Effects of excessive harvest on plant species and forest structures in a subtropical evergreen forest of Castanopsis sieboldii

Abstract

The subtropical evergreen forest of Yanbaru in the northern district of Okinawa is famous for its treasury of biodiversity. For the most part, biodiversity continues to persist in abundance, especially in the forests inside the US Marine base - The Jungle Warfare Training Center (JWTC), which escaped the excessive harvest after WWII. However, these forests also experienced excessive use of trees and shrubs during the war. Now that the return of more than half the JWTC area is close at hand, it is important to clarify the effects of this pre-1945 impact in order to develop a biological conservation plan. Accordingly, plant species and forest structures in evergreen broadleaved forests dominated by Castanopsis sieboldii, the major forest type in Yanbaru, were investigated. The impact of severe use during the war was not detected in species richness and species composition. However, stand volumes and foliage height diversity in forests that were severely used before 1945 were found to be less developed. Rehabilitation of these severely used forests of C. sieboldii is an important mission for biological conservation, because many indigenous animals selectively inhabit old-grown forests of C. sieboldii with highly developed structures.