Simulations of changing salinity and water level
We conducted two scenarios of increasing salinity (+5 ppt, +10 ppt) and one scenario of decreasing salinity (-5 ppt) to understand how sensitive the model is to changes in average annual salinity. A 5 ppt decrease in salinity (equivalent to 18% decrease relative to average salinity) over the growing season increased GPP by 39%, whereas a 5 ppt increase in salinity lowered GPP by 46% (Fig. 6). A 10 ppt salinity increase (equivalent to a 36% increase relative to average salinity) led to a 80% decrease in GPP relative to the observed salinity. The non-linear shape of the salinity response function dictates that increasing salinity would lead to a lower proportion of change in GPP (Fig. 1). However, increasing salinity also decreased plant height, which makes vegetation more susceptible to flooding effects.
We conducted one scenario in which the mean tide level decreased by 10 cm, and three scenarios in which mean tide level increased by 10 cm, 20 cm, and 50 cm (XX%, XX%, and XX% of mean high tide levels, respectively) (Fig. 7). Lowering the water level by 10 cm resulted in a 2% increase in cumulative GPP. Increasing water level by 10 cm, 20cm, and 50 cm resulted in predicted GPP declining by 2.8%, 6.3%, and 12.4%, respectively. Changing the water level did not substantially change plant height except the scenario of +50 cm water level, which decreased the maximum plant height by 12%.