A new paper by Kazik Wieski and Steve Pennings in Ecosystems shows that Spartina alterniflora production in Georgia increases in years with high discharge from the Altamaha River during the late spring and summer. We examined 12 years of fall biomass data from 9 sites in the GCE-LTER domain, and found that river discharge increased productivity at all the sites, with plant biomass up to 3 times larger in high- versus low-discharge years. Coastal rainfall and year to year variation in sea level also affected plant growth to some extent, but not as consistently as river discharge. It is likely that all three factors affected porewater salinity, and that salinity was the proximate driver of plant production. We also found that hotter summers had lower productivity, because temperatures in GA can exceed the thermal optimum for Spartina alterniflora.
Future work by the GCE-LTER will use LandSat data to extend the S. alterniflora productivity record back in time (O’Donnell and Schalles) and will look at variation in productivity in other common marsh species (Pennings).
Kazimierz Wieski and Steven C. Pennings, 2013, Climate Drivers of Spartina alterniflora Saltmarsh Production in Georgia, USA. Ecosystems. DOI: 10.1007/s10021-013-9732-6.