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We measured a diverse range of foliar characteristics in shrub and tree species in temperate rainforest communities along a soil chronosequence (six sites from 8 to 120000 years) and used multilevel model analysis to attribute the proportion of variance for each trait into genetic (G, here meaning species-level), environmental (E) and residual error components. We hypothesised that differences in leaf traits would be driven primarily by changes in soil nutrient availability during ecosystem progression and retrogression. Several leaf structural, chemical and gas-exchange traits were more strongly driven by G than E effects. For leaf mass per unit area (MA), foliar [N], net CO2 assimilation and dark respiration rates and foliar carbohydrate concentration, the G component accounted for 60-87% of the total variance, with the variability associated with plot, the E effect, much less important. Other traits, such as foliar [P] and N:P, displayed strong E and residual effects. Analyses revealed significant reductions in the slopes of G-only bivariate relationships when compared with raw relationships, indicating that a large proportion of trait-trait relationships is species based, and not a response to environment per se. This should be accounted for when assessing the mechanistic basis for using such relationships in order to make predictions of responses of plants to short-term environmental change.

Summary: Leaf dark respiration (R dark ) is an important yet poorly quantified component of the global carbon cycle. Given this, we analyzed a new global database of R dark and associated leaf traits. Data for 899 species were compiled from 100 sites (from the Arctic to the tropics). Several woody and nonwoody plant functional types (PFTs) were represented. Mixed-effects models were used to disentangle sources of variation in R dark . Area-based R dark at the prevailing average daily growth temperature (T) of each site increased only twofold from the Arctic to the tropics, despite a 20°C increase in growing T (8-28°C). By contrast, R dark at a standard T (25°C, R dark 25 ) was threefold higher in the Arctic than in the tropics, and twofold higher at arid than at mesic sites. Species and PFTs at cold sites exhibited higher R dark 25 at a given photosynthetic capacity (V cmax 25 ) or leaf nitrogen concentration ([N]) than species at warmer sites. R dark 25 values at any given V cmax 25 or [N] were higher in herbs than in woody plants. The results highlight variation in R dark among species and across global gradients in T and aridity. In addition to their ecological significance, the results provide a framework for improving representation of R dark in terrestrial biosphere models (TBMs) and associated land-surface components of Earth system models (ESMs). © 2015 New Phytologist Trust.

Background and aims: Our study quantified variations leaf respiration in darkness (R D) and light (R L), and associated traits along the Franz Josef Glacier soil development chronosequence in New Zealand. Methods: At six sites along the chronosequence (soil age: 6, 60, 150, 500, 12,000 and 120,000 years old), we measured rates of leaf R D, R L (using Kok method), light-saturated CO2 assimilation rates (A), leaf mass per unit area (M A), and concentrations of leaf nitrogen ([N]), phosphorus ([P]), soluble sugars and starch. Results: The chronosequence was characterised by decreasing R D, R L and A, reduced [N] and [P] and increasing M A as soil age increased. Light inhibition of R occurred across the chronosequence (mean inhibition = 16 %), resulting in ratios of R L:A being lower than for R D:A. Importantly, the degree of light inhibition differed across the chronosequence, being lowest at young sites and highest at old sites. This resulted in R L:A ratios being relatively constant across the chronosequence, whereas R D:A ratios increased with increasing soil age. Log-log R-A-M A-[N] relationships remained constant along the chronosequence. By contrast, relationships linking rates of leaf R to [P] differed among leaves with low vs high [N]:[P] ratios. Slopes of log-log bivariate relationships linking R L to A, M A, [N] and [P] were steeper than that for R D. Conclusions: Our findings have important implications for predictive models that seek to account for light inhibition of R, and for our understanding of how environmental gradients impact on leaf trait relationships © 2013 Springer Science+Business Media Dordrecht.

Owen K. Atkin [et al.].- Received: 8 July 2014, Accepted: 29 November 2014, Leaf dark respiration (Rdark) is an important yet poorly quantified component of the global carbon cycle. Given this, we analyzed a new global database of Rdark and associated leaf traits., Data for 899 species were compiled from 100 sites (from the Arctic to the tropics). Several woody and nonwoody plant functional types (PFTs) were represented. Mixed-effects models were used to disentangle sources of variation in Rdark., Area-based Rdark at the prevailing average daily growth temperature (T) of each site increased only twofold from the Arctic to the tropics, despite a 20°C increase in growing T (8–28°C). By contrast, Rdark at a standard T (25°C, Rdark25) was threefold higher in the Arctic than in the tropics, and twofold higher at arid than at mesic sites. Species and PFTs at cold sites exhibited higher Rdark25 at a given photosynthetic capacity (Vcmax25) or leaf nitrogen concentration ([N]) than species at warmer sites. Rdark25 values at any given Vcmax25 or [N] were higher in herbs than in woody plants., The results highlight variation in Rdark among species and across global gradients in T and aridity. In addition to their ecological significance, the results provide a framework for improving representation of Rdark in terrestrial biosphere models (TBMs) and associated land-surface components of Earth system models (ESMs).