title: Soil respiration, root biomass, and root turnover following long-term exposure of northern forests to elevated atmospheric CO2 and tropospheric O3.
abstract: The Rhinelander free-air CO(2) enrichment (FACE) experiment is designed to understand ecosystem response to elevated atmospheric carbon dioxide (+CO(2)) and elevated tropospheric ozone (+O(3)). The objectives of this study were: to understand how soil respiration responded to the experimental treatments; to determine whether fine-root biomass was correlated to rates of soil respiration; and to measure rates of fine-root turnover in aspen (Populus tremuloides) forests and determine whether root turnover might be driving patterns in soil respiration. Soil respiration was measured, root biomass was determined, and estimates of root production, mortality and biomass turnover were made. Soil respiration was greatest in the +CO(2) and +CO(2) +O(3) treatments across all three plant communities. Soil respiration was correlated with increases in fine-root biomass. In the aspen community, annual fine-root production and mortality (g m(-2)) were positively affected by +O(3). After 10 yr of exposure, +CO(2) +O(3)-induced increases in belowground carbon allocation suggest that the positive effects of elevated CO(2) on belowground net primary productivity (NPP) may not be offset by negative effects of O(3). For the aspen community, fine-root biomass is actually stimulated by +O(3), and especially +CO(2) +O(3).
authors.affiliation: Department of Natural Resources & Environmental Science, University of Nevada, Reno, NV 89512, USA.
authors.forename: Kurt S
authors.initials: KS
authors.lastname: Pregitzer
authors.affiliation: Ecosystem Science Center, School of Forest Resources & Environmental Science, Michigan Technological University, Houghton, MI 49931, USA.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Burton
authors.affiliation: Department of Forestry and Environmental Resources, North Carolina State University, Raleigh, NC 27695, USA.
authors.forename: John S
authors.initials: JS
authors.lastname: King
authors.affiliation: School of Natural Resources & Environment and Department of Ecology & Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109, USA.
authors.forename: Donald R
authors.initials: DR
authors.lastname: Zak
mesh_terms: D001272:Atmosphere / Q000737:chemistry; D018533:Biomass; D002245:Carbon Dioxide / Q000378:metabolism*; D017753:Ecosystem; D017752:Greenhouse Effect; D010126:Ozone / Q000378:metabolism*; D018517:Plant Roots / Q000254:growth & development* / Q000378:metabolism; D032107:Populus / Q000254:growth & development* / Q000378:metabolism; D012987:Soil; D014197:Trees / Q000254:growth & development / Q000378:metabolism
chemical_list: D012987:Soil; D002245:Carbon Dioxide; D010126:Ozone