Our laboratory has two permanent survey plots in Tomakomai experimental forest. The one called "Kahan-rin" is secondary forest regrew from artificial clear felling over 50 years ago. The other called "green tunnel" is natural matured forest having grown since over 250 years ago, and this forest had been damaged by a huge typhoon in 2004.
Secondary forest has been taken annual survey from 1998 to 2012, natural forest has been surveyed since 1996 to 2012 every two or tree years. In this study, I picked up some tree species having enough population as main species. I calculated those of density, size-distribution, growth(RGR), entry and mortality in both sites and compared the differences in both sites. The purpose of this study is to figure out how secondary forest has regrown and changed their species composition and size-structure in this 13 years and forecast future form.