Figure 1.
Illustration of the approach for measuring forest retreat and salt marsh migration.
Forest retreat is the distance between the 2006 forest edge and 1930 forest edge. Salt marsh migration is the proportion of the forest retreat zone that was occupied by salt marsh in 2006. Image from 2006 USDA National Agriculture Imagery Program.
Figure 2.
Relationship between slope and the amount of forest retreat between 1930 and 2006.
Solid line is the predicted value from a Generalized Linear Model with dotted lines representing 95% confidence intervals. See Table 1 for statistical details.
Table 1.
Results of Generalized Linear Model for the effect of slope and salinity on the amount of coastal forest retreat between 1930 and 2006.
Figure 3.
Relationship between location along coast (a proxy for the estuary-wide salinity gradient) and proportion of former forest that became salt marsh between 1930 and 2006.
Solid line is the predicted value from a generalized linear model, with dotted lines representing 95% confidence intervals. See Table 2 for statistical details.
Figure 4.
Relationship between local head of tide (a proxy for local-scale salinity gradients along sub-watersheds) and the proportion of former forest that became salt marsh between 1930 and 2006 after accounting for the interaction between the effect of estuary-wide salinity (see Figure 3).
The relationship is depicted at two example locations to illustrate the effect of the interaction: (A) further away from the mouth of the bay where bay salinity is approximately 18 and (B) depicts this relationship closer to the mouth of the bay in a higher-salinity setting (approximately 28). See table 2 for statistical details.
Table 2.
Results of Generalized Linear Model for the effect of slope and salinity on the amount of marsh migration between 1930 and 2006.