Variations and determinants of tissue carbon concentration of 32 sympatric temperate tree species

Plant carbon (C) concentration is a fundamental trait for estimating C storage and nutrient utilization. However, the mechanisms of C concentration variations among different tree tissues and across species remains poorly understood. In this study, we explored the variations and determinants of C concentration of nine tissues from 216 individuals of 32 tree species, with particular attention on the effect of wood porosity (i.e., non-porous wood, diffuse-porous wood, and ring-porous wood). The inter-tissue pattern of C concentration diverged across the three porosity types; metabolically active tissues (foliage and fine roots, except for the foliage of ring-porous species) generally had higher C levels compared with inactive wood. The poor inter-correlations between tissue C concentrations indicated a necessity of measuring tissue- and specific-C concentrations. Carbon concentration for almost all tissues generally decreased from non-porous, to diffuse-porous and to ring-porous. Tissue C was often positively correlated with tissue (foliage and wood) density and tree size, while negatively correlated with growth rate, depending on wood porosity. Our results highlight the mediating effect of type of wood porosity on the variation in tissue C among temperate species. The variations among tissues were more important than that among species. These findings provided insights on tissue C concentration variability of temperate forest species.