目的:干旱和半干旱生态系统中大气水分引起的叶片湿润的生态水文意义尚不清楚。在这些环境中,导致叶片润湿的降水或露水的输入对植物功能具有积极影响。然而,其对植物水分关系的影响可能取决于叶面润湿性的程度。在这项研究中,我们评估了巴塔哥尼亚草原植物物种的叶片润湿性和其他叶片性状及其对叶片吸水和冠层截留的影响。我们还研究了从生长到旱季影响润湿性的叶片性状如何随季节变化。
方法:水滴与叶片表面的接触角,水附着力,液滴保留角,气孔密度,角质层电导,确定了六种优势灌木种的冠层截留和最大叶面吸水。
结果:所有物种在旱季都增加了叶片的润湿性,大多数物种被认为是高度可湿性的。叶表面具有非常高的储存和保留水的能力。我们发现叶面水分吸收与叶片亲水性呈负相关。
结论:尽管生命形式多种多样,包括缓冲灌木和高大灌木,以及物候变化,所有物种在叶片性状上的季节性变化相似,有利于润湿性。树冠拦截的水和水滴在叶片表面的极高保留能力可能对水有限的生态系统中的生态水文过程产生重大影响,在水有限的生态系统中,大多数水源在生长和干旱季节可能是小降雨事件或露水,这并不总是增加土壤水分的可用性。
The ecohydrological 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.
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.
All species increased leaf 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.
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 that favour 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 water sources during the growing and the dry season may be small rainfall events or dew, which do not always increase soil water availability.