Macrofauna in a Full-scale Vertical Flow Constructed Wetland during Vegetative Growth Stage

Abstract

In this study, soil macrofauna in the beds of a full-scale vertical flow constructed wetland were investigated to clarify the effects of vegetation on diversity of soil macrofauna. The investigation was conducted in the vegetative growth stage when plant had a great growth vigor. Because deposits were retained on the surface, macrofauna were investigated only the beds of the first stage. The macrofaunal abundance in vegetated beds was higher than in unvegetated beds, suggesting that vegetation increased macrofaunal diversity. This finding shows that the diversity of vegetation-dependent species generates a different level of diversity in the vegetative growth stage. Though the constructed wetland received rich deposits, i.e. food resources, vegetation affected macrofaunal diversity. Earthworms were most abundant in the 0-10 cm layer of vegetated beds, while their abundance peaked in the 10-20 cm layer of unvegetated beds. These findings may show that importantly, vegetation softens rapid changes in the environment (ex. soil temperature), rather than providing food resources for macrofaunal diversity. It was revealed that plant played an important role on macrofaunal diversity even in the constructed wetland where organic matters were constantly provided from wastewater.