A Study Based on the Pollen Analysis of the Formation and Changes of Hinoki (Chamaecyparis obtusa) Forests in Central Japan since the Pleistocene

本研究旨在探讨更新世以来日本中部杉木（Chamaecyparis obtusa）林的形成和变化，为处理杉木造林、森林环境保护和自然环境保护等重要问题提供原始资料。以钻孔收集的12点泥炭为材料，对其进行花粉分析。观察的要点如下：用普通光学显微镜和电子显微镜研究了柏科樟树属（Chamaecyparis）、树属（Thuja）、树属（Thujopsis）和杜松属（Juniperus）的花粉粒、细纹和花粉壁的分层。(1)对长野县Tadachi-Moor泥炭沉积物的分析表明，该地区的天然林分形成于约7000年前，至今仍占主导地位。(2)对长野县Karakemi-Moor泥炭沉积的分析表明，该地区Hinoki自然林分形成于约2.5万年前（末冰期极大期），至今仍以松属为主。(3)对长野县Oahara-Moor泥炭沉积的分析表明，即使在晚极冰期之后，该地区也没有发现天然的Hinoki林分。(4)对富山县南野湖、石岗、池野村、神野寺、Midagahara沼地泥炭沉积的分析表明，即使在冰期后，这些地区也没有发现天然的日野林。从上面可以看出，不同地区的杉木林的形成和变化不是统一的，而是有差异的。

The purpose of the present study is to inquire into the formation and changes of Hinoki (Chamaecyparis obtusa forests in central Japan since the Pleistocene and to get source materials which will help to deal with such important issues as the Hinoki afforestation, the preservation of the forest environment and protection of natural environment. Peat deposits collected by boring at 12 spots were used as the materials, to which the pollen analysis was applied. The outline of the observations is as follows :1. Pollen grains, their fine relief and the stratification of their walls, of four genera - Chamaecyparis, Thuja, Thujopsis and Juniperus belonging to Cupressaceae - have been investigated with an ordinary light microscope and an electron microscope.2. The existence of the following 3 types of Hinoki forests was confirmed by assessing the date of their formation :(1) The analysis of the peat deposits at Tadachi-Moor in Nagano prefecture shows that the natural stand of Hinoki in the area was formed approximately 7,000 years ago and remains predominant to date.(2) The analysis of the peat deposits at Karakemi-Moor in Nagano prefecture shows that the natural stand of Hinoki in the area was formed approximately 25,000 years ago (late glacial maximum) and Pinus maintains predominance to date.(3) The analysis of the peat deposits at Oahara-Moor in Nagano prefecture shows that no natural stand of Hinoki was recognized in the area even after the late glacial maximum.(4) The analysis of the peat deposits at the moor of Nawagaike, Shirokimine, Ikenohira, Kaminokodaira and Midagahara in Toyama prefecture shows that no natural stand of Hinoki was recognized in those areas even after post glacial period.As may be clear from the above, the formation and changes of Hinoki forests is not uniform but diverse in different areas.