Host: The Association of Japanese Geographers
1.Introduction
Land use and the condition of natural resources of Amur River watershed has been changed significantly. In Russia, forest resources have been degraded, and in China, rapid paddy field development has been carried out in Sanjiang Plain. We analyzed current state of natural resources and its use, and causes of change. Concerning degradation of forest resources in Russia, we focused ours study to Khabarovsk region, where forest development has been most active in Amur River watershed.
2.Degradation of forest resources in Khabarovsk region and its causes
Changes in forest resource condition in Khabarovsk region could be summarized as degradation. Area covered by forest has been stable, and conversion of forest area to other land use was not significant. Deforestation is not major problem.
On the other hand, condition of forest resources has been significantly changed as follows.(1)Area and volume of coniferous and hard-wooded broadleaved forest with high commercial value has been rapidly decreased.(2)Area of mature and over mature forest has been rapidly decreased.
Major causes for degradation of forest resources are logging activities and forest fire. Most of forest fires were anthropogenic and weak forest management system accelerate damage of fire.
Recently China has rapidly increased timber import from Russia to fill the demand and supply gap. Fundamental forest law of Russia was revised in 2007, and major organizational change in forestry management has been carried out, and forest administration is in confusion. Both issues have negative effect for the conservation of forest.
3.Paddy field development in Sanjiang Plain
In Sanjiang Plan, paddy field development has become active since 1990's. Area of paddy field in 2000 was 1.6million ha, which was eightfold of that of 1980. Increase of domestic demand for rice and relatively good price of rice were the major causes for increase of paddy field development.
Major source for irrigation for paddy field is groundwater. Generally, each farmer dug well and developed irrigation system.
Currently, differentiation of peasantry has almost over and farm management is in stable condition. Major issue of farm management is potential deficit of groundwater. Initial depth of well was 20m, but 30m depth well has become common, and recently 40m depth has become increased to get enough water for irrigation. Paddy field development has negative effect to natural resources in Sanjiang Plain.
