Plant Diverisity And Ecosystem Multifunctionality In Constructed Wetlands

The relationship between biodiversity and ecosystem functioning has been one of the research focuses in the field of ecology. Most studies always analyze the effects of biodiversity on a single function or a few functions considered in isolation. Studies have found significant relationships between plant diversity and nitrogen removal, plant biomass production and non-CO2 greenhouse gas emissions in constructed wetlands. However, there has been no research integrating multiple ecosystem functions to study the net effect of plant diversity on the overall functioning (Multifunctionality) in constructed wetlands. Here we conducted two microcosm experiments simulating sand-culture and hydroponic constructed wetlands to study the effect of species richness (1,2,3 and 4) and species identity (absence or presence of particular species) on ecosystem multifunctionality. Both aggregated multifunctionality index (AMF) method and multifunctionality index (MF index) were used to integrate multiple ecosystem functions (CH4 emissions, N2O emissions, plant biomass production, substrate organic carbon sequestration and nitrogen removal) in response to plant diversity. We found that,(1) The net GWP reduction potential indicated by AMF was enhanced by the increasing plant species richness;(2) There had no significantly relationships between the net GWP indicated by MF index and plant species richness.(3) Effect of some key species (Oenanthe javanica or Rumex japonicus) on net GWP could even surpass the effect of plant species richness;(4) Hydroponic systems had a higher GWP reduction potential than sand-culture systems, and it may be due to the homogeneous distribution of nutrient in the hydroponic environment. Per unit plant species richness could create economic benefit of 5590å'Œ 3319 yuan ha-1 yr-1 in sand-culture and hydroponic microcosms, respectively.Our study is the first to integrate multiple ecosystem functions to study the effect of plant diversity on the multifunctionality in constructed wetlands, and broadened the method used in the biodiversity and ecosystem functioning research. In addition, our study could provide theoretical and experimental basis for the optimization of the overall functioning in constructed wetlands.