Gross Primary Production of Dwarf Bamboo, Sasa senanensis, in Cool-Temperate Secondary Forests with Different Canopy Structures

Abstract

Secondary forest accounts for almost 60% of the forest area in Japan. Dwarf bamboo (Sasa senanensis) grows widely in the understory of such forest and could make a significant contribution to the overall CO2 sink function (gross primary production, GPP) of forest ecosystems. It is, therefore, necessary to evaluate the GPP of Sasa in various forests and estimate its controlling factors. In this study, we estimated the Sasa GPP at the community level by using a chamber system in an evergreen coniferous forest, a mixed forest, and a deciduous broadleaved forest. We hypothesized that (1) the seasonal trends of Sasa community GPP and Sasa annual GPP would differ in different forest types, (2) in addition to light intensity, the seasonal changes of the Sasa community GPP would be controlled by different factors in the different forest types. As a result, although the seasonal trends of the Sasa GPP and the controlling factors differed among the three forests, the annual Sasa GPP was almost the same for the three forests. This study reveals the possible effect of forest type on the seasonal trends of Sasa GPP and its controlling factors; however, for the annual Sasa GPP, the length of the growing periods would also be an important factor.