Sprouting traits of Japanese aspen in an annually burned grassland at the foot of Mt. Sanbe, Shimane Prefecture

Abstract

Sprouting plays an important role in the succession of woody plants in fire-managed grasslands. In this study, we investigated the sprouting traits of Japanese aspen (Populus tremula var. sieboldii) in an annually burned grassland at the foot of Mt. Sanbe in Shimane Prefecture, Japan. We established a 2 m×2 m study plot and surveyed the distribution of roots, root sprouts, and sprouts from burned stems and rootstocks within the plot. The longest root per individual was＞10 m long and included 12 rootstocks. The horizontal roots were mainly found at a depth of ca. 1 cm below the soil surface, and current root sprouts were generated from ca. 3 mm diameter roots. Rootstocks with many large stems arising from sprouts generated in the previous year produced many current-year sprouts. Dead rootstocks tended to have thicker roots than living rootstocks. Highly productive rootstocks appeared to have survived annual burning of the aboveground plant parts. The results indicate that in this grassland, P. tremula var. sieboldii persists despite annual burning via regrowth through sprouting, and expands its distribution through new root sprouts generated from thin, elongating horizontal roots.