Greenhouse gas emissions following an invasive plant eradication program

Many efforts have been made to control invasive Spartina alterniflora and to restore coastal wetlands along the Pacific Rim. This study is the first to report the effects of a Spartina-eradication program on soil greenhouse gas (GHG) emissions. In this study S. alterniflora was eradicated in a pilot program covering an area of 0.63 km(2) in a Yangtze River estuarine wetland. In the following year after the eradication program was complete, plant growth, soil microbial activities, as well as CO2, CH4 and N2O emissions were investigated. S. alterniflora ramets did not re-grow after the eradication program, while a native plant, Phragmites australis, thrived and produced taller but rather thinner ramets. CO2, CH4 and N2O emissions in areas previously covered by S. alterniflora declined based on measurements made a year after eradication. This may have been caused by the removal of this plant as well as by flooding and/or by the reduced soil microbial biomass and dehydrogenase and beta-glucosidase activities. CH4 fluxes significantly increased in the program sites where the native species P. australis was retained, while CO2 and N2O fluxes showed no significant changes. Our study revealed that GHG emissions can be greatly altered by an invasive plant eradication program and analysis of such emissions should be included in comprehensive assessments designed to guide successful restoration practices. Based on scenario analysis, we suggest that from the view of GHG emission equivalency, planting P. australis in approximately 50% of the area where S. alterniflora was eradicated would be appropriate in future management. (C) 2014 Elsevier B.V. All rights reserved.