Data from: Biomechanical and leaf-climate relationships: a comparison of ferns and seed plants

Premise of the study: Relationships of leaf size and shape (physiognomy) with climate have been well characterized for woody non-monocotyledonous angiosperms (dicots), allowing the development of models for estimating paleoclimate from fossil leaves. More recently, petiole width of seed plants has been shown to scale closely with leaf mass. By measuring petiole width and leaf area in fossils, leaf mass per area (MA) can be estimated and an approximate leaf life span inferred. However, little is known about these relationships in ferns, a clade with a deep fossil record and with the potential to greatly expand the applicability of these proxies. Methods: We measured the petiole width, MA, and leaf physiognomic characters of 179 fern species from 188 locations across six continents. We applied biomechanical models and assessed the relationship between leaf physiognomy and climate using correlational approaches. Key results: The scaling relationship between area-normalized petiole width and MA differs between fern fronds and pinnae. The scaling relationship is best modeled as an end-loaded cantilevered beam, which is different from the best-fit biomechanical model for seed plants. Fern leaf physiognomy is not influenced by climatic conditions. Conclusions: The cantilever beam model can be applied to fossil ferns. The lack of sensitivity of leaf physiognomy to climate in ferns argues against their use to reconstruct paleoclimate. Differences in climate sensitivity and biomechanical relationships between ferns and seed plants may be driven by differences in their hydraulic conductivity and/or their differing evolutionary histories of vein architecture and leaf morphology.

Usage Notes
Leaf mass, leaf area, petiole width, and leaf physiognomic measurements of globally distributed ferns (Appendices S1a, S1b)Peppe et al_Appendices.xlsxFern images from Baylor University HerbariumZipped folder with images of ferns from Baylor Herbarium. Folder also includes ReadMe file and image key.Baylor ferns.zipFern images from Queensland HerbariumZipped folder with images of ferns from Queensland Herbarium. Folder also includes ReadMe file and image key.Queensland ferns.zipFern images from Te Papa HerbariumZipped folder with images of ferns from Te Papa Herbarium at the Museum of New Zealand Te Papa Tongarewa. Folder also includes ReadMe file and image key.Te Papa ferns (2).zipFern images from US National Herbarium (part 1)Zipped folder with images of ferns from USNH. Folder also includes ReadMe file and image key.USNH ferns_1.zipFern images from US National Herbarium (part 2)Zipped folder with images of ferns from USNH. Folder also includes ReadMe file and image key.USNH ferns_2.zipFern images from Waikato HerbariumZipped folder with images of ferns from Waikato Herbarium. Folder also includes ReadMe file and image key.Waikato ferns.zip

研究基础：木质双子叶植物（非单子叶被子植物）的叶片大小与形状（外貌）与气候之间的关系已被充分描述，从而允许从化石叶片中估计古气候的模型开发。近期研究表明，种子植物的叶柄宽度与叶片质量密切相关。通过测量化石中的叶柄宽度和叶片面积，可以估算叶片面积质量比（MA），并推断出叶片的大致寿命。然而，对于具有深厚化石记录且有可能大大扩展这些代理应用范围的马尾蕨类植物，关于这些关系的了解甚少。研究方法：我们对来自六大洲188个地点的179种马尾蕨植物的叶柄宽度、MA和叶片外貌特征进行了测量。我们应用生物力学模型，并采用相关方法评估了叶片外貌与气候之间的关系。关键结果：面积标准化叶柄宽度和MA之间的尺度关系在蕨类植物叶片和羽片之间存在差异。这种尺度关系最佳地以端加载悬臂梁模型来建模，这与种子植物的最佳生物力学模型不同。蕨类植物的外貌不受气候条件的影响。结论：悬臂梁模型可以应用于化石蕨类植物。叶片外貌对气候不敏感的事实，反驳了将其用于重建古气候的论点。蕨类植物与种子植物在气候敏感性和生物力学关系上的差异可能是由它们的水力传导性差异以及它们在叶脉结构及叶片形态演化历史上的不同所驱动的。使用说明：全球分布的马尾蕨植物的叶片质量、叶片面积、叶柄宽度和叶片外貌测量数据（附录S1a，S1b）。贝勒大学植物标本馆的蕨类植物图像。包含图像的压缩文件夹，还包括ReadMe文件和图像键。昆士兰州植物标本馆的蕨类植物图像。包含图像的压缩文件夹，还包括ReadMe文件和图像键。新西兰国家博物馆Te Papa Tongarewa的Te Papa植物标本馆的蕨类植物图像。包含图像的压缩文件夹，还包括ReadMe文件和图像键。美国国家植物标本馆（第一部分）的蕨类植物图像。包含图像的压缩文件夹，还包括ReadMe文件和图像键。美国国家植物标本馆（第二部分）的蕨类植物图像。包含图像的压缩文件夹，还包括ReadMe文件和图像键。瓦卡托植物标本馆的蕨类植物图像。包含图像的压缩文件夹，还包括ReadMe文件和图像键。