Increased Methane Emissions by an Introduced Phragmites australis Lineage under Global Change

Abstract

North American wetlands have been invaded by an introduced lineage of the common reed, Phragmites australis. Native lineages occur in North America, but many populations have been extirpated by the introduced conspecific lineage. Little is known about how subtle changes in plant lineage may affect methane (CH 4 ) emissions. Native and introduced Phragmites were grown under current and predicted future levels of atmospheric CO 2 and nitrogen(N) pollution in order to understand how CH 4 emissions may vary between conspecific lineages. We found introduced Phragmites emitted more CH 4 than native Phragmites, and that CH 4 emissions increased significantly in both with CO 2 +N treatment. There was no significant difference in CH 4 production potentials, but CH 4 oxidation potentials were higher in soils from the introduced lineage. Intraspecific plant responses to resource availability changed CH 4 emissions, with plant density, root mass, and leaf area being significantly positively correlated with higher emissions. The absence of CO 2 -only or N-only effects highlights a limitation on the generalization that CH 4 emissions are proportional to plant productivity. Our data suggest that intraspecific changes in plant community composition have important implications for greenhouse emissions. Furthermore, global change-enhanced invasion by introduced Phragmites may increase CH 4 emissions unless these factors cause a compensatory increase in carbon sequestration.

Greenhouse Gas Fluxes Vary Between Phragmites Australis and Native Vegetation Zones in Coastal Wetlands Along a Salinity Gradient

“…In a mesocosm experiment, greater CH 4 emissions were attributed to more abundant biomass of invasive relative to native Phragmites (Mozdzer and Megonigal 2013). In our study, however, metrics indicative of Phragmites biomass In the Tukey HSD row, sites not connected by the same letter are significantly different *= Significant at α = 0.05 (stem density and height) did not correlate with CH 4 emissions, suggesting that differences in subsurface soil conditions or belowground biomass may instead be responsible for observed patterns of CH 4 fluxes.…”

“…It may also contribute to decreased CH 4 emissions as a result of rhizosphere methanotrophy, since Phragmites' physiology often leads to a notable oxygenation of its rhizosphere (Armstrong 2000;Colmer 2003). However, invasive Phragmites also has the potential to exacerbate marsh CH 4 emissions relative to native vegetation (Mozdzer and Megonigal 2013). Phragmites' provision of labile organic C to its rhizosphere (Ravit et al 2003;Lovell 2005;Armstrong et al 2006) may result in increased methanogen presence or activity.…”

Temporal and spatial variations of greenhouse gas fluxes from a tidal mangrove wetland in Southeast China

“…The increased CH 4 production can be attributed to both high temperatures (Le Mer and Roger 2001) as well as the activities of aerobic microbes that rapidly consume oxygen causing a decline of redox potentials (Ding et al 2004). Elevated CO 2 levels enhance plant productivity thereby increasing plant biomass production, which in turn further contributes to increased CH 4 emissions (Kao-Kniffin et al 2011;Mozdzer and Megonigal 2013). This suggests that CH 4 emission will keep rising if atmospheric CO 2 concentration continues to rise.…”

Vegetation alters the effects of salinity on greenhouse gas emissions and carbon sequestration in a newly created wetland

“…These would together influence the carbon fluxes. In the globe climate change background, a comprehensive evaluation of carbon absorption and emission is essential to properly assess the climate effects of wetland construction (Poffenbarger et al, 2011;Mozdzer and Megonigal, 2013). However, the effect of salinity on greenhouse gas emissions and carbon sequestration in constructed wetlands has not yet been investigated.…”