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Potential shifts of natural vegetation in Japan caused by global warming were estimated by the steady-state correlation approach. Two types of vegetation distribution model, the fuzzy model and the multinominal logic model, were applied to explain the relationship between the vegetation classification of remaining natural vegetation and climatic conditions. The logic model resulted in a more successful result than the fuzzy model. Thus, the effects of an increase in mean annual temperature were estimated using the logic model. It was indicated that the percentage of grid-cells in all Japan which showed different estimated vegetation classifications from the present classifications were approximately 23% for a 1 degree increase, 44% for a 2 degree increase, and 62% for a 3 degree increase.Key words: global warming, natural vegetation, potential shift, steady-state correlation approach, vegetation distribution model 1. Introduction Currently, there is concern that global warming might be caused by an increase in greenhouse gases and that the average global temperature might increase approximately 1 degree by the year 2025 and approx. 3 degrees by the end of the next century. Against such a background, research on the impact assessment of global warming and possible countermeasures is being promoted all over the world. This study estimates a potential shift of natural vegetation in Japan under warmed conditions by the so-called "steady-state correlation approach" or "direct transfer function approach" in a series of impact assessment studies.The study develops a vegetation distribution model to explain the relationship between the vegetation classification of remaining natural vegetation and climatic conditions. Estimation was carried out by changing the climatic parameters of the model. Two types of model, the fuzzy model and the linear multinominal logic model, are examined.

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