Effects of plant diversity on substrate organic carbon dynamics in a vertical subsurface flow constructed wetland

This study attempted to measure the contents of substrate organic carbon(SOC) in four different seasons in a full-scale constructed wetland in southeastern China to investigate the effects of plant diversity (i.e., plant species diversity, functional group diversity and plant composition) on seasonal dynamics of SOC. ANOVA analysis in this study showed that plant species diversity had significant effect on SOC in Spring (April, 2008) and Winter (January, 2009), and plant composition had very significant effect, while functional group diversity had no significant effect in the four seasons. Therefore, plant species diversity and composition in general explained much more about the measured nutrient cycling processes (such as SOC) than did functional group diversity in high nutrient supply in the full-scale constructed wetland. Meanwhile, all treatments had the highest SOC pool size in Winter and Spring. While those in Summer (July, 2008) and Autumn (October, 2008) were lower, indicating that the seasonal dynamic rules of SOC were very consistent with plant growth cycle. In addition, in four seasons, soil organic carbon content decreased with the increase of soil bulk density, and plant biomass decreased with the increase of SOC in October, 2008.