Mass Flowering of Dwarf Bamboo Sasa sect. Sasa in Hokkaido in 2022–2023

Abstract

The flowering levels of the dwarf bamboo Sasa sect. Sasa were surveyed along major roads by Integrated Grid Square of Japan (so-called 2nd mesh, 5 min. along latitude, 7 min. 30 s. along longitude, ca. 10 km square) to determine the area of mass flowering in Hokkaido, northern Japan in 2022 and 2023. The levels were classified into five subjective categories. Out of the 975 meshes on the Hokkaido mainland, 176 and 538 were surveyed in 2022 and 2023, respectively. In 6 and 124 meshes surveyed in these years, respectively, more than half of observed Sasa sect. Sasa plants flowered (levels 3 and 4). In 2023, mass flowering was observed in and around the meshes that exhibited flowering in 2022, and the area was divided into western, central, and northern regions by the area where only a few Sasa plants flowered. The lower-level meshes were distributed around areas where multiple level 4 meshes existed. Various morphology of culms with inflorescences were observed, including those exhibiting intermediate characteristics between sect. Sasa and sect. Macrochlamys. Concerns exist in regard to the effects of the increasing sika deer population on Sasa seedling establishment and regeneration dynamics of trees after the mass mortality events.