Changes in thinning tendencies at a prefectural level caused by direct payments of thinning subsidies
2016
Hiroshima, T. (The University of Tokyo, Seto, Aichi (Japan). Graduate School of Agricultural and Life Sciences, The University of Tokyo Forests, Ecohydrology Research Institute)
The purpose of this paper was to analyze changes of thinning tendencies in the term 2003-2012 based on thinning records summarized by local governments in prefectures, particularly focusing on the years from 2010 to 2012 before and after the new direct payment system of thinning subsidy was enforced. The following three indices were calculated: 1. total thinned area, 2. thinned area or volume with log extraction and 3. ratio of thinned area or volume with log extraction to total thinned area or volume. The average values of indices for the prefectures in 2012, when the direct payment system became widespread, were compared with those from 2003 to 2011. As a result, the index 1 was smallest and the indices 2 and 3 were largest in the term, particularly compared with the values in 2010 when the direct payment system was not enforced yet, the index 1 decreased to 0.726, the 2 and 3 increased to 1.491 and 2.317 respectively. Moreover, the indices 1 and 2 in 2012 became statistically significant as a result of the Steel's multiple tests to the preceding years. These significant changes were considered to be caused by the spread of the direct payment system: The spread brought out both desirable and undesirable aspects of thinning tendencies such as the promotion of log extraction and the regression of stand improvement.
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