## 3 Results and Discussion  
### Actual Floristic Inventory of the Different Transitional Systems  
Most of the surveyed systems are dominated by _Halimione portulacoides_, _Spartina maritima_, _Juncus maritimus_, _Sarcocornia fruticosa_, and _Sarcocornia perennis_ (Figure 2). This is a common feature of several transitional systems in Portugal [15]. Nevertheless, Portuguese salt marshes present several plant species ranging from 10 to 15 of approximately 20 possible halophytic species. The high degree of combinations both in terms of the number of species but also of its relative coverage make the different surveyed transitional systems very different in terms of salt marsh communities (Figure 3). Three major transitional system clusters can be observed based on the species coverage data. This grouping pattern reflects the latitudinal differences in the communities along the Portuguese Atlantic coast. In fact, this was already observed in terms of primary productivity and physiology for some species along the Portuguese Atlantic coast [54]. The first cluster comprises the salt marsh communities from the Tagus and Sado estuaries, both located in the central part of the Atlantic coast at very similar latitudes. Both of these systems are dominated by _H. portulacoides_, _S. perennis_, and _S. fruticosa_, covering between 78-80% of the surveyed marshes. A second group can also be observed in the systems dominated by _H. portulacoides_, _S. maritima_, _Scripus maritimus_, and _J. maritimus_, such as the salt marshes from Mondego and Mira estuaries and the Aveiro coastal lagoon. The last cluster is formed by the marsh communities from the Ria Formosa coastal lagoon (the only surveyed system located at the south coast of Portugal) that are dominated by a combination of _S. maritima_, _S. fruticosa_, and _S. perennis_, and with a lower expression of _H. portulacoides_ coverage. These differences in coverage greatly influence not only the present-day value of the ecosystems, but also  
\begin{table}
\begin{tabular}{c c c c c c} \hline  & \multicolumn{5}{c}{**Physiological Impact**} \\ \hline  & **Parameter** & **Minimum** & **Maximum** & **Average** & **Reference** \\ \hline \multicolumn{5}{c}{**Temperature rise**} \\ \hline _A. tripolium_ & \(\alpha\) & & \(-71\%\) & & [45] \\ \hline _H. portulacoides_ & \(\alpha\) & & \(-29\%\) & & [21] \\ \hline _S. maritima_ & \(\alpha\) / \(\mathrm{PP}_{\mathrm{model}}\) & \(-38\%\) & \(10\%\) & \(-14\%\) & [13,19] \\ \hline _S. maritimus_ & \(\mathrm{PP}_{\mathrm{model}}\) & & \(30\%\) & & [19] \\ \hline _Salicorria_ sp. & \(\mathrm{A_{N}}\) & & \(56\%\) & & [46] \\ \hline _Average_ & & \(-71\%\) & \(56\%\) & \(-7\%\) & \\ \hline \multicolumn{5}{c}{**Osmotic stress**} \\ \hline _A. tripolium_ & \(\alpha\) & \(-43\%\) & \(-25\%\) & \(-34\%\) & [22,47] \\ \hline _H. portulacoides_ & \(\mathrm{A_{N}}\)/RGR & \(-75\%\) & \(-50\%\) & \(-63\%\) & [48,49] \\ \hline _S. fruticosa_ & \(\mathrm{A_{N}}\)/RGR & \(-20\%\) & \(47\%\) & \(13\%\) & [49,50] \\ \hline _S. maritima_ & RGR & \(-20\%\) & & [51] \\ \hline _Salicorria_ sp. & \(\mathrm{A_{N}}\) & & \(-38\%\) & & [18] \\ \hline _A. macrostachyum_ & RGR & & \(20\%\) & & [52] \\ \hline _S. perennis_ & Elongation & & \(-67\%\) & & [53] \\ \hline _Average_ & & \(-75\%\) & \(47\%\) & \(-27\%\) & \\ \hline \end{tabular}
\end{table}
Table 4: \(Cont.\)