Rhizomes play significant roles in biomass accumulation, production and carbon turnover in a stand of the tall bamboo <i>Phyllostachys edulis</i>

Abstract

Phyllostachys edulis (Poales: Poaceae) is a bamboo species with well-developed rhizomes, which play important roles in growth, resource storage and transport. However, the extent to which rhizomes are produced, accumulated and turn over annually at the stand level remains largely unknown. We studied the biomass, production and turnover rate of rhizomes and other organs (culms, branches, leaves and roots) in a bamboo stand in Japan between 2013 and 2018. We sought to answer the following questions: To what extent is the newly assimilated carbon allocated to rhizomes, and how rapid is carbon turnover in rhizomes? How does biomass allocation to below-ground parts in bamboo ramets compare to that in woody plant individuals of similar size? We found the amount of newly produced rhizomes was 0.90 Mg C ha–1 year−1, which accounted for 9.5% of total new biomass. The carbon turnover rate of rhizomes was 0.11 g g−1 year−1, which was slower than that of other organs (i.e. longer lifespan). Compared to other woody plants of similar biomass, bamboo had 2.0-fold higher biomass allocation to below-ground organs due to the high biomass of rhizomes. Furthermore, bamboo allocated 8.7-fold lower biomass to leaves despite their high growth rates, perhaps due to the thin (but leathery) leaves and green stems that can photosynthesize as well. Our study highlights that the large storage capacity of below-ground rhizomes along with the efficient above-ground production system are the key growth features of P. edulis, which are likely to contribute to their success in temperate forests.