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Tree Physiol. 2019 Jun 18. pii: tpz069. doi: 10.1093/treephys/tpz069. [Epub ahead of print]

Respiratory costs of producing and maintaining stem biomass in eight co-occurring tree species.

Author information

1
Forest Genetics and Ecophysiology Research Group, School of Forestry Engineering, Universidad Politécnica de Madrid, Ciudad Universitaria s/n, 28040, Madrid, Spain.
2
Laboratory of Plant Ecology, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000 Ghent, Belgium.
3
Department of Ecology, Brandenburg University of Technology, Cottbus, Germany.

Abstract

Given the importance of carbon allocation for plant performance and fitness, it is expected that competition and abiotic stress influence respiratory costs associated to stem wood biomass production and maintenance. In this study, stem respiration (R) was measured together with stem diameter increment in adult trees of eight co-occurring species in a sub-Mediterranean forest stand for two years. We estimated growth R (Rg), maintenance R (Rm) and the growth respiration coefficient (GRC) using two gas exchange methods: 1) estimating Rg as the product of growth and GRC (then Rm as R minus Rg) and 2) estimating Rm from temperature dependent kinetics of basal Rm at the dormant season (then Rg as R minus Rm). In both cases, stem basal-area growth rates governed intra-annual variation in R, Rg and Rm. Maximum annual Rm occurred slightly before or after maximum Rg. The mean contribution of Rm to R during the growing season ranged from 56 to 88% across species using method 1 and 23 to 66% using method 2. An analysis accounting for the phylogenetic distance among species indicated that more shade-tolerant, faster growing species exhibited higher Rm and Rg than less shade-tolerant, slower growing ones, suggesting a balance between carbon supply and demand mediated by growth. However, GRC was not related to species growth rate, wood density, or drought- and shade-tolerance across the surveyed species, nor across 27 tree species for which GRC was compiled. GRC estimates based on wood chemical analysis were lower (0.19) than those based on gas exchange methods (0.35). These results give partial support to the hypothesis that wood production and maintenance costs are related to species ecology, and highlight the divergence of respiratory parameters widely used in plant models according to the methodological approach applied to derive them.

KEYWORDS:

carbon balance; carbon flux; forest dynamics; forest succession; mixed forest; respiration modeling; sapwood; stem CO2 efflux; xylem production

PMID:
31211374
DOI:
10.1093/treephys/tpz069

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