Interspecific covariation between stomatal density and other functional leaf traits in a local flora

Abstract

Despite the importance of stomata in leaf functioning, and despite the recent interest in interspecific leaf trait covariation in functional ecology, little is known about how stomatal density relates to other leaf traits in a broad interspecific context. This is especially important because stomatal density has been widely used to deduce temporal variation in atmospheric CO2 concentrations [CO2atm] from fossilized or herbarium leaves. We therefore measured stomatal density, specific leaf area (SLA) and its components, leaf thickness, and leaf chlorophyll content in both sun and shade leaves of 169 individuals from 52 angiosperm species in southwestern Quebec. Using mixed models, we show that stomatal density decreases allometrically with increasing SLA and chlorophyll content, and increases allometrically with increasing lamina thickness. The sun-shade contrast changes the intercepts, but not the slopes, of these relationships. It is important to take into consideration these relations when correlating stomatal density with [CO2], to avoid spurious interpretations.Résumé : Malgré l'importance des stomates dans le fonctionnement des plantes et malgré les récents intérêts pour la covariation interspécifique des traits foliaires en écologie fonctionnelle, peu est connu sur comment la densité stomatique est reliée aux autres traits foliaires. Ceci est particulièrement important parce que la densité stomatique a largement été utilisée pour déduire les variations dans le temps des concentrations de CO2 atmosphérique [CO2atm] à partir de feuilles fossilisées ou de feuilles d'herbiers. Cependant, la relation entre [CO2atm] et densité stomatique n'est pas claire et est incertaine. Nous avons donc mesuré la densité stomatique, la surface spécifique foliaire (SSF) et ses composantes, l'épaisseur des feuilles et la concentration de chlorophylle des feuilles, pour les feuilles de soleil et d'ombre, de 169 individus provenant de 52 espèces d'angiospermes dans le sud-ouest du Québec. À l'aide de modèles mixtes, nous montrons que la densité stomatique diminue allométriquement avec la SSF et avec la concentration de chlorophylle et qu'elle augmente allométriquement avec l'épaisseur des feuilles. Le contraste entre feuilles de soleil et feuilles d'ombre change les interceptes, mais pas les pentes. Il est important de prendre en considération ces relations quand la densité stomatique est corrélée avec [CO 2atm ], afin d'éviter des interprétations erronées.Mots-clés : SSF, densité stomatal, allométrie, l'ecologie comparée, épaisseur de la lame folaire, composantes de la variance.

Leaf photosynthetic, economics and hydraulic traits are decoupled among genotypes of a widespread species of eucalypt grown under ambient and elevatedCO2

“…There were, however, two notable exceptions. Among genotypes grown in eCO 2 , stomatal density shifted towards the leaf economics syndrome, consistent with previous reports of coordination between stomatal density, LMA and cell size (Loranger & Shipley 2010;Brodribb, Jordan & Carpenter 2013), while stomatal conductance shifted towards the hydraulic traits syndrome, and was in fact strongly correlated with VD across genotypes. This correlation between VD and stomatal conductance suggests some degree of coordination among genotypes between hydraulic supply and leaf water-use in response to growth in eCO 2 , even though VD was overall unresponsive to eCO 2 while stomatal conductance declined significantly.…”

Successional changes in functional composition contrast for dry and wet tropical forest

“…Thick leaves mostly have higher stomatal density (but see Bongers and Popma 1990) and lower chlorophyll contents (Loranger and Shipley 2010), are expensive to construct and associated with longer leaf lifespans (Reich et al 1991; but see Kitajima et al 2012). Lastly the importance of species that depend on animals for seed dispersal increases with tropical dry forest succession, as does the volume of the seeds.…”

Modeling leaf maximum net photosynthetic rate of Festuca pallescens, the dominant perennial grass of Patagonian pine-based silvopastoral systems

“…This response agrees with Farquhar and Sharkey (1982), who indicated that the higher photosynthetic rates of sun leaves are a result of both higher stomatal conductance and higher intrinsic photosynthetic capacity of the mesophyll at a given conductance. In general, an increase in light intensity results in an increase in stomatal density (Casson and Gray 2008;Loranger and Shipley 2010). Simultaneously, the higher mesophyll capacity of sun leaves reflects, at least in part, their higher concentration of Rubisco and other photosynthetic enzymes related with high nitrogen content (Givnish 1988).…”