title: Woody tissue maintenance respiration of four conifers in contrasting climates.
abstract: We estimate maintenance respiration for boles of four temperate conifers (ponderosa pine, western hemlock, red pine, and slash pine) from CO2efflux measurements in autumn, when construction respiration is low or negligible. Maintenance respiration of stems was linearly related to sapwood volume for all species; at 10°C, respiration per unit sapwood volume ranged from 4.8 to 8.3 μmol CO2m-3s-1. For all sites combined, respiration increased exponentially with temperature (Q10=1.7, r2=0.78). We estimate that maintenance respiration of aboveground woody tissues of these conifers consumes 52-162 g C m-2y-1, or 5-13% of net daytime carbon assimilation annually. The fraction of annual net daytime carbon fixation used for stem maintenance respiration increased linearly with the average annual temperature of the site.
authors.affiliation: Rocky Mountain Experiment Station, USDA Forest Service, 240 West Prospect Street, 80526-2098, Fort Collins, CO, USA.
authors.forename: Michael G
authors.initials: MG
authors.lastname: Ryan
authors.affiliation: Department of Forestry, University of Wisconsin, 53706, Madison, WI, USA.
authors.forename: Stith T
authors.initials: ST
authors.lastname: Gower
authors.affiliation: Rocky Mountain Experiment Station, USDA Forest Service, 240 West Prospect Street, 80526-2098, Fort Collins, CO, USA.
authors.forename: Robert M
authors.initials: RM
authors.lastname: Hubbard
authors.affiliation: Department of Forest Science, Oregon State University, 97331, Corvallis, OR, USA.
authors.forename: Richard H
authors.initials: RH
authors.lastname: Waring
authors.affiliation: Department of Forestry, University of Florida, 32611, Gainesville, FL, USA.
authors.forename: Henry L
authors.initials: HL
authors.lastname: Gholz
authors.affiliation: Department of Forestry, University of Florida, 32611, Gainesville, FL, USA.
authors.forename: Wendell P
authors.initials: WP
authors.lastname: Cropper
authors.affiliation: School of Forestry, University of Montana, 59812, Missoula, MT, USA.
authors.forename: Steven W
authors.initials: SW
authors.lastname: Running
keywords: Carbon budgets; Maintenance respiration; Temperature response; Woody-tissue respiration