Leaf Traits

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 toughne...

Here, we investigated the physiological and structural leaf responses of seedlings of two evergreen and two deciduous Quercus species, grown in a glasshouse and subjected to contrasted conditions of light (low, medium and high irradiance) and water (continuous watering vs 2-months drought).
The impact of drought on photosynthetic rate was strongest in high irradiance, while the impact of shade on photosynthetic rate was strongest with high water supply, contradicting the hypothesis of allocation trade-off.
Multivariate causal models were evaluated using d-sep method. The model that best fitted the dataset proposed that the variation in specific leaf area affects photosynthetic rate and leaf nitrogen concentration, and this trait determines stomatal conductance, which also affects photosynthetic rate.
Shade conditions seemed to ameliorate, or at least not aggravate, the drought impact on oak seedlings, therefore, the drought response on leaf performance depended on the light environment.