightsstatements.org/vocab/InC/1.0/">http://rightsstatements.org/vocab/InC/1.0/</a> This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).</p>

Identifier

9781109834970

OAI identifier oai:identifier

oai:digitalcommons.odu.edu:biology_etds-1097