Data from: Invasive Phragmites increases blue carbon stock and soil volume in a St. Lawrence estuary marsh

2020-02-22T06:43:09Z (GMT) by Jiali Gu Lee vanArdenne Gail Chmura
Our study of a St. Lawrence Estuary marsh reveals that, compared to the native Spartina patens-dominated vegetation, invasive Phragmites australis increases soil volume and carbon stock. The former contributes to marsh resilience to sea level rise and the latter contributes to mitigation of greenhouse gas emissions. Phragmites australis (common reed), is a cosmopolitan species that grows in fresh to brackish wetlands. An invasive genetic strain, introduced from Europe, has expanded extensively along the St. Lawrence River in the last few decades, but has been little studied on the estuarine portion of the St. Lawrence River. We hypothesized that its replacement of native S. patens-dominated salt marsh would alter marsh soil organic carbon stocks (referred to as blue carbon) and accretion rates. To test this hypothesis, we collected soil cores from 3 sites within an invasive Phragmites stand and 1 site within S. patens-dominated stand in a St. Lawrence Estuary salt marsh near la Pocatiere, Quebec. We measured the bulk density, carbon content, volume and mass of belowground organic matter in 2-cm thick soil layers of 3 cores at each site. Results showed that soil in the Phragmites stands held 37-77% more blue carbon than in the S. patens-dominated marsh. Based upon their diameter size, Phragmites rhizomes could be contributing 7.4-10.2 cm of vertical accretion in the upper 20 cm of soil. We suggest that any management of invasive Phragmites include consideration of its role in increasing blue carbon stocks and marsh resilience along with other ecosystem services. This dataset includes relative soil carbon and belowground biomass composition data in a St. Lawrence estuary marsh invaded by Phragmites australis. Data were collected in 3 Phragmites sites in 2019 and 1 Spartina patens site in 2014. There are no data in belowgroud biomass composition in S. patens site. Data were collected to estimate the invasive Phragmites contribution to blue carbon stock and soil volume. This dataset contains one Excel file with two sheets ("main data" and "diameter"). These data are from field samples and lab analysis. Dry bulk density is calculated by dividing the dry weight by the initial volume. The organic matter content of the ground samples was measured through loss on ignition (LOI) with the equation developed by Craft et al. (1991): % organic carbon = 0.40×%LOI + 0.0025(%LOI)2. Rhizomes and roots are sorted (Niering et al. 1977) as much as possible to species and the volume of each species was determined by fluid displacement. The sorted rhizomes and roots were oven dried at 60 °C to constant weight.




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