Regional-scale spatial heterogeneity in the Late Paleocene paratropical forests of the U.S. Gulf Coast

The study of spatial patterns in biotic compositional variability in deep time is key to understanding the macroecological response of species assemblages to global change. Globally warm climatic phases are marked by the expansion of megathermal climates into currently extra-tropical areas. However, there is currently little information on whether vegetation in these ‘paratropical’ regions resembled spatially modern tropical or extra-tropical biomes. In this paper we explore spatial heterogeneity in extra-tropical megathermal vegetation, using sporomorph (pollen and spore) data from the Late Paleocene Calvert Bluff and Tuscahoma formations of the formerly paratropical US Gulf Coast (Texas, Mississippi and Alabama). The dataset comprises 139 sporomorph taxa recorded from 56 samples. Additive diversity partitioning, non-metric multidimensional scaling, and cluster analysis show compositional heterogeneity both spatially and lithologically within the US Gulf Coastal Plain (GCP) microflora....

深时（deep time）生物组成变异性的空间格局研究，是理解物种集合对全球变化宏观生态响应的关键。全球暖期的特征是高温气候（megathermal climate）向当前亚热带以外区域扩张。然而，目前关于这些“副热带”（paratropical）区域的植被在空间上更接近现代热带还是亚热带以外生物群系的信息尚少。本文利用美国墨西哥湾沿岸（原副热带区域，包括得克萨斯州、密西西比州和亚拉巴马州）晚古新世Calvert Bluff组和Tuscahoma组的孢粉形态（sporomorph，即花粉与孢子）数据，探究亚热带以外高温植被的空间异质性。该数据集包含从56个样本中记录的139个孢粉形态分类群。additive多样性分割（additive diversity partitioning）、非度量多维尺度分析（non-metric multidimensional scaling）和聚类分析显示，美国墨西哥湾沿岸平原（GCP）微植物群在空间和岩性上均存在组成异质性……