Global patterns of leaf mechanical properties

Abstract

Leaf mechanical properties strongly influence leaf lifespan, plant-herbivore interactions, litter decomposition and nutrient cycling, but global patterns in their interspecific variation and underlying mechanisms remain poorly understood. We synthesize data across the three major measurement methods, permitting the first global analyses of leaf mechanics and associated traits, for 2819 species from 90 sites worldwide. Key measures of leaf mechanical resistance varied c. 500-800-fold among species. Contrary to a long-standing hypothesis, tropical leaves were not mechanically more resistant than temperate leaves. Leaf mechanical resistance was modestly related to rainfall and local light environment. By partitioning leaf mechanical resistance into three different components we discovered that toughness per density contributed a surprisingly large fraction to variation in mechanical resistance, larger than the fractions contributed by lamina thickness and tissue density. Higher toughness per density was associated with long leaf lifespan especially in forest understory. Seldom appreciated in the past, toughness per density is a key factor in leaf mechanical resistance, which itself influences plantanimal interactions and ecosystem functions across the globe.

Weak coordination among petiole, leaf, vein, and gas‐exchange traits across Australian angiosperm species and its possible implications

“…(2011). Briefly, calculated petiole conductance can be expressed as: K P  =  K X ·A , where K X  = the xylem‐specific conductivity and A = the cross‐sectional area of xylem.…”

Changing gears during succession: shifting functional strategies in young tropical secondary forests

“…Later in succession, CWMs were closely associated with a resource conservation strategy, i.e., high D max , WD (for the sapling size class), and leaf toughness and low A mass (Reich 2014). Trait values associated with this functional strategy are strongly correlated with greater shade and herbivory tolerance (Kitajima and Poorter 2010;Lasky et al 2014;Onoda et al 2011;Reich et al 2003), thus facilitating persistence in abiotic and biotic conditions in which resource acquisitive species would not survive (Kitajima 1994;Rees et al 2001;Wright 2002).…”

“…Variation in functional traits illustrates how species acquire and utilize resources to grow, reproduce, and tolerate herbivores, pathogens, and mechanical damage (Adler et al 2013;Chave et al 2009;Onoda et al 2011;Reich et al 1997;Wright et al 2004). In general, species with low leaf mass area (LMA), high foliar N content, short leaf lifespans, and low wood density rapidly convert light energy to carbon, and thus growth, at the cost of greater susceptibility to herbivore and pathogen attacks and reduced shade and drought tolerance (Adler et al 2013;Reich 2014;Reich et al 1997).…”

“…Thick veins were excised prior to being positioned firmly between two plates to minimize plastic deformation (Sanson et al 2001). Leaf toughness was normalized by dividing force (N) by the circumference of the piston (Onoda et al 2011).…”

Plants and Light Manipulation: The Integrated Mineral System in Okra Leaves

“…Silica is often considered to have a structural/defensive function 20, 21, 22. Mechanical properties of leaves are studied for leaves as whole units, with no special attention to the presence of silica or the other minerals 23, 24, 25…”