You are here:
Plant growth under salinity and inundation stress: implications for sea-level rise on tidal wetland function
Citation:
Janousek, Chris AND C. Mayo. Plant growth under salinity and inundation stress: implications for sea-level rise on tidal wetland function. Presented at Western Society of Naturalists, November 08 - 11, 2012.
Impact/Purpose:
Coastal sea-level rise may increase estuarine salinity and the duration that estuarine organisms are submerged. We conducted a field experiment with transplanted seedlings and demonstrated that both salinity and inundation reduced plant productivity even for species typically associated with lower elevation, more saline wetlands. Plants grown at typical mid-marsh elevations had higher above and below-ground growth than plants grown 25 to 50 cm below this elevation. Species tolerances to the stressors we manipulated varied, but even species common to lower, more saline marshes declined in productivity. Our results suggest that relative sea-level rise will negatively impact biomass production broadly in estuarine floras with potential impacts on wetland function. Loss of above-ground production may negatively impact food availability for wetland consumers and reductions in below-ground production may reduce accretion potential for marshes vying to keep pace with further sea-level rise.
Description:
Climate change and sea-level rise (SLR) may increase salinity or inundation duration for tidal wetland organisms. To test the effects of these stressors on wetland productivity, we transplanted seedlings of seven common plant species to polyhaline, mesohaline and oligohaline tidal marshes on the Oregon coast. At each site, juvenile plants were grown at local mean higher high water (a typical mid-marsh elevation) and at 25 and 50 cm below MHHW to increase inundation. Plants were harvested after a short growing season to determine above- and below-ground biomass. Shoot and root production declined for all species with increasing inundation. Growth also varied by site, with the lowest rates in the most saline wetland. We combined water-level and salinity measurements at our sites to estimate a salinity exposure index for each treatment. Higher values of the index were correlated with lower productivity for all species and with declines in root versus shoot production. Species tolerances to inundation and salinity stress varied, but even species common to lower, more saline marshes declined in productivity. Our results suggest that relative SLR in Pacific Northwest tidal marshes may reduce above-ground production for consumers and possibly reduce wetland accretion potential because of reduced root growth.