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

View Article: PubMed Central - PubMed

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.

No MeSH data available.


Correlation coefficients between 12 species traits and relative growth rates, R at 1‐cm stem diameter. Species traits includes four leaf vein traits of (A) vein density (VLA), (B) the mean distance to nearest areole (DA), (C) the mean distance to nearest vein (DV), and (D) the vein areole distance ratio (VADR), and other six leaf traits of (E) leaf area (LA), (F) specific leaf area (SLA), (G) succulence, (H) thickness, and (I) mass‐based nitrogen and (J) phosphorus (Nmass and Pmass), and (K) wood density (WD) and (L) maximum height (Hmax). Each value of correlation coefficient, tau indicates the median of probability distribution of tau. In the case, that 95% interval of probability distribution does not include the zero, the correlation between species trait and relative growth rate is significant and then circle was filled. The downward line shows the decline of number of species compared. Species whose D95 is less than reference D was excluded from comparison and correlations were applied until the reference D which included 20 species for comparison.
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ece32311-fig-0001: Correlation coefficients between 12 species traits and relative growth rates, R at 1‐cm stem diameter. Species traits includes four leaf vein traits of (A) vein density (VLA), (B) the mean distance to nearest areole (DA), (C) the mean distance to nearest vein (DV), and (D) the vein areole distance ratio (VADR), and other six leaf traits of (E) leaf area (LA), (F) specific leaf area (SLA), (G) succulence, (H) thickness, and (I) mass‐based nitrogen and (J) phosphorus (Nmass and Pmass), and (K) wood density (WD) and (L) maximum height (Hmax). Each value of correlation coefficient, tau indicates the median of probability distribution of tau. In the case, that 95% interval of probability distribution does not include the zero, the correlation between species trait and relative growth rate is significant and then circle was filled. The downward line shows the decline of number of species compared. Species whose D95 is less than reference D was excluded from comparison and correlations were applied until the reference D which included 20 species for comparison.

Mentions: Size‐related changes in the correlations between species traits and RGR varied largely (Fig. 1). Of the four leaf vein traits, vein density (VLA) and the mean distance to the nearest vein (DV) were constantly significantly correlated with RGR for a wide range of reference stem diameter. VLA was positively and DV, a proxy of areole size, was negatively correlated with RGR from 1‐cm up to 21‐cm stem diameter (Fig 1A and C). The distance to the nearest areole (DA), a proxy for vein width, was significantly positively correlated with RGR only when trees are small at 1–4 cm diameter (Fig. 1B). The vein areole distance ratio (VADR), a measure of the complex structure of vein networks, was negatively correlated with RGR at small sizes < 7 cm and changed to nonsignificant at some sizes more than 7 cm (Fig. 1D). These results suggest that species with dense and/or wider veins, or smaller areoles tend to have faster RGR.


Linking leaf veins to growth and mortality rates: an example from a subtropical tree community
Correlation coefficients between 12 species traits and relative growth rates, R at 1‐cm stem diameter. Species traits includes four leaf vein traits of (A) vein density (VLA), (B) the mean distance to nearest areole (DA), (C) the mean distance to nearest vein (DV), and (D) the vein areole distance ratio (VADR), and other six leaf traits of (E) leaf area (LA), (F) specific leaf area (SLA), (G) succulence, (H) thickness, and (I) mass‐based nitrogen and (J) phosphorus (Nmass and Pmass), and (K) wood density (WD) and (L) maximum height (Hmax). Each value of correlation coefficient, tau indicates the median of probability distribution of tau. In the case, that 95% interval of probability distribution does not include the zero, the correlation between species trait and relative growth rate is significant and then circle was filled. The downward line shows the decline of number of species compared. Species whose D95 is less than reference D was excluded from comparison and correlations were applied until the reference D which included 20 species for comparison.
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ece32311-fig-0001: Correlation coefficients between 12 species traits and relative growth rates, R at 1‐cm stem diameter. Species traits includes four leaf vein traits of (A) vein density (VLA), (B) the mean distance to nearest areole (DA), (C) the mean distance to nearest vein (DV), and (D) the vein areole distance ratio (VADR), and other six leaf traits of (E) leaf area (LA), (F) specific leaf area (SLA), (G) succulence, (H) thickness, and (I) mass‐based nitrogen and (J) phosphorus (Nmass and Pmass), and (K) wood density (WD) and (L) maximum height (Hmax). Each value of correlation coefficient, tau indicates the median of probability distribution of tau. In the case, that 95% interval of probability distribution does not include the zero, the correlation between species trait and relative growth rate is significant and then circle was filled. The downward line shows the decline of number of species compared. Species whose D95 is less than reference D was excluded from comparison and correlations were applied until the reference D which included 20 species for comparison.
Mentions: Size‐related changes in the correlations between species traits and RGR varied largely (Fig. 1). Of the four leaf vein traits, vein density (VLA) and the mean distance to the nearest vein (DV) were constantly significantly correlated with RGR for a wide range of reference stem diameter. VLA was positively and DV, a proxy of areole size, was negatively correlated with RGR from 1‐cm up to 21‐cm stem diameter (Fig 1A and C). The distance to the nearest areole (DA), a proxy for vein width, was significantly positively correlated with RGR only when trees are small at 1–4 cm diameter (Fig. 1B). The vein areole distance ratio (VADR), a measure of the complex structure of vein networks, was negatively correlated with RGR at small sizes < 7 cm and changed to nonsignificant at some sizes more than 7 cm (Fig. 1D). These results suggest that species with dense and/or wider veins, or smaller areoles tend to have faster RGR.

View Article: PubMed Central - PubMed

ABSTRACT

A fundamental goal in ecology is to link variation in species function to performance, but functional trait&ndash;performance investigations have had mixed success. This indicates that less commonly measured functional traits may more clearly elucidate trait&ndash;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&#8208;occurring species in a subtropical forest. Size&#8208;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&#8208;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&#8208;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&#8208;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&#8208;use strategies, which dictate the demography and distributions of species.

No MeSH data available.