Variability in leaf wettability and surface water retention of main species in semiarid Loess Plateau of China

Abstract

Leaf wettability, adhesion or repulsion of water drops, varies greatly among species and plays an important role in plant-soil hydrological relations. This study aimed to examine the variability in leaf wettability among species in different habitats and growth periods, and their relationships with plant surface water retention in the semiarid Loess Plateau of China. The leaf adaxial and abaxial contact angles, the surface water retention of leaves and individual plants, and general plant traits of 68 species belonging to 28 families were examined from May to August in 2017. Results showed that leaf water contact angles ranged from 27.3°to 133.4°and leaves with higher contact angles normally had lower variation coefficients. Leaf wettability was affected by internal properties (including leaf side, family, and leaf age) and external conditions (growth period), whereas the life form and slope aspect did not show significant effects. There were 47 species having higher contact angles on adaxial than abaxial surfaces, and the differences were significant in 23 species. Gramineous and leguminous species were more unwettable than compositae and rosaceous species. New leaves were more unwettable than old leaves. Surface wettability increased from May-June to July-August period. Leaf wettability was positively correlated with leaf surface water retention and was the best predictor of individual plant surface water retention compared with other plant traits. Leaf wettability showed interspecific differences associated with family and growth stage and can be a considerable variable in predicting canopy interception and evaluating vegetation hydrological function in drought environments.

Surface water storage characteristics of main herbaceous species in semiarid Loess Plateau of China

“…The epicuticular wax layer constitutes the interface between leaf and atmosphere, and its main components have hydrophobic properties (Müller & Riederer, 2005). Our previous data also proved that leaves of gramineous and leguminous species were more water repellent (higher leaf contact angles) than those of compositae and rosaceous species (Xiong et al, 2018). Our previous data also proved that leaves of gramineous and leguminous species were more water repellent (higher leaf contact angles) than those of compositae and rosaceous species (Xiong et al, 2018).…”

“…When leaf contact angle is high, rainwater falling on leaf surface tend to drop more easily under the influences of gravity or any meteorological and biotic disturbances (Holder, 2013;Xiong et al, 2018).…”

“…Thus, dense epicuticular wax layers were generally associated with decreased leaf surface wettability (Koch, Bhushan, & Barthlott, 2009). Our previous data also proved that leaves of gramineous and leguminous species were more water repellent (higher leaf contact angles) than those of compositae and rosaceous species (Xiong et al, 2018). However, not all species belonging to the same family had similar leaf wettability.…”

An ecological perspective on water shedding from leaves

“…Seasonal changes of epicuticular wax load and composition are widespread and have been attributed to leaf ontogeny ( Jetter and Schäffer, 2001 ), temperature and water availability ( Ziv et al , 1982 ; Jordan et al , 1983 ), and erosion of wax crystals over time ( Neinhuis and Barthlott, 1998 ; Kang et al , 2018 ). Multiple studies report an increase in leaf wettability for broad-leaved trees towards the later part of the growth season, namely with increasing leaf age ( Neinhuis and Barthlott, 1998 ; Tranquada and Erb, 2014 ; Kang et al , 2018 ; Xiong et al , 2018 ).…”

Microbiomes of the Amazon forest: bacterial diversity and community structure in the phyllosphere, litter and soil

“…Additionally, high LWR in new leaves, as compared to old leaves (Xiong et al, 2018), may be due to the erosive effect of environmental factors, such as precipitation and atmospheric deposition, on the waxes of the leaf surface (Baker and Hunt, 1986). Our results are consistent with a study measuring leaf wettability that showed that LWR values are higher during dry periods when compared to rainy ones, due to the amount of particles deposited on the leaf surfaces during the dry season (Xiong et al, 2018). We have observed that new leaves have higher carbon concentration, probably due to the higher concentrations of organic compounds in waxes, partially explaining the increase of beta diversity in February 2016, as compared to July 2015.…”