title: Aboveground autotrophic respiration in a Spanish black pine forest: Comparison of scaling methods to improve component partitioning.
abstract: Total wood CO2efflux (Rw) varies vertically within individual trees, and leaves experience large variations in foliar respiration (Rf) rates over their life spans and during daily periods. Therefore, accurate sampling approaches are required to improve aboveground autotrophic respiration (RAa) estimations in stand-scale carbon cycling studies. We scaled-up Rw(comprising stem and branch CO2efflux; ES and EB, respectively) and Rffrom biometric and flux-chamber measurements taken between 2011 and 2013 in a Spanish black pine (Pinus nigra Arn. ssp. salzmannii) forest at an unburnt (UB) site and a low burn-severity (LS) site. We measured seasonal ES at breast height (1.30m) on 9 trees at each site, which was also vertically examined on 5 of those trees. We also measured seasonal Rfin current- and previous-year needles on 3 trees at each site, and quantified Rfvariations in darkness and light. Finally, we compared complex and simple scale-up methods which did or did not account for the vertical variation in Rwand the effects of leaf ageing and light inhibition on Rf, respectively. The simple methods underestimated the annual stand-level stem, branch, and total wood respiration ≈35%, 55%, and 41%, respectively, and overestimated annual stand-level whole-canopy foliage respiration ≈43% at both sites. Both methods provided similar annual stand-level RAaestimates, although the complex methods improved estimations of the relative contribution of RAacomponents. Thus, based on the complex methods the mean annual RAaat the stand-level was 4.53±0.25 and 4.45±0.12MgCha-1year-1at the UB and LS sites, respectively. Our data also confirmed that the low-severity fire did not alter the RAarates. Collectively, this study reveals that complex approaches, applicable in other forest ecosystems, enhance the accuracy of partitioning RAasources by reducing the error in scaling-up in chamber-based measurements.
authors.affiliation: Department of Science and Agroforestry Technology and Genetics, Higher Technical School of Agricultural and Forestry Engineering, University of Castilla-La Mancha, Campus Universitario s/n, CP 02071 Albacete, Spain; Environmental Department, Renewable Energy Research Institute, University of Castilla-La Mancha, Campus Universitario s/n, CP 02071 Albacete, Spain. Electronic address: Eduardo.Martinez@uclm.es.
authors.forename: E
authors.initials: E
authors.lastname: Martínez-García
authors.affiliation: Department of Science and Agroforestry Technology and Genetics, Higher Technical School of Agricultural and Forestry Engineering, University of Castilla-La Mancha, Campus Universitario s/n, CP 02071 Albacete, Spain; Environmental Department, Renewable Energy Research Institute, University of Castilla-La Mancha, Campus Universitario s/n, CP 02071 Albacete, Spain.
authors.forename: T
authors.initials: T
authors.lastname: Dadi
authors.affiliation: Department of Applied Physics, School of Industrial Engineering, University of Castilla-La Mancha, Campus Universitario s/n, CP 02071 Albacete, Spain; Environmental Department, Renewable Energy Research Institute, University of Castilla-La Mancha, Campus Universitario s/n, CP 02071 Albacete, Spain.
authors.forename: E
authors.initials: E
authors.lastname: Rubio
authors.affiliation: Department of Science and Agroforestry Technology and Genetics, Higher Technical School of Agricultural and Forestry Engineering, University of Castilla-La Mancha, Campus Universitario s/n, CP 02071 Albacete, Spain; Environmental Department, Renewable Energy Research Institute, University of Castilla-La Mancha, Campus Universitario s/n, CP 02071 Albacete, Spain.
authors.forename: F A
authors.initials: FA
authors.lastname: García-Morote
authors.affiliation: Department of Science and Agroforestry Technology and Genetics, Higher Technical School of Agricultural and Forestry Engineering, University of Castilla-La Mancha, Campus Universitario s/n, CP 02071 Albacete, Spain; Environmental Department, Renewable Energy Research Institute, University of Castilla-La Mancha, Campus Universitario s/n, CP 02071 Albacete, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Andrés-Abellán
authors.affiliation: Department of Science and Agroforestry Technology and Genetics, Higher Technical School of Agricultural and Forestry Engineering, University of Castilla-La Mancha, Campus Universitario s/n, CP 02071 Albacete, Spain; Environmental Department, Renewable Energy Research Institute, University of Castilla-La Mancha, Campus Universitario s/n, CP 02071 Albacete, Spain.
authors.forename: F R
authors.initials: FR
authors.lastname: López-Serrano
keywords: Foliar respiration; Kok method; Low burn-severity fire; Mediterranean mountain ecosystem; Stem CO(2) efflux