Epiphyte is a unique component of forest diversity vulnerable to changing environments. Characterizing variations in functional traits of epiphytes across dry and wet seasons can enhance our understanding their strategies to environments. We measured and assessed variations of 14 leaf functional traits responding to water conditions for epiphytic pteridophytes (EP) and epiphytic angiosperms (EA) across dry and wet seasons in a tropical cloud forest. Results showed that leaf dry weight (LDW) and stomatal length (SL) of EP were significantly higher than EA, while leaf water content (LWC) of EA was significantly higher than EP. The SL, stomatal density (SD), upper epidermis thickness (UET), lower epidermis thickness (LET), palisade tissue thickness (PT), spongy tissue thickness (ST), and leaf thickness (LT) of EP and EA were significantly higher in wet season than dry season. The variance of stomatal and anatomical traits explained by season types (0.24–0.78) was higher than plant groups (0.0–0.25), while the variance of LDW and LWC explained by plant groups (0.12–0.40) was higher than season types (0.0–0.29). Principal component analysis and correlation analyses showed that SL, stomatal index, UET, ST, LET, and LT were the key traits reflecting epiphyte adaptation to dry season, as well as that LWC and leaf density were the key traits in wet season. Our results suggest that the different taxonomic groups exhibit divergent strategies responding to water differences. Great variations in leaf traits to dry seasons are predicted that vascular epiphytes, especially pteridophytes, are prone to disappear with drought events.

中文翻译：

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热带云雾林附生蕨类植物和被子植物应对干湿季节的不同策略

附生植物是森林多样性的独特组成部分，容易受到环境变化的影响。表征不同旱季和雨季附生植物功能性状的变化可以增强我们对它们对环境的策略的理解。我们测量和评估了热带云林中 14 种叶片功能性状对附生蕨类植物 (EP) 和附生被子植物 (EA) 水分条件的变化。结果表明，EP的叶片干重（LDW）和气孔长度（SL）显着高于EA，而EA的叶片含水量（LWC）显着高于EP。SL、气孔密度（SD）、上表皮厚度（UET）、下表皮厚度（LET）、栅栏组织厚度（PT）、海绵组织厚度（ST）、EP 和 EA 的叶片厚度（LT）在雨季显着高于旱季。季节类型解释的气孔和解剖性状方差（0.24-0.78）高于植物组（0.0-0.25），而植物组解释的LDW和LWC方差（0.12-0.40）高于季节类型（0.0） –0.29）。主成分分析和相关分析表明，SL、气孔指数、UET、ST、LET和LT是反映附生植物适应旱季的关键性状，LWC和叶片密度是雨季的关键性状。我们的结果表明，不同的分类群对水的差异表现出不同的策略。预测干旱季节叶片性状的巨大变化，维管附生植物，尤其是蕨类植物，容易随着干旱事件消失。