1. Plant functional traits impact the fitness and environmental niche of plants. Major plant functional types have been characterized by their trait spectrum, and the environmental and phylogenetic imprints on traits have advanced several ecological fields. Yet, very few trait data on epiphytes, which represent almost 10% of vascular plants, are available.
2. We collated 76,561 trait observations for 2,882 species of vascular epiphytes and compared these to non-epiphytic herbs and trees to test hypotheses related to how the epiphytic habit affects traits, and if epiphytes occupy a distinct region in the global trait space. We also compared variation in traits among major groups of epiphytes, and investigated the coordination of traits in epiphytes, ground-rooted herbs and trees.
3. Epiphytes differ from ground-rooted plants mainly in traits related to water relations. Unexpectedly, we did not find lower leaf nutrient concentrations, except for nitrogen. Mean photosynthetic rates are much lower than in ground-rooted plants and lower than expected from the nitrogen concentrations. Trait syndromes clearly distinguish epiphytes from trees and from most non-epiphytic herbs.
4. Among the three largest epiphytic taxa, orchids differ from bromeliads and ferns mainly by having smaller and more numerous stomata, while ferns differ from bromeliads by having thinner leaves, higher nutrient concentrations, and lower water content and water use efficiency.
5. Trait networks differ among epiphytes, herbs and trees. While all have central nodes represented by SLA and mass-based photosynthesis, in epiphytes, traits related to plant water relations have stronger connections, and nutrients other than potassium have weaker connections to the remainder of the trait network. Whereas stem-specific density reflects mechanical support related to plant size in herbs and trees, in epiphytes it mostly reflects water storage and scales with leaf water content.
6. Synthesis. Our findings advance our understanding of epiphyte ecology, but we note that currently mainly leaf traits are available. Important gaps are root, shoot and whole plant, demographic and gas exchange traits. We suggest how future research might use available data and fill data gaps.

中文翻译：

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将维管附生植物放在特征图上

1. 植物功能性状影响植物的适应性和环境生态位。主要植物功能类型已通过其性状谱表征，性状上的环境和系统发育印记已经推进了多个生态领域。然而，关于附生植物（占维管植物近 10%）的性状数据很少可用。
2. 我们整理了 2,882 种维管附生植物的 76,561 个性状观察结果，并将其与非附生草本植物和树木进行比较，以检验与附生习性如何影响性状以及附生植物是否在全球性状空间中占据不同区域相关的假设。我们还比较了主要附生植物群的性状变异，并研究了附生植物、地根草本植物和树木中性状的协调性。
3. 附生植物与地根植物的主要区别在于与水关系有关的性状。出乎意料的是，除氮外，我们没有发现较低的叶片养分浓度。平均光合速率远低于地根植物，也低于氮浓度的预期值。性状综合征清楚地将附生植物与树木和大多数非附生草本植物区分开来。
4. 在三大附生类群中，兰花与凤梨科和蕨类植物的区别主要在于气孔更小、数量更多，而蕨类植物与凤梨科植物的区别在于叶片更薄、营养浓度更高、水分含量和水分利用效率更低。
5. 附生植物、草本植物和树木的特征网络不同。虽然所有植物都有以 SLA 和基于质量的光合作用为代表的中心节点，但在附生植物中，与植物水分关系相关的性状具有更强的联系，而钾以外的营养物质与性状网络的其余部分的联系较弱。虽然茎比密度反映了与草本植物和树木中植物大小相关的机械支持，但在附生植物中，它主要反映了水分储存和叶片含水量的规模。
6. 合成。我们的研究结果促进了我们对附生植物生态学的理解，但我们注意到目前主要是叶子特征可用。重要的差距是根、芽和整株植物、人口和气体交换特征。我们建议未来的研究如何使用可用数据并填补数据空白。