Physiological and structural tradeoffs underlying the leaf economics spectrum

Abstract

The leaf economics spectrum (LES) represents a suite of intercorrelated leaf traits concerning construction costs per unit leaf area, nutrient concentrations, and rates of carbon fixation and tissue turnover. Although broad trade-offs among leaf structural and physiological traits have been demonstrated, we still do not have a comprehensive view of the fundamental constraints underlying the LES trade-offs. Here, we investigated physiological and structural mechanisms underpinning the LES by analysing a novel data compilation incorporating rarely considered traits such as the dry mass fraction in cell walls, nitrogen allocation, mesophyll CO diffusion and associated anatomical traits for hundreds of species covering major growth forms. The analysis demonstrates that cell wall constituents are major components of leaf dry mass (18-70%), especially in leaves with high leaf mass per unit area (LMA) and long lifespan. A greater fraction of leaf mass in cell walls is typically associated with a lower fraction of leaf nitrogen (N) invested in photosynthetic proteins; and lower within-leaf CO diffusion rates, as a result of thicker mesophyll cell walls. The costs associated with greater investments in cell walls underpin the LES: long leaf lifespans are achieved via higher LMA and in turn by higher cell wall mass fraction, but this inevitably reduces the efficiency of photosynthesis.

Photoprotective Strategies of Mediterranean Plants in Relation to Morphological Traits and Natural Environmental Pressure: A Meta-Analytical Approach

“…As expected, the morphological and biochemical characteristics should them adjust along seasons and years. For this reason, evergreens require more rigid mesophyll structure (Onoda et al, 2017) or greater investment in photoprotection (with higher contents of VAZ and α-Toc) than deciduous, as we shown in this study (Figure 2). Sclerophyllous leaves, a trait that is closely related to evergreen strategy, also showed the same pattern.…”

“…Despite structural filtering of light and efficient protection against water lost of most sclerophyllous leaves, it has been proposed the existence of a trade-off between photosynthesis and LMA in relation with Leaf Economics Spectrum (Wright et al, 2004). It seems that mesophyll conductance (g s ) may be the most limiting factor for carbon assimilation, showing those leaves with highest LMA values, a reduction in CO 2 diffusion to the carboxylation sites (Flexas et al, 2014; Onoda et al, 2017; Peguero-Pina et al, 2017). This implies that plants with high LMA will generally show lower photosynthetic capacity and thus, may require higher levels of photoprotective metabolites.…”

Litter moisture adsorption is tied to tissue structure, chemistry, and energy concentration

“…We observed large variation in litter chemical and physical traits (i.e., 69 variation in SLA), but this range was considerably smaller than range of variation used to uncover the robust empirical relationships within the leaf economics literature over the last several decades (i.e., 259 variation in SLA; Onoda et al 2017). We observed large variation in litter chemical and physical traits (i.e., 69 variation in SLA), but this range was considerably smaller than range of variation used to uncover the robust empirical relationships within the leaf economics literature over the last several decades (i.e., 259 variation in SLA; Onoda et al 2017).…”

A global comparison of the nutritive values of forage plants grown in contrasting environments

“…thicker cell walls and increased concentrations of lignin) in plants (Kering et al 2011), and also promotes species turnover by favouring taller, slow-growing species which invest more energy in structural support and defence, and invest less energy in the growth of leaves (Jégo et al 2013; Waghorn and Clark 2004). Trade-offs between the proportion of cell walls in leaves, which promotes longevity, and photosynthetic proteins, which promotes rapid growth, has been demonstrated across many plant species (Onoda et al 2017), whilst leaf longevity and associated traits generally increase under warmer conditions (Wright et al 2004). …”