Vegetation history in Ohsado Mountains at Sado Island

在大佐山，柳杉林分布在海拔约700米以上的粘性土壤上，空气湿度和土壤湿度都很高。在森林中形成湿铁灰壤或干灰壤。而苦柏（Thujopsis dolabrata var.本田林分布在海拔700米以下的相对桑迪和干燥的土壤上，空气湿度较低。在森林中形成了干燥的轻度火山灰土壤。山毛榉林分布在天山高海拔地区。Kinpoku，空气湿度介于前两种森林类型之间。高海拔类型的棕色森林土壤在森林中形成。在柳杉与落叶树种混交林中，在山西省阳山西坡设置大面积调查样地，研究了3种林型的土壤灰化程度和上层土壤化学性质。在Bunagahira，测量了所有树木的位置、大小和树冠结构，包括死亡或砍伐的树桩。蒙古栎柳杉伐桩附近生长有大齿木。以前，几个树种，如柳杉或槭mono被砍伐的人的利益在奥萨多山。因此，现在的森林结构受到过去人类活动的严重影响。其中之一是由柳杉组成的森林遗址，大约200或250年前，杜鹃花科灌木和蕨类植物占主导地位。通过对Kuninaka平原的采样，揭示了近1500年来的植被变化。

In Ohsado Mountains, Cryptomeria japonica forests distributed upper than ca.700m on clayy soil materials, where air humidity and soil moisture were very high. Wet iron podzols or Dry podzols were formed at the forests. Whereas, Thujopsis dolabrata var. hondae forests distributed lower than ca.700m on relativery sandy and dry soil materials, where air humidity was rather low. Dry slightly pozolic soils were formed at the forests. Fagus crenata forests distributed at high altitudes of Mt. Kinpoku, where air humidity was intermediate between former two forest types. High altitude types of Brown forest soils were formed at the forests. The degree of podzolization and soil chemical properties of upper horizons showed clear differences among these three forest types.In the mixed forest consisted of Cryptomeria japonica and deciduous tree species, large-sized investigation plot was set up on the west slope of Mt. Bunagahira, where location, sizes and crown structure of all trees including dead or cut stumps were measured. Quercus mongolica var. grosseserrata grew near the cut stumps of Cryptomeria japonica. Formely, several tree species such as Cryptomeria japonica or Acer mono were cut down for the man's benefit in Osado Mountains. Therefore, present forest structure was storongly affected by past man's activities.Pollen analysis was carried out using samples collected from three different sites in Ohsado regions. One of them was a forested site consisted of Cryptomeria japonica, where Ericaceae shrubs and ferns dominated about 200 or 250 years ago. From the sample collected at Kuninaka Plain, vegetation changes of last 1500 years were showed.