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Abstract Detail


Ecological Section

Pritchard, Seth [1], McCormack, M. Luke [2], Strand, Allan [1], Davis, Micheal [3], Breland, Sabrie [1], Oren, Ram [4].

Soil fungal dynamics in a loblolly pine forest exposed to elevated atmospheric carbon dioxide over a seven year period: interactions with soil N fertility.

Research on soil fungi is needed to predict how rising atmospheric CO2 will influence forest ecosystem processes and soil C sequestration potential. We examined the influence of FACE (Free Air CO2 Enrichment) and soil N availability on mycorrhizal and extraradical rhizomorph dynamics over a 7 year period in a loblolly pine forest, beginning in January of 2000 and running through January of 2007, using minirhizotrons. Standing crop of mycorrhizal root tips varied greatly spatially and through time. Summed across all years, CO2-enrichment increased mycorrhizal root tip production in deep soil (15-30 cm) but did not influence mycorrhizal production in shallow soil (0-15 cm). Production of mycorrhizae was reduced in N-fertilized plots compared to unfertilized controls. Production and mortality of soil rhizomorph length was significantly greater in CO2-enriched plots compared to controls over a 7 year period. Effects of atmospheric CO2 enrichment on longevity of mycorrhizal root tips and rhizomorphs varied with soil depth (mycorrhizae and rhizomorphs) and with diameter (rhizomorphs). For instance, survival of mycorrhizal tips was reduced in CO2-enriched plots in deep soil (15-30 cm depth) but was increased in shallower soil (0-15 cm). Longevity of mycorrhizal tips was greater in N-fertilized subplots, but only in deep soil (15-30 cm). A drought in 2002 coupled with loss of leaf area to an ice storm late in 2002 were followed by reductions in rhizomorph and mycorrhizal production, increases in mortality, and decreases in standing crop during 2003 and 2004. These effects tended to be more severe in CO2-enriched plots. Fungal production increased following the drought (2005-2007) and the effects of CO2-enrichment reappeared. Positive effects of atmospheric CO2 enrichment on mycorrhizal fungi, primarily observed in deeper soil, are probably contributing to the prolonged stimulation of NPP by CO2-enrichment at the Duke FACE study site.


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Related Links:
site for the Duke free air CO2-enrichment experiment
web site of first author


1 - College of Charleston, Department of Biology, 58 Coming Street, Room 214, Charleston, SC, 29401, USA
2 - Pennsylvania State University, Department of Horticulture, 103 Tyson Building, University Park, PA, 16802, USA
3 - The University of Southern Mississippi, Department of Biological Sciences, 118 College Drive # 5018, Hattiesburg, MS, 39406-0001, USA
4 - Duke University, Nicholas School of the Environment and Earth Sciences, Division of Environmental Science and Policy, Durham, NC, 27708-0328, USA

Keywords:
Elevated CO2
mycorrhizal fungi
rhizomorph
nitrogen limitation
nitrogen and carbon metabolism.

Presentation Type: Oral Paper:Papers for Sections
Session: 39
Location: 212/SUB
Date: Tuesday, July 29th, 2008
Time: 10:30 AM
Number: 39003
Abstract ID:402


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