*3.3. Validation*

According to the scores obtained, vegetation 1 and 2 classes may represent *Sarcocornia* spp., while vegetation 4 class may correspond to Sporobolus maritimus. Vegetation 3 class has been attributed to areas of overlap of different proportions of these species (i.e., the transition zone).

The categories identified at the field reference points were *Sarcocornia*, *Salicornia*, and transition zones only. However, distinguishing between *Sarcocornia* and *Salicornia* species in the field is very challenging and misidentifications can be expected [76]. The accuracy of the classification was estimated to be 46% but increased to 73% when considering that *Sarcocornia* and *Salicornia* could be mistaken for each other in the field. When comparing the classification to the sets of random pixels, the accuracy ranges from 92 to 96% (Table 2).

**Table 2.** Overall accuracy of the HS image classification. The accuracy is estimated by comparison with field measurements, random samples generated from ROIs, and other groups of random samples (Eq250, Eq500, R10, R20, Sp10, Sp20). Eq250 and Eq500 are the equalized samples groups using 250 and 500 pixels respectively for each class as reference; R10 and R20 are the random samples groups using 10% and 20 % of total pixels as reference respectively; Sp10 and Sp20 are the stratifiedproportionate samples groups using 10% and 20 % of total pixels as reference, respectively.


#### *3.4. Elevation Range of Identified Species*

Vegetation 1 class (identified as a short *Sarcocornia* spp. or a *Salicornia* spp.) is included within the elevation range of the vegetation 2 class (identified as *S. perennis*) (Table 3). The two classes spread across the same elevation range, but the mode of their elevation range is different, with 2.67 m vs 2.79 m for vegetation 1 and 2, respectively. The transitional class (vegetation 3) extended from 1.91 m to 2.78 m, narrowing to 2.26–2.58 m for Q1–Q3. The *S. maritimus* (vegetation 4) covers a range between 1.22 m and 2.35 m (1.76–2.10 m for Q1–Q3). Macroalgae have a bimodal distribution, with two accumulation zones located at 2.49–2.86 m and 3.35–3.84 m (Figure A5).

**Table 3.** Estimated elevation range for each salt marsh vegetation class identified in Cadiz Bay. *S. perennis*: *Sarcocornia perennis*; *S. maritimus*: *Sporobolus maritimus*. Figure A5 shows the frequency distribution of the extracted values for each class; Q: quantile.

