Dynamic Soil Properties In a Spartina Patens Salt Marsh Subject To Increased Temperature.

Southern New England has a rich land use history that has affected a variety of vegetative communities across the landscape including coastal salt marshes. In many coastal areas tidal wetlands provide a buffer between subtidal coastal ecosystems and adjacent upland areas. This buffer provides numerous ecosystem services including nutrient cycling, wildlife habitat, and pollution control. Anthropogenic impacts to coastal areas such as climate change, development, and tidal alterations could alter many of the processes, and thus ecosystem services provided by salt marshes. The goal of this study was to understand the effect of increased soil and air temperature on soil carbon cycling and storage in coastal salt marshes. Four passive open-top warming chambers were installed and paired with a control plot at a Spartina patens dominated marsh during two growing seasons (2012 and 2013). Process-based carbon flux measurements including soil respiration, above and belowground biomass production, and decomposition were measured in order to quantify soil organic carbon additions and losses during the study period. Samples were collected to determine if warming has a significant effect on dynamic soil properties such as soil salinity, pH, or soil organic carbon content. In 2012, the open-topped warming chambers increased mean soil temperatures ~0.5^oC (p=0.029) and air temperatures ~1.0^oC (p=0.023) above ambient temperatures. During the 2012 season, warmed plots exhibited a 30% increase in aboveground biomass production. Mean soil respiration rates were similar for warmed (1.749 umol CO2 m^-2) and control plots (1.688 umol CO2 m^-2) and no significant difference was observed between decomposition rates. These results could provide more insight on how increased soil and air temperatures may effect carbon processes and storage in southern Rhode Island salt marshes.