Natural forests have stable effects on multiple functions, such as water provisioning, increased biodiversity, soil erosion control, and diverse timber production. On the other hand, planted forests left unattended without proper management can prevent sunlight from reaching the forest floor, prevent other plants from regenerating, and destroy the forest ecosystem. Therefore, in order to create highly functional forests, some approaches have begun to convert planted forests into natural forests, however the consequences of this practice in terms of diversity and function are not well understood. In this study, we evaluated the development processes of ecosystem functions and diversity respectively comparing natural regeneration and plantation forest over a 50-year period, following these forestation practices.
 
The study site was in the Teshio Experimental Forest of Hokkaido University in the northern part of Hokkaido, Japan. In Hokkaido, soil-scarification practice is widely conducted to remove dwarf bamboo which prevent seedling from establishment. The Teshio Experimental Forest has been operated for more than 50 years ago and has many natural regeneration and plantation sites with various ages. We conducted both vegetation survey and soil analysis at this site for each treatment and stand age. Following this, we evaluated the recovery rate of each function and compared its similarity to the natural forest over the 50 years after practices were conducted.
 
The results showed that the plantations had higher tree biomass value in all stand ages and was expected to keep an increasing trend even after 50 years. On the other hand, natural regeneration exceeded plantation in the value of litter supply and leaf area index (LAI) almost every age and keep the values around natural forests after 20 years of stand age.  Significant differences in soil multifunctionality were observed between natural and planted forests after 30 years of age. In planted forests, fine root productivity and LAI peaked around 30 years and began to decline, suggesting that available resources were not fully absorbed and unabsorbed nutrients remained in the soil. The multifunctional similarity analysis with natural forests showed that soil functions were different in plantations but tended to be similar to natural forests in natural regeneration. This indicates that soil function recovered faster than vegetation in natural regeneration.