A well-managed wood forest, so-called SATOYAMA, could be a better option of maintaining a low carbon society in the temperate Asia. However, in achieving this, it is very crucial to implement forest management activities. This will improve the growth and reduction of the nutrient competitions. The Harvested wood materials generated through forest management when harnessed properly could serve as a source of alternative energy. Therefore the utilization of woody biomass obtained through forest management can play a significant role not only in combating global warming. The objective of this research is to investigate the biodiversity and evaluate the fuel potential of some selected sub-trees and shrubs which are composed a significant part of biomass and are usually targeted in maintenance activities by forest volunteers in secondary pine and oak forests located in Higashi- Hiroshima city, Japan. In order to evaluate the biodiversity at the unmanaged forest the Important Value Index as derived by Curtis and McIntosh (1950) was used. Also in evaluating the fuel potential of some of the selected species, fuel properties such as calorific value, ash contents and water ratio were determined. It was observed that there are more tree species in the unmanaged section with smaller DBH (diameter to breast height) as compared to managed section. This signifies a high level of competitiveness for plant nutrients among tree species in the unmanaged section. Due to highest IVI values among all species, the unmanaged section of the forest is dominated by Eurya japonica. Based on the wood pellet standard by the JIS Z7302-1 to 4 with calorific value between 17.6 and 18.6 MJ/kg, ash contents between 0.5 and 5.0% and water moisture less than 10%, all the species have their ash contents and water moisture content in the JIS Z7302-1 to 4 standards. However, Ilex pedunculosa, Eurya japonica and Pieris japonica have their calorific values in the range specified by the standard. In terms of high calorific and other good fuel properties, I. pedunculosa, E. japonica and P. japonica species are considered the best wood species for fuel pellet production.