Surface pollen investigation in the warm-temperate to subtropical regions of Japan : an attempt for quantitative palaeoclimate reconstruction on Quaternary interglacials

基于花粉的现代模拟技术(MAT)可以通过重建第四纪晚期人类聚居区的定量古温度来为未来几十年的气候预测(IPCC等)提供约束。然而，所谓的&gt；16℃系统中重建温度的淡出问题阻碍了MAT为比现在更温暖的&gt；2℃世界提供类似的东西。为了减少这一问题，我们对年平均气温超过16℃的日本暖温带至亚热带地区进行了地表花粉调查。在地理背景上，23℃以下的炎热地区选择了基伊半岛南部、四国西南部、九州以及谷儿岛、大岛、冲绳、八条岛等岛屿。采集的样品(由活苔藓组成的表面花粉材料)按照标准的孢粉学程序进行分析，以填补日本&gt；16℃制度的空白。结果提供了一个完整的温度曲线，不缺少极端温度…在孢粉学背景下，几乎所有位于四国岛以南的暖温带至亚热带地区都以丰富的甜锥花粉为主。常绿栎树(青冈)的高值仅限于暖温带上部(年平均气温16℃)。此外，还对琵琶湖化石孢粉记录进行了古气候恢复的尝试。这些结果已被总结成两篇发表在国际期刊上的英文手稿(Okuda等人，Tarasov等人)。我们注意到，该项目还涉及日本群岛周围洋底的表层花粉调查。西北太平洋有很多大洋取心点。由于来自海洋领域的岩心材料保存在JAMSTEC、San-So-Ken等地，因此从岩心顶部采样和分析泥质沉积物可以提供海洋下的表层花粉数据集，其方式与陆地区域的相同。不幸的是，表层花粉样本本身无法在目前东京湾周围的城市地区采集。为了减少这个问题，我们在千叶市中心进行了一个井芯项目。结果表明，距今1500~2500年的化石花粉，受早期人类植被干扰较小，可作为现代地表花粉的替代品。较少

The pollen-based modern analogue technique (MAT) can provide constraints for climate projections for the next decades (IPCC, etc) by reconstructing quantitative palaeotemperature of human habitation areas during the late Quaternary. However, a so-called fade-out problem of reconstructed temperature in >16℃ regime has prevented the MAT from providing analogues for the >2℃ warmer world than present. To reduce this problem, we perform surface pollen investigation for warm-temperate to subtropical regions of Japan, of which annual mean temperature exceeds 16℃.In geographical context, southern Kii peninsula, SW Shikoku, Kyusyu and islands of Tanega-shima, Amami-Oshima, Okinawa, Hachijo-jima, etc are selected for hot region up to 23℃. The collected samples (surface pollen materials composed of living moss polster) are analyzed in the standard palynological procedure to fill the gaps in the >16℃ regime of Japan. Results provide a complete temperature curve without lack in extreme temperature … More zones (5-7℃ warmer than the present in the Kinki-Kanto districts).In palynological context, almost all the lower warm-temperate to subtropical zones, located to the south of Shikoku, are dominated by abundant Castanopsis pollen. High values of evergreen oak (Cyclobalanopsis) are restricted in the upper warm-temperate zone (<16℃ in annual mean temperature). In addition, an attempt of palaeoclimate reconstruction using previous surface pollen is also performed on the fossil pollen record from Lake Biwa. These results have been summarized into two English manuscripts for international journals (Okuda et al., Tarasov et al.).We note that this project also deal with the surface pollen investigation for ocean floors around the Japanese archipelago. The NW Pacific has had a lot of ocean coring points. Since the cored materials from the marine realm are preserved in JAMSTEC, San-So-Ken, etc, sabsampling and analyzing muddy sediments from the core tops can provide surface pollen dataset beneath the ocean, which is in the same manner as those in terrestrial regions.Unfortunately, surface pollen samples themselves cannot be collected in current urban areas around e.g. the Tokyo Bay. To reduce this problem, we performed a borehole core project in central Chiba city. Results show that fossil pollen of 1500-2500 yr BP age, with little vegetation disturbance by early humans, can serve as a substitute for modern surface pollen. Less