Cruz-Silva Esmeralda, Harrison Sandy P, Marinova Elena, Prentice I Colin
School of Archaeology, Geography & Environmental Science Reading University Reading UK.
Laboratory for Archaeobotany Baden-Württemberg Cultural Heritage State Office Geienhofen-Hemmenhofen Germany.
J Biogeogr. 2022 Jul;49(7):1381-1396. doi: 10.1111/jbi.14448. Epub 2022 Jun 15.
Biomisation has been the most widely used technique to reconstruct past regional vegetation patterns because it does not require an extensive modern pollen dataset. However, it has well-known limitations including its dependence on expert judgement for the assignment of pollen taxa to plant functional types (PFTs) and PFTs to biomes. Here we present a new method that combines the strengths of biomisation with those of the alternative dissimilarity-based techniques.
The Eastern Mediterranean-Black Sea Caspian Corridor (EMBSeCBIO).
Plants.
Modern pollen samples, assigned to biomes based on potential natural vegetation data, are used to characterize the within-biome means and standard deviations of the abundances of each taxon. These values are used to calculate a dissimilarity index between any pollen sample and every biome, and thus assign the sample to the most likely biome. We calculate a threshold value for each modern biome; fossil samples with scores below the threshold for all modern biomes are thus identified as non-analogue vegetation. We applied the new method to the EMBSeCBIO region to compare its performance with existing reconstructions.
The method captured changes in the importance of individual taxa along environmental gradients. The balanced accuracy obtained for the EMBSeCBIO region using the new method was better than obtained using biomisation (77% vs. 65%). When the method was applied to high-resolution fossil records, 70% of the entities showed more temporally stable biome assignments than obtained using biomisation. The technique also identified likely non-analogue assemblages in a synthetic modern dataset and in fossil records.
The new method yields more accurate and stable reconstructions of vegetation than biomisation. It requires an extensive modern pollen dataset, but is conceptually simple, and avoids subjective choices about taxon allocations to PFTs and PFTs to biomes.
生物化是重建过去区域植被格局最广泛使用的技术，因为它不需要大量的现代花粉数据集。然而，它有众所周知的局限性，包括在将花粉分类群分配到植物功能类型（PFTs）以及将PFTs分配到生物群落时依赖专家判断。在此，我们提出一种新方法，该方法结合了生物化与基于相异性的替代技术的优势。
东地中海 - 黑海里海走廊（EMBSeCBIO）。
植物。
基于潜在自然植被数据分配到生物群落的现代花粉样本，用于表征每个分类群在生物群落内的丰度均值和标准差。这些值用于计算任何花粉样本与每个生物群落之间的相异性指数，从而将样本分配到最可能的生物群落。我们为每个现代生物群落计算一个阈值；得分低于所有现代生物群落阈值的化石样本因此被识别为非类似植被。我们将新方法应用于EMBSeCBIO区域，以将其性能与现有重建方法进行比较。
该方法捕捉到了单个分类群沿环境梯度重要性的变化。使用新方法为EMBSeCBIO区域获得的平衡准确率优于使用生物化方法（77%对65%）。当该方法应用于高分辨率化石记录时，70%的实体显示出比使用生物化方法更具时间稳定性的生物群落分配。该技术还在一个合成现代数据集中和化石记录中识别出可能的非类似组合。
新方法比生物化方法能产生更准确、更稳定的植被重建。它需要大量的现代花粉数据集，但概念简单，并且避免了关于将分类群分配到PFTs以及将PFTs分配到生物群落的主观选择。
