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Nationwide Yield Prediction by Adding Up Yields of Prefectures

机译：通过地区产量的全国范围内的产量预测

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The purpose of this study was to conduct a yield prediction from 2001 to 2050 on a national level by developing the Gentan probability-based model that combined yields of 47 prefectures. First, the Gentan probabilities were estimated for the 22 prefectures that had reliable harvesting data by the maximum likelihood method. Second, these prefectures were clustered into 3 groups based on the estimated Gentan probability patterns, and then the synthesized Gentan probabilities were estimated for each cluster from the aggregated stand areas and harvested areas of prefectures which belonged to the same cluster. Third, the other 25 prefectures without reliable harvesting data were classified into the preceding 3 clusters by discriminant analysis with socioeconomic explanatory variables. Fourth, harvesting volume were calculated for each prefecture based oh the estimated Gentan probabilities: The former 22 prefectures employed the Gentan probabilities derived from their own harvesting data while the latter25 prefectures employed the synthesized Gentan probabilities corresponding to their cluster number classified. Finally, a yield prediction was conducted from 2001 to 2050 based on the 5 scenarios that increased the means and standard deviations of Gentan probabilities in 47 prefectures by -10%, -5%, 0%, 5% and 10% every 5 years during the prediction periods. The results showed that harvesting areas decreased as the means and standard deviations got raised, and that the scenario of 0% increase brought about moderate result. To actualize this scenario, a standard rotation age in the Regional Management Plan should be raised 5-7% every 5 years for next 50 years.
机译：这项研究的目的是通过建立基于Gentan概率的模型，将47个州的产量相结合，在全国范围内进行2001年至2050年的产量预测。首先，通过最大似然法估算了拥有可靠收成数据的22个县的Gentan概率。其次，根据估计的Gentan概率模式将这些州分为三类，然后根据属于同一群集的州的林分总面积和收获面积，为每个群集估计合成的Gentan概率。第三，通过具有社会经济解释变量的判别分析，将没有可靠收成数据的其他25个县分为前3个区。第四，根据估计的Gentan概率计算每个州的收成量：前22个州使用从自己的收成数据得出的Gentan概率，而后25个州使用与分类簇数相对应的合成Gentan概率。最后，根据5种情况对2001年至2050年的产量进行了预测，这5种情况使47个州的Gentan概率的均值和标准差每5年增加-10％，-5％，0％，5％和10％。预测期。结果表明，随着均值和标准差的增加，收割面积减少，而增加0％的情况带来了中等的结果。为了实现这种情况，在接下来的50年中，应每5年将区域管理计划中的标准轮换年龄提高5-7％。

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