Abstract Epiphytes living in the canopy face the problem of being exposed to varying levels of air humidity, temperature and insolation, according to both local climate and growing site conditions. This study addresses interrelationships between a) vertical distribution of Tillandsia species on phorophytes of Ilha-Grande Island in tropical Brazil; b) micrometeorological conditions at the different epiphyte habitats and growing sites; c) diurnal changes in plant water content and d) morphological traits of Tillandsia leaves with respect to absorptive scales. For this purpose, five vertical zones of different height and exposure were defined within the canopy, which are characterized by specific epiphyte associations. It was found that the Tillandsia species are heterogeneously distributed within tree canopies. The most exposed sites are colonized almost exclusively by T. usneoides whereas less exposed zones are settled by different assemblages of all other considered Tillandsia species. Microsite conditions (temperature and humidity) were shown to be substantially different, with quite extreme conditions at the sites preferred by T. usneoides. Despite its apparently stressful habitat, T. usneoides showed the lowest decrease of daily water content. All considered Tillandsia species differed significantly with respect to size and density of their absorptive scales. Also, density and size of scales differed within the leaves in a species-specific manner. Tillandsia usneoides was distinctly different from all other considered species by showing the longest scales and a high scale density which was uniform over the leaves. The results demonstrate the unique ability of T. usneoides to cope with drought stress. The outcomes support the assumption that leaf and scale morphology of Tillandsia are correlated with habitat. Probably, a dense mat of filiform leaves covered with scales showing long wing cells – as shown by T. usneoides – is particularly suitable for harvesting atmospheric water.

中文翻译：

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巴西格兰德岛树木上生长的不同种类铁兰的生境条件、空间分布和毛状体形态

摘要 根据当地气候和生长地点条件，生活在树冠中的附生植物面临着暴露于不同水平的空气湿度、温度和日照的问题。本研究探讨了以下之间的相互关系：a) 巴西热带 Ilha-Grande 岛叶状植物上的铁兰属物种的垂直分布；b) 不同附生植物栖息地和生长地点的微气象条件；c) 植物含水量的昼夜变化和 d) 铁兰叶在吸收尺度方面的形态特征。为此，在树冠内定义了五个不同高度和暴露的垂直区域，其特征是特定的附生植物协会。发现铁兰属物种在树冠内异质分布。最暴露的地点几乎完全由 T. usneoides 殖民，而较少暴露的区域则由所有其他考虑的铁兰物种的不同组合定居。微型场地条件（温度和湿度）显示出显着不同，在 T. usneoides 首选的场地条件非常极端。尽管其栖息地显然压力很大，但 T. usneoides 的每日含水量下降幅度最小。所有被考虑的铁兰物种在其吸收鳞片的大小和密度方面都存在显着差异。此外，叶片内鳞片的密度和大小因物种而异。Tillandsia usneoides 与所有其他考虑的物种明显不同，因为它显示出最长的鳞片和在叶子上均匀的高鳞片密度。结果证明了 T. usneoides 应对干旱胁迫的独特能力。结果支持了铁兰的叶子和鳞片形态与栖息地相关的假设。很可能，如 T. usneoides 所示，覆盖有鳞片的丝状叶子致密垫，显示出长翼细胞——特别适合收集大气水。