Survivorship of a monocarpic bamboo grass, Sasa kurilensis, during the early regeneration process after mass flowering

Abstract

AbstractThe survivorship of a monocarpic bamboo grass, Sasa kurilensis, during the early regeneration process was documented by a 10 year observation of the seedling population after mass flowering in the Hakkoda Mountains, northern Japan. Three phases were recognized: the establishment, density‐stable and thinning phases. The mortality of the densely germinated seedlings (932.9m−2 in a Betula ermanii forest and 1222.3 m−2 in a Sasa grassland) was high, up to 0.5 year−1, in the establishment phase (0–1 year after germination) and low in the density‐stable phase (1–3 years after germination). After reaching full density state, the seedling population showed a nearly constant mortality of 0.18 year−1 due to self‐thinning (the thinning phase). The high C/F ratio presumably caused suppressed seedlings to die. Recovery of the S. kurilensis population was estimated to require ca 20 years in the study plots, judging from the height growth and the decrease in culm density of the seedling population. The illuminance on the ground was higher in the flowered population than in the unflowered one for 5 years after mass death. The duration of high ground illuminance is an important factor affecting the dynamics of forests with Sasa undergrowth, because tree seedlings need to establish under high ground illuminance for the successful regeneration of the forests.