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GCE-LTER Key Findings

 

River flow supports marsh production

Freshwater delivery is an important factor determining estuarine characteristics. Decreases in river discharge associated with droughts influence estuarine salinity and residence time (Y. Wang et al. 2017), and organic matter composition (Medeiros et al. 2015). This connection was borne out by Wieski and Pennings (2014), who examined GCE long-term plot level data on Spartina alterniflora. They found that river discharge was the most important driver of net primary production at almost all GCE sites, with high primary production in years following high river discharge. This is also consistent with trends in satellite-derived estimates of S. alterniflora aboveground biomass, as O'Donnell & Schalles 2016) documented a long-term decline of ~34% in plant biomass that appears to be related to increased frequency of drought (Fig.).

Plant-Herbivore interactions

Patterns in annual biomass of tall (red), medium (blue) and short (green) Spartina, estimated from Landsat5 (solid lines,with dotted regression lines). Slopes of trend lines are -13; -8.5 and -6.5 g/m2/y for tall, medium and short Spartina. Shading indicates drought periods as indicated by the Palmer Drought Severity Index. Modified from O’Donnell & Schalles 2016

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This material is based upon work supported by the National Science Foundation under grants OCE-9982133, OCE-0620959, OCE-1237140 and OCE-1832178. Any opinions, findings, conclusions, or recommendations expressed in the material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.