DOI: 10.5061/dryad.5hqbzkh3j
title: Nitrogen enrichment stimulates wetland plant responses whereas salt amendments alter sediment microbial communities and biogeochemical responses

description: Freshwater wetlands of the temperate north are exposed to a range of
 pollutants that may alter their function, including nitrogen (N)-rich
 agricultural and urban runoff, seawater intrusion, and road salt
 contamination, though it is largely unknown how these drivers of change
 interact with the vegetation to affect wetland carbon (C) fluxes and
 microbial communities. We implemented a full factorial mesocosm (378.5 L
 tanks) experiment investigating C-related responses to three common
 wetland plants of eastern North America (Phragmites australis, Spartina
 pectinata, Typha latifolia), and four water quality treatments (fresh
 water control, N, road salt, sea salt). During the 2017 growing season, we
 quantified carbon dioxide (CO2) and methane (CH4) fluxes, above- and
 below-ground biomass, root porosity, light penetration, pore water
 chemistry (NH4+, NO3-, SO4-², Cl-, DOC), soil C mineralization, as well as
 sediment microbial communities via 16S rRNA gene sequencing. Relative to
 freshwater controls, N enrichment stimulated plant biomass, which in turn
 increased CO2 uptake and reduced light penetration, especially in Spartina
 stands. Root porosity was not affected by water quality, but was
 positively correlated with CH4 emissions, suggesting that plants can be
 important conduits for CH4 from anoxic sediment to the atmosphere.
 Sediment microbial composition was largely unaffected by N addition,
 whereas salt amendments induced structural shifts, reduced sediment
 community diversity, and reduced C mineralization rates, presumably due to
 osmotic stress. Methane emissions were suppressed by sea salt, but not
 road salt, providing evidence for the additional chemical control (SO4-2
 availability) on this microbial-mediated process. Thus, N may have
 stimulated plant activity while salting treatments preferentially enriched
 specific microbial populations. Together our findings underpin the utility
 of combining plant and microbial responses, and highlight the need for
 more integrative studies to predict the consequences of a changing
 environment on freshwater wetlands.  
description: We conducted a wetland
 mesocosm experiment during the 2016-2017 growing seasons to test how
 traits (i.e., biomass, root porosity) of three common wetland plants
 (<i>Phragmites australis, Spartina pectinata, Typha latifolia,
 </i>hereafter <i>Phragmites, Spartina, Typha</i>,
 respectively) and four water quality treatments (freshwater control, N,
 road salt, sea salt) interact to alter C gas fluxes
 (CO<sub>2</sub>, CH<sub>4</sub>, C mineralization)
 and sediment microbial communities. Raw data associated
 with plant, pore water, and carbon flux responses are provided
 here. All raw sequence datasets are
 available in the NCBI Short Read Archive (SRA) under the BioProject ID
 PRJNA604015. Please see
 associated manuscript for details on data collection.
description: 2017 plant, pore water, and carbon response metrics are in
 associated CSV file titled "Donatoetal_data."  Responses with
 "NA" indicate that no data are available, either due to sample
 processing error or concentrations below the instuments detection limit. A
 brief description of the response metric headers and their associated
 units can be found in the CSV file titled
 "Donatoetal_metadata." Please see associated manuscript for
 details on data collection and analysis.