Leaf lifespan as a determinant of leaf structure and function among 23 amazonian tree species

Abstract

The relationships between resource availability, plant succession, and species' life history traits are often considered key to understanding variation among species and communities. Leaf lifespan is one trait important in this regard. We observed that leaf lifespan varies 30-fold among 23 species from natural and disturbed communities within a 1-km radius in the northern Amazon basin, near San Carlos de Rio Negro, Venezuela. Moreover, leaf lifespan was highly correlated with a number of important leaf structural and functional characterisues. Stomatal conductance to water vapor (g) and both mass and area-based net photosynthesis decreased with increasing leaf lifespan (r=0.74, 0.91 and 0.75, respectively). Specific leaf area (SLA) also decreased with increasing leaf lifespan (r=0.78), while leaf toughness increased (r=0.62). Correlations between leaf lifespan and leaf nitrogen and phosphorus concentrations were moderate on a weight basis and not significant on an area basis. On an absolute basis, changes in SLA, net photosynthesis and leaf chemistry were large as leaf lifespan varied from 1.5 to 12 months, but such changes were small as leaf lifespan increased from 1 to 5 years. Mass-based net photosynthesis (A/mass) was highly correlated with SLA (r=0.90) and mass-based leaf nitrogen (N/mass) (r=0.85), but area-based net photosynthesis (A/area) was not well correlated with any index of leaf structure or chemistry including N/area. Overall, these results indicate that species allocate resources towards a high photosynthetic assimilation rate for a brief time, or provide resistant physical structure that results in a lower rate of carbon assimilation over a longer time, but not both.

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

“…In this study, estimated values of leaf life span are consistent with those reported by Williams et al (1989), who observed that understory Piper species have leaf longevity greater than one year. Indeed, leaves with A mass of 62.2 nmol g −1 s −1 (this study) have leaf longevity of 15 (Reich et al, 1991) to 30 months (Poorter and Bongers, 2006), which suggests our leaf longevity estimate is rather conservative. In comparison with gap-demanding species, shade tolerant plants also have high LMA, leaves with a long life span, and synthetize large amount of antiherbivore metabolites (Valladares and Niinemets, 2008;Gommers et al, 2013).…”

Root tissue structure is linked to ecological strategies of grasses

“…Low tissue mass density in leaves is associated with a high specific leaf area, large total leaf area and fast growth, on the one hand (Garnier, 1992 ;Ryser & Lambers, 1995 ;Meerts & Garnier, 1996 ;Ryser & Aeschlimann, 1999), and with short life span and high resource losses on the other (Schla$ pfer & Ryser, 1996 ;Ryser & Urbas, 2000). Leaf toughness and high tensile strength are associated with slow growth and also with a high degree of mechanical stability of the leaves, which tend to be well protected against environmental hazards such as herbivory (Coley, 1983 ;Reich et al, 1991 ;Cornelissen et al, 1999). Hence, tissue mass density is an effective means of predicting the performance of plants along gradients of resource availability (Wilson et al, 1999) ; a low tissue mass density is characteristic of plants of productive habitats, a high tissue mass density is typical in plants of unproductive environments Studies on the ecological significance of tissue structure have mostly been restricted to aboveground organs, especially leaves.…”

Methods of assessing leaf‐fracture properties

“…Extensive literature exists relating the physical properties of leaves to their ecology, covering topics such as herbivory (Coley, 1983 ;Raupp, 1985 ;Nichols-Orians & Shultz, 1990 ;Choong, 1996), decomposition (Arsuffi & Suberkropp, 1984 ;Gallardo & Merino, 1993), sclerophylly (Medina et al, 1990 ;Choong et al, 1992 ;Turner, 1994) and leaf longevity (Reich et al, 1991). Although fracture properties are measured routinely in engineering, determining the fracture properties of plants, and of biomaterials in general, is complicated for the following reasons.…”