Research review. Components of leaf dry mass per area – thickness and density – alter leaf photosynthetic capacity in reverse directions in woody plants

Abstract

The relationships of foliage assimilation capacity per unit area (P P max ) with leaf dry mass per unit area (LMA) and nitrogen content per unit area (N P ) differ between species and within species grown in different habitats. To gain a more mechanistic insight into the dependencies of P P max on LMA and N P , this literature study based on 597 species from a wide range of earth biomes with woody vegetation examines the relations between leaf photosynthetic capacity and the components of LMA (leaf density (D, dry mass per volume) and thickness (T )), and also the correlations of D and T with leaf nitrogen content and fractional leaf volumes in different tissues. Across all species, P P max varied 12-fold and photosynthetic capacity per unit dry mass (P m max ) 16-fold, N P 12-fold, and nitrogen per unit dry mass (N m ) 13-fold, LMA 46-fold, D 13-fold, and T 35-fold, indicating that foliar morphology was more plastic than foliar chemistry and assimilation rates. Although there were strong positive correlations between P P max and N P , and between P m max and N m , leaf structure was a more important determinant of leaf assimilation capacities. P P max increased with increasing LMA and T, but was independent of D. By contrast, P m max scaled negatively with LMA because of a negative correlation between P m max and D, and was poorly related to T. Analysis of leaf nitrogen and tissue composition data indicated that the negative relationship between D and P m max resulted from negative correlations between D and N m , D and volumetric fraction of leaf internal air space, and D and symplasmic leaf fraction. Thus, increases in leaf density bring about (1) decreases in assimilative leaf compounds, and (2) extensive modifications in leaf anatomy that may result in increases in intercellular transfer resistance to CO # . Collectively, (1) and (2) lead to decreased P m max , and also modify P P max versus LMA relationships.

Do soil fertilization and forest canopy foliage affect the growth and photosynthesis of Amazonian saplings?

“…herbivory; Endara and Coley, 2011). The slight trend of A max to respond to changes in LT but not to variation in LMA suggests that leaf density (the other component of LMA) negatively affects A max , as previously reported for the A mass /leaf density relationship (Niinemets, 1999).…”

Diversity of deciduousness and phenological traits of key Indian dry tropical forest trees

“…Significant relationships of LMA and wood density with leaf strategy index and with the extent of deciduousness, noticed in our study, suggest their significant role during both growth and deciduousness periods. Species with high LMA tend to have long average leaf life span and slow photosynthetic rates (Field and Mooney, 1986;Niinemets, 1999). Mass based assimilation decreases with increasing leaf life span (which is reciprocal to deciduousness duration, as in our study) and LMA (Prior et al, 2003;Reich et al, 1992).…”

Global leaf trait estimates biased due to plasticity in the shade

“…This means that the derived trait relationships of the global leaf economic spectrum are probably dependent on the extent to which observed data in existing large-scale plant databases represent high-light conditions. Here, using an extensive worldwide database of within-canopy gradients of key physiological, structural and chemical traits 3 , along with three different global trait databases 4,5 , we show that: (1) accounting for light-driven trait plasticity can reveal novel trait relationships, particularly for highly plastic traits (for example, the relationship between net assimilation rate per area (A a ) and leaf mass per area (LMA)); and (2) a large proportion of leaf traits in current global plant databases reported as measured in full sun were probably measured in the shade. The results show that even though the majority of leaves exist in the shade, along with a large proportion of observations, our current understanding is too focused on conditions in the sun.…”

“…It is also unclear to what extent existing large-scale vegetation plant databases used for developing the leaf economics spectrum 2 , parameterizing land surface models 8,9 and in comparisons to remote sensing approaches 18,19 actually include specimens sampled at low light. In this study we examine these issues using a light-standardized canopy trait plasticity (CANTRIP 3,20 ) database of leaf structural, chemical and physiological traits 3 , along with a combined dataset consisting of three previously published global leaf trait databases (the Poorter 4 , Niinemets 5 and Glopnet 2 databases, henceforth the PNG dataset, see Methods) that do not account for the effect of light-driven trait plasticity 2,4,5 . We use the combined datasets to examine the effect of low light during development (i.e.…”