Using minirhizotrons to estimate fine root turnover rate as a forest ecosystem health indicator in Moso bamboo forests in Dagang mountain

摘要

The contribution of fine roots to forest ecosystem health (FEH) is still poorly understood, although fine roots are recognized to provide benefits to ecosystems. To address the relationship between fine roots and forest health, minirhizotrons was used to observe fine root (2mm) dynamics during a 1-year period in nine Moso bamboo [Phyllostachys pubescens Mazel ex J. Houz.] plots having three levels of forest health (health, general health, and sub-health) 6 months after minirhizotron installation in the Dagang mountains (China). Forest health status was assessed by an improved Costanza model in 2011, 3 years after the great 2008 Chinese ice storm. Fine root number, length, and turnover in health plots were significantly higher than those in general health and sub-health plots, indicating that fine root number, length, and turnover rate were positively correlated with forest health condition. On the contrary, fine root diameter increased from 0.39 +/- 0.03 to 0.52 +/- 0.04mm as forest health decreased, suggesting a strong negative correlation between fine root diameter and forest health condition. Fine root turnover rate ranged from 0.68 +/- 0.19 to 1.37 +/- 0.32year(-1) as forest health condition increased. All trees in the nine plots showed a unimodal peak of fine root production with distinct seasonality. The fine root number growth rate peaked in mid-summer and declined over the remainder of the growing season. Thus, fine root of Moso bamboo appear highly sensitive to forest health status, and this study concluded that fine root turnover rate of the minirhizotron tube surface can be used as an indicator to assess FEH in Dagang mountain.