Abstract
The dwarf bamboo species have been considered important as indicators of forest vegetation type in Japan. On the other hand, dwarf bamboos inhibit the regeneration of tree species. Understanding the distribution dynamics of dwarf bamboo is a major research issue for forest ecology and forest management. Here, we aimed to examine the following questions: 1) whether the dynamics of dwarf bamboo communities can be predicted by ecological characteristics of culm and rhizome? 2) whether the hybrid-origin Sasaella ramosa compete with its parent species, Sasa nipponica? and 3) Does the dominance of Sasa borealis increases toward the S.borealis-dominated climax beech forest? In this study, we investigated the distribution of dwarf bamboos in Ogawa forest reserve for 30 years (1990-2020). The results of the study in 600 quadrats (2 m × 2 m) on a 10 m grid in the 6-ha Ogawa research site showed that the distribution area of Sasa borealis increased from 4.0% to 9.8%, that of Sasa nipponica from 5.0% to 7.3%, and that of Sasaella ramosa from 44.7% to 47.3% of the site. The annual expansion rate was 117, 47 and 53 m2/year for Sasa borealis, Sasa nipponica and Sasaella ramosa, respectively. The estimated life span of culms was 15, 2 and 7 years, respectively. Thus, the dynamics of these three dwarf bamboo species were closely related to their culm's ecological characteristics. The culm height and other characteristics of Sasaella ramosa and Sasa nipponica are similar. It is suggested that the two species will coexist for long time. Sasa borealis having the highest culm height and the longest culm longevity will dominate and the reserve will change to S.borealis - dominated climax forest. One of the large Sasa borealis communities flowered and died in 2017. Its recovery from seedlings will be a new study issue for future research.
