Abstract
Under the Kyoto Protocol, Japan must reduce its emission of greenhouse gases. Thus, it is necessary to increase the amount of forests identified as carbon sinks. This can be achieved through forest management (forests under Article 3.4 of the Kyoto Protocol). This study focuses on thinning, one of silvicultural practices conducted in older planted stands than other practices. We aimed to estimate the rates of thinned areas created for the first time after 1990 (the first thinning) and determine how much forest under Article 3.4 of the Kyoto Protocol was obtained by thinning. The study site consisted of private planted forests in Gifu prefecture. First, we calculated the observed area of the first thinning performed between 1990 and 1994, and between 1995 and 1999 from forest registers and practice records. Second, we calculated the Gentan probabilities based on these observed values subject to the first thinning. We then predicted the first thinning area between 2000 and 2004, and between 2005 and 2009 based on the Gentan probabilities. Finally, employing the observed and predicted values, we estimated the ratio of private planted forests thinned between 1990 and 2009 to all private planted forests assigned to thinning in 1990. The results showed that the ratio was 25%, and that in order to raise this ratio, it is important to promote more thinning in older stands than has previously been performed.
