Natural environments of Baiinxile,Xilinhot,Inner Mongolia (Report of the field study under the Monbusho International Scientific Research Program)

摘要

The area belongs to south-eastern part of Haixi fold belt in Innermongolia with outcrop of callys of carboniferous and permian period limestone and sandstone. There were fluctuation movement and taphrogeny at Neozoic Era by which some subsided basins were formed. During the period of Himalayan movement, there were volcanism forming the basalt lava platforms. The altitude of the eastern part is 1300-1500m being higher than the western (less than 1000m). That caused a certian degree of vertical changes in soil and vegetation. Climatically, it belongs to mid-temperate zone, semiarid region with continental temperate steppe climate but moistened by southeast Monsoon in summer. Yearly averaged temperature is -0.4℃. The growing period of steppe plants is 150-180 days. The yearly precipitation is 320-400mm decreasing gradually from east to west. The zonal soil is the chestnut. There are some differentiation in regions and types according to vegetation and local water-het conditions connected with topography in eastern part with higher altitude more than 1250m on the low mountain, hill and basalt platform with vegetation of meadow steppe, dominanted by Slipa baicalensis, Filifolium sibiricum, Carex pediformis and Aneurolepidium chinense, the black earth is developed, in the middle part, above 1150m with typical steppe dominanted by Aneurolepidium chinense and Slipa grandis, there comes dark chestnut. While in western part with lower altitude less than 1000m, it comes to be chestnut dominanted by Slipa krylovii and Artemisia frigida. Besides, there are some extrazonal soils concerning with local topography and water condition, e.g. meadow soil, awamp soil, solonchak and soil. On the sand soil some woodland and shrub are existed.