Abstract. Because CO2 diffuses 10000 times more slowly through water than air, there may be strong selective pressure for increased water repellency in terrestrial plant leaves. In the present study, leaf trichomes appeared to have a strong influence on leaf water repellency (i.e. degree of water droplet formation on the leaf surface) as well as the retention of droplets on the leaf. Based upon evaluation of 38 plant species from 21 families, we found that leaves with trichomes were more water repellent, especially where trichome density was greater than 25mm2. However, droplet repellency and retention were both high in some species where trichomes entrapped droplets. Finally, the lensing effects of water droplets on leaf surfaces increased incident sunlight by over 20‐fold directly beneath individual droplets. These results may have important implications for such processes as stomatal function, whole leaf photosynthesis, and transpiration for a large variety of plant species.

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The frequency and duration of water on leaf surfaces have important consequences for plant growth and photosynthetic gas exchange. The objective of the present study was to compare the frequency and duration of leaf wetness under natural field conditions among species and to identify variation in structural features of leaves that may reduce surface wetness. During June-Septemher 1992 in the central Rocky Mountains (USA), natural leaf wetting due to rain and dewfall was observed on 79 of 89 nights in open meadow habitats compared to only 29 of 89 nights in the understorey. Dew formation occurred at relative humidities that were often well below 100% because of radiational heat exchange with cold night skies and low wind speeds (< 0-5 m s~*). A survey of 50 subalpine/montane species showed that structural characteristics associated with the occurrence and duration of leaf surface wetness differed among species and habitats. Both adaxial and abaxial surfaces accumulated moisture during rain and dewfall events. Leaf surfaces of open-meadow species were less wettable {P = 0-008), and had lower droplet retention (F = 0-015) and more stomata {P = 0-017) than adjacent understorey species. Also, leaf trichomes reduced the area of leaf surface covered by moisture. Ecophysiological importance is suggested by the high frequency of leaf wetting events in open microsites, influences on growth and gas exchange, and correspondence between leaf surface wettability and habitat.

The ability to effectively exchange information and develop trusting, collaborative relationships across disciplinary boundaries is essential for 21st century scientists charged with solving complex and large‐scale societal and environmental challenges, yet these communication skills are rarely taught. Here, we describe an adaptable training program designed to increase the capacity of scientists to engage in information exchange and relationship development in team science settings. A pilot of the program, developed by a leader in ecological network science, the Global Lake Ecological Observatory Network (GLEON), indicates that the training program resulted in improvement in early career scientists’ confidence in team‐based network science collaborations within and outside of the program. Fellows in the program navigated human‐network challenges, expanded communication skills, and improved their ability to build professional relationships, all in the context of producing collaborative scientific outcomes. Here, we describe the rationale for key communication training elements and provide evidence that such training is effective in building essential team science skills.

The objective of this study was to investigate patterns of surface features of leaves related to susceptibility to wetness for plants along a strong precipitation gradient. Leaf wettability and droplet retention were examined for leaves of 37 species (representing 28 families) occurring in steppe, ecotone, and temperate rain forest habitats along a steep moisture gradient in northwestern Patagonia, Argentina. Morphological and structural characteristics of leaves significantly affected leaf surface wetness, and these characteristics varied between habitats. Typically, leaves had more stomata on abaxial than adaxial leaf surfaces (P < 0:0001). Droplet retention and leaf wettability (u) were negatively correlated (Spearman r ¼ À0:694; P < 0:0001). Leaves in dry habitats tended to be less wettable and less likely to retain droplets on the leaf surface; however, overall differences were not significant. The presence of trichomes significantly reduced wettability (P < 0:05). The high frequency and natural variability of wetting events in these and a great variety of other habitats, coupled with the large range in surface wettability among plant species and the potentially strong effects on photosynthesis, growth, and pathogen infections, suggest an important evolutionary avenue related to the dynamics of water on leaf surfaces.

Nothofagus pumilio (Poepp. et Endl.) Krasser is a broadleaved deciduous tree that dominates high-elevation forests in the southern Andes. We evaluated the degree to which differences in stomatal density and physiological traits (net assimilation, conductance and water use efficiency) were related to environmental and genetic influences with elevation by comparing plants growing under field and common garden conditions. Low-elevation leaves under field conditions had fewer stomata, although this pattern was not maintained in the common garden. Assimilation rates were >40% higher for high-elevation plants in the field, and 18% higher in the common garden, than those for low-elevation plants. In addition, under field conditions high-elevation plants tended to have higher stomatal conductance and lower instantaneous water use efficiency than did low-elevation plants; however, these differences were not significant in the common garden. Thus, assimilation seems to be under genetic control whereas ecophysiological traits related to the use of water appear to be more responsive to environmental cues. Our results suggest that plants growing along elevational gradients may show complex ecophysiological patterns. These patterns may be acquired by genetically driven responses to conditions that are fixed throughout the life span of individuals, such as soil nutrients. Also plastic adjustments may favour opportunistic use of available water during the dry season, particularly under Mediterranean-type climate regimes with summer drought.

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