Plant fossils from the Early and Middle Pleistocene have mainly been obtained from lowland sediments, and consequently, there is currently limited information on changes in montane zone vegetation prior to the last glacial stage. However, fossil plant assemblages occurring at high altitudes can be used to assess the influence of climate change on the vertical distribution of plants and vegetation. In this study, we analysed plant macrofossil assemblages from fluvial deposits in the upper Middle Pleistocene strata outcropping in a riverbed at 1160–1180 m a.s.l. in the southeastern foothills of Mt. Yatsugatake, central Japan. Ages of the assemblages were constrained by two widespread tephras that were detected above the interglacial peak of marine isotope stage (MIS) 7.3 (~212 ka). The annual mean temperature in the lower and middle sections of the profile was estimated to be warmer than that at present, based on the coldest temperatures limiting the distribution of Phytolacca japonica and Selaginella remotifolia, and the temperature decreased in the upper section. Since MIS 7.4, the fluctuation in plant altitudinal distribution has been exemplified by changes in the limits of S. remotifolia and Larix kaempferi distribution, and their coexistence at the same altitude varied depending on climate settings. Species diversity, estimated by rarefaction analysis of plant macrofossil assemblage composition, declined as temperatures decreased after the peak of MIS 7.3. Decreasing floral diversity during the subsequent cooling phase possibly coincided with a downward migration of the vegetation zone and extirpation of plants from the inland basin in central Japan.

中文翻译：

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中更新世末期冰川间期温度降低（MIS 7.3）改变了山地带的花艺多样性：来自日本中部的植物化石证据

来自早更新世和中期更新世的植物化石主要来自低地沉积物，因此，在最后冰川期之前有关山地带植被变化的信息目前有限。但是，在高海拔地区发生的化石植物群落可用于评估气候变化对植物和植被垂直分布的影响。在这项研究中，我们分析了位于山东南麓的1160-1180 m asl的河床中上更新世地层露头的河床沉积物中的植物大化石组合。日本中部八岳市。组合的年龄受到两个广泛分布的特非拉的限制，它们在海洋同位素阶段（MIS）7.3（〜212 ka）的冰间峰上方被发现。粳稻和卷柏卷柏，上部温度下降。自MIS 7.4起，植物最高海拔分布的波动已通过变形链球菌和落叶松分布的极限变化来举例说明，并且它们在同一海拔高度的共存性取决于气候设置。通过MIS 7.3峰值后温度降低，通过植物大化石组合物组成的稀疏分析估计的物种多样性下降。在随后的降温阶段，花卉多样性的下降可能与日本中部内陆盆地植被带的向下迁移和植物的灭绝相吻合。