Carbon concentration in the world's trees across climatic gradients

Abstract

Wood carbon (C) concentration is a key wood trait that varies widely among tree species, but our understanding of the factors governing this trait is limited, despite reason to hypothesize that wood C varies systematically across environmental gradients. We compiled a novel database of 1145 geo‐referenced wood C observations from 415 species, to elucidate climate correlates of wood C concentrations, and test if these relationships differ across tissue types and major taxonomic divisions (i.e. angiosperms vs gymnosperms). Climate variables, including mean annual temperature (MAT) and precipitation and temperature seasonality, are significantly correlated with wood C concentrations. Relationships between wood C and these variables differ across tissue types and taxonomic divisions, yet there is a negative relationship between wood C and MAT that exists across all tissues and species groups. Wood C concentrations in trees are influenced by climate, with experimental evidence (albeit scant) indicating that climate‐driven changes in lignin concentrations likely govern these relationships. Our study presents among the first lines of evidence indicating that wood C concentrations are correlated with environmental conditions, thereby enhancing our understanding of the potential adaptive significance of wood C variation in trees.

Size‐dependent intraspecific variation in wood traits has little impact on aboveground carbon estimates in a tropical forest landscape

“…In our study, topographic wetness had no effect on intraspecific variation in WSG and WCC. Our results are consistent with meta‐analysis studies conducted at regional or the global scales, which showed that WCC do not correlate with precipitation regimes (Ma et al, 2018; Paroshy et al, 2021). Thus, our finding suggest that these two wood traits may not well reflect species hydraulic strategies (Fortunel et al, 2014).…”

“…By contrast, global variations in precipitation and temperature have no consistent effect on WCC (Ma et al, 2018;Paroshy et al, 2021).…”

“…Conventional approaches to estimate tropical forest carbon stocks use either species (or genus) specific WSG estimates and most often a 0.47 fixed carbon concentration ratio (Thomas & Martin, 2012) recommended by the evaluation scheme of the Intergovernmental Panel on Climate Change (IPCC). If WSG or WCC values vary along environmental gradients (Ma et al, 2018; Paroshy et al, 2021), then using a single species‐ or generic‐specific value of these traits or rather overlooking intraspecific variation in WSG or WCC may result in biased estimates (Réjou‐Méchain et al, 2019). However, this topic remains little studied, particularly accounting for intraspecific variation in wood traits and the consequences for ecosystem functioning.…”

“…low soil fertility, high sand percentage, low topographic wetness index) favour species with denser wood (Fortunel et al, 2014; Gourlet‐Fleury et al, 2011; Muller‐Landau, 2004; Muscarella et al, 2020). By contrast, global variations in precipitation and temperature have no consistent effect on WCC (Ma et al, 2018; Paroshy et al, 2021). However, very few studies conducted across environmental gradients in tropical forests have so far accounted for intraspecific variation in WSG (Fortunel et al, 2020) or WCC (Gillerot et al, 2018; Kattge et al, 2020; Martin & Thomas, 2013; Weber et al, 2018).…”

Improving wood carbon fractions for multiscale forest carbon estimation

“…"For example, data from trees in boreal vs. temperate forests are now more readily differentiated. Based on this growing literature, in 2022 we published a global database of wood CFs (referred to as the Global Woody Tissue Carbon Concentration Database ([GLOWCAD]), containing more than 3,500 individual species-averaged wood CFs from 864 tree species across all forested biomes, based on data from 112 studies published between 2004 and 2022 (16).Georeferenced data points within GLOWCAD also allow for ner-scale biome and climate disaggregation of wood CFs(21) compared to the IPCC table (2006), including wood CFs for tropical, subtropical/Mediterranean, temperate, and boreal forests (Table 2).…”