Linking leaf veins to growth and mortality rates: an example from a subtropical tree community

Abstract

A fundamental goal in ecology is to link variation in species function to performance, but functional trait–performance investigations have had mixed success. This indicates that less commonly measured functional traits may more clearly elucidate trait–performance relationships. Despite the potential importance of leaf vein traits, which are expected to be related to resource delivery rates and photosynthetic capacity, there are few studies, which examine associations between these traits and demographic performance in communities. Here, we examined the associations between species traits including leaf venation traits and demographic rates (Relative Growth Rate, RGR and mortality) as well as the spatial distributions of traits along soil environment for 54 co‐occurring species in a subtropical forest. Size‐related changes in demographic rates were estimated using a hierarchical Bayesian approach. Next, Kendall's rank correlations were quantified between traits and estimated demographic rates at a given size and between traits and species‐average soil environment. Species with denser venation, smaller areoles, less succulent, or thinner leaves showed higher RGR for a wide range of size classes. Species with leaves of denser veins, larger area, cheaper construction costs or thinner, or low‐density wood were associated with high mortality rates only in small size classes. Lastly, contrary to our expectations, acquisitive traits were not related to resource‐rich edaphic conditions. This study shows that leaf vein traits are weakly, but significantly related to tree demographic performance together with other species traits. Because leaf traits associated with an acquisitive strategy such as denser venation, less succulence, and thinner leaves showed higher growth rate, but similar leaf traits were not associated with mortality, different pathways may shape species growth and survival. This study suggests that we are still not measuring some of key traits related to resource‐use strategies, which dictate the demography and distributions of species.

An extensive suite of functional traits distinguishes Hawaiian wet and dry forests and enables prediction of species vital rates

“…Our study also confirmed the hypothesis that stratifying by plant size improved the frequency of correlations of vital rates with given traits. Stratifying by size has previously been shown to improve resolution of correlations of RGR and m with traits such as vein densities, LA, LMA, SWC, LT, N mass and P mass , WD and H max (Iida et al., , ; Prado‐Junior et al., ), and our study expanded this finding to a wider range of traits. Stratifying by size reduces the confounding influence of ontogenetic shifts in vital rates on cross‐species comparisons (Hérault et al., ).…”

“…Several novel trait correlations were found with mean RGRs and m across species that were expected from theory and that have potential for generality, including the relationships of RGR dbh , RGR biom and/or m to and d , and several relationships were confirmed, such as with H max , LMA and WD, that were reported in previous studies of temperate (Iida et al., ) and/or tropical forests (Finegan et al., ; Hérault et al., ; Liu et al., ; Wright et al., ). The contrasting correlations of traits with m between the MWF and LDF, such as LMA and (Figure a,b), and the correlations of traits with m in one but not the other forest, such as for P mass and LA (Figure c,d), highlight the context dependence of trait–vital rate relationships.…”

“…Hawaiian forests also showed contrasting relationships of certain traits to vital rates than previously reported. For example, vein density contributes mechanistically to greater hydraulic conductance, photosynthetic productivity and RGR across diverse species, all else being equal (Brodribb & McAdam, ; Iida et al., ; Li et al., 2015a; Sack & Frole, ; Sack & Scoffoni, ; Sack et al., ; Scoffoni et al., ). However, RGR was negatively related to vein density across the species of both forests.…”

“…TA B L E 2 (Continued) density and dry matter content (Iida et al, 2016;Niinemets, 2001); N:P (Elser et al, 2000); and WD (Philipson et al, 2014;Visser et al, 2016;Wright et al, 2010). We also tested whether trait relationships with vital rates differed between forests (Kobe & Coates, 1997;Lusk, Reich, Montgomery, Ackerly, & Cavender-Bares, 2008).…”

“…Fourth, we hypothesized that across species, RGR and m would be positively correlated due to life-history trade-offs, and parallel associations with given traits (Kitajima, 1994;Philipson et al, 2014;Russo et al, 2010;Visser et al, 2016;Wright et al, 2010). Further, we hypothesized that RGR and m would relate positively to photosynthetic rate (Donovan & Ehleringer, 1994;); leaf area (Iida et al, 2016), N and P concentrations (Iida et al, 2016;Osone, Ishida, & Tateno, 2008); the sizes and numbers of stomata (Hetherington & Woodward, 2003;Wang et al, 2015); maximum stomatal conductance and vein densities (Hetherington & Woodward, 2003;Iida et al, 2016), and negatively to LMA (…”