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

Abstract

Given the importance of carbon allocation for plant performance and fitness, it is expected that competition and abiotic stress influence respiratory costs associated with 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 2 years. We estimated growth R (Rg), maintenance R (Rm) and the growth respiration coefficient (GRC) using two gas exchange methods: (i) estimating Rg as the product of growth and GRC (then Rm as R minus Rg) and (ii) 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 from 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. The 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.

Differential response of oak and beech to late frost damage: an integrated analysis from organ to forest

“…The decrease in NSC concentrations in non-damaged beech trees observed after the end of the vegetative period (see rate of change in Fig. 5) could be related to the increased respiration rates in those trees showing more wood formation (Rodríguez-Calcerrada et al, 2019). Thus the higher resource acquisition capacity of non-damaged beeches would be partly compensated by increased respiration rates.…”

Survival time and mortality rate of regeneration in the deep shade of a primeval beech forest

“…In deep shade, slow growth is advantageous in the long term, due to low maintenance and respiration costs. Shade-tolerant species are able to decrease growth (and respiration) more efficiently than shade-intolerant ones (Rodríguez-Calcerrada et al 2019;Valladares and Niinemets 2008). Hence, the conventional belief that shade-tolerant species can survive in spite of suppressed growth should be revised because slow growth is actually a resource-saving strategy which enables survival.…”

TReSpire – a biophysical TRee Stem respiration model

“…The growth component is directly related to the growth yield ( Y G ), a parameter defined by the fraction of C added to structure per unit of substrate invested in growth metabolism. This parameter indicates how expensive is the synthesis of new biomass, and is therefore related to the species ecology (Lambers & Poorter, ; Rodríguez‐Calcerrada et al ., ). Here, Y G at the onset of the growing period (DOYs 155–160) was 0.818 ± 0.006 (95% CI), a coefficient at the upper end of reported values (0.7–0.85; Cannell & Thornley, ; Amthor, ).…”

“…It is worth noting, however, that literature comparison is not straightforward as different growth-related subprocesses taken into account (e.g. N reduction and uptake, and phloem transport) or analytical methods applied for calculation, substantially influence Y G estimates (Cannell & Thornley, 2000;Rodr ıguez-Calcerrada et al, 2019). Maintenance respiration relies on two parameters (R b_N and Q 10 ).…”