Effects of understory removal on root production, turnover and total belowground carbon allocation in Moso bamboo forests

Abstract

Although the role of roots has been highlighted in carbon and nutrient cycles in forest ecosystems, root production, turnover and total belowground carbon allocation (TBCA) under different management regimes in Moso bamboo forests have not been determined to date. In this study, sequential soil cores were collected at two soil depths (0-20 cm and 20-40 cm) to assess the effects of understory removal on root production, turnover, and TBCA in Moso bamboo forests in subtropical China. A total of 1080 sequential soil cores were collected from April 2011 to March 2012. Understory removal significantly reduced fine root biomass and production for both soil layers (p < 0.05). Total fine root biomass was 781.9, 419.2, and 638.7 g m-2 for an unmanaged stand (stand I), pesticide-treated stand (stand II), and hand-weeded stand (stand III), and fine root production was 467.5, 235.1, and 321.6 g m-2 a-1, respectively. Understory removal did not significantly affect fine root turnover (0.5-0.6 a-1). Fine root turnover showed a strong relationship with fine root production, but not with fine root biomass, indicating that fine root production was the main driver of fine root turnover. TBCA calculated from the component cumulative approach was in order of stand I (481.9 g C m-2 a-1) > stand II (457.7 g C m-2 a-1) > stand III (404.9 g C m-2 a-1), though the differences were not statistically significant (p > 0.05). However, TBCA calculated from the mass balance approach showed a reverse trend compared to the component cumulative approach. The TBCA of stand III was significantly higher than that of stand I and stand II (p < 0.05), demonstrating that the belowground process is complex and standardizing the method of estimation of TBCA is extremely important in global carbon cycle modeling.