Leaf surface traits contributing to wettability, water interception and uptake of above-ground water sources in shrubs of Patagonian arid ecosystems

Abstract

Background and Aims The eco-hydrological significance of leaf wetting due to atmospheric water in arid and semiarid ecosystems is not well understood. In these environments, the inputs of precipitation or dew formation resulting in leaf wetting have positive effects on plant functioning. However, its impact on plant water relations may depend on the degree of leaf surface wettability. In this study we evaluated leaf wettability and other leaf traits and its effects on foliar water uptake and canopy interception in plant species of a Patagonian steppe. We also studied how leaf traits affecting wettability vary seasonally from growing to dry season. Method Contact angle of a water droplet with the leaf surface, water adhesion, droplet retention angle, stomatal density, cuticular conductance, canopy interception and maximum foliar water uptake were determined in six dominant shrub species. Key results All species increased its wettability during the dry season and most species were considered highly wettable. The leaf surface had very high capacity to store and retain water. We found a negative correlation between foliar water uptake and leaf hydrophilia. Conclusions Despite the diversity of life forms including cushion shrubs and tall shrubs, as well as phenological variability, all species converged in similar seasonal changes in leaf traits which favor its wettability. Intercepted water by crowns and the extremely high capacity of retention of droplets on leaf surfaces can have a significant impact on eco-hydrological process in water limited ecosystems where most of the precipitation during the growing and the dry season may be dew or small rainfall events, which do not always increase soil water availability.

High potential for foliar water uptake in early stages of leaf development of three woody angiosperms

“…Leaf wettability is another crucial factor affecting FWU (Ali et al, 2022;Azad et al, 2015;Eller et al, 2013;Goldsmith et al, 2013;Gotsch et al, 2014;Gürsoy et al, 2017). It is substantially determined by the water-repellency of leaf surfaces, which is increased by the presence of thick cuticles, cuticle chemical properties, waxes, and glabrous surfaces (e.g., Cavallaro et al, 2022;Kupper et al, 2006;Roth-Nebelsick et al, 2022), while trichomes may decrease or increase the wettability of leaves (Fernández et al, 2014(Fernández et al, , 2017Pan et al, 2021).…”

Progression toward maximum leaf surface storage during the rainfall interception process

“…The large variability in data was shown in Figure 5 with generally increasing standard errors of the mean leaf inclination angles after the increasing number of drop impacts on the leaf surface. This finding may express the role of accumulated water following each drop impact on the differences in leaf morphology for each leaf sample (Cavallaro et al, 2022; Koch et al, 2008; Ou et al, 2023). As expected, as drop size increased, the variability of leaf inclination angles generally increased.…”

“…Leaf surface storage is the maximum amount of water retained on a leaf divided by the all‐sided surface area of the leaf (Holder, 2013). The water contributing to leaf surface storage can be lost to evaporation, absorbed into the leaf, or contribute to throughfall or stemflow as the smaller water drops on leaf surfaces coalesce to form larger water drops and move off the leaf (Cavallaro et al, 2022; Lenz et al, 2022; Nanko et al, 2013).…”

Phenotypic plasticity in leaf traits in response to experimental precipitation increase: Wettability, foliar water uptake and gas exchange

“…Some studies have argued that high wettability can negatively affect the plant function (e.g., increase pathogen establishment and reduce CO2 diffusion), such that wet environment should be select for less wettable leaves (Sase et al, 2008). Whereas a global analysis (Goldsmith et al, 2017) found low leaf wettability only in environment with low precipitation, recently, Cavallaro et al (2022) showed that Patagonian steppe species are highly wettable.…”