## 3 Results
### Soil Characteristics among the Three Plant Species in HTF  
We observed statistically differences (\(p<0.05\)) in redox potential (Eh) for Bp and Sv compared to Bm in the dry season for both rhizosphere (R) and bulk (B) soils (Figure 3). On the other hand, there were no differences in pH, and total contents of C, N, and S (TOC, TN, and TS) among the soils vegetated by the three halophytic plants (Figure 3). Nutrients contents showed some changes among the different soil-plant systems (Figure 3). NH\({}_{4}^{+}\) contents were higher in BmB (Bm in bulk soil) than BpB and SvB (Bp and Sv in bulk soils); but NO\({}_{3}\)-, available-P, and calcium carbonate equivalent (CCE) did not differ statistically (Figure 3). Regarding the exchangeable cations, we observed higher K\({}^{+}\) and lower Mg\({}^{2+}\) in BmR and BpR when compared to BpR (R for rhizosphere soils of Bm, Bp, and Bp), but higher K\({}^{+}\) in BpB than Bm and SvB (Figure 4). For the soluble cations (Na\({}^{+}\), Ca\({}^{2+}\), Mg\({}^{2+}\), K\({}^{+}\)), the monovalent soluble-K\({}^{+}\) and -Na\({}^{+}\) contents were higher in Sv than Bm and Bp in both rhizosphere (R) and bulk (B) soils, but no differences in the divalent soluble-Mg\({}^{2+}\) and -Ca\({}^{2+}\) and in the values for CEC and ESP (Figure 4).  
Figure 5: Iron (Fe) fractions obtained in sequential extraction for bulk and rhizberic soils in three plant species and two seasons in the hypersaline tidal flat. (F1) Exchangeable and soluble Fe; (F2) Iron associated with carbonate; (F3) Iron associated with poorly crystalline Fe (Ferrihydrite); (F4) Iron associated with poorly crystalline Fe (Lepidoptera); (F5) Iron associated with crystaline oxyhydroxide; (F6) Iron associated with Pyrrite; (DOP) Degree of Pyritization. Plant species are represented by Bm: _Batis maritima_; Bp: _Blutaparon portulacoides_; Sv: _Sporobolus virginicus_. Seasonality represented by d: dry season; w: wet season.  
Figure 6: **(A)** Discriminant analysis (DA) of plant species distribution and soil properties in the hypersaline tidal flat (HTF). **(B)** Discriminant analysis (DA) contrasting rhizosphere and bulk soils properties. **(C)** Discriminant analysis (DA) for rhizosphere and bulk soils properties during dry and wet season. Plant species are represented by Bm: _Batis martiima_; **B**p: _Blutaparon portulacoides_; **Sv: _Sporobolus virginicus_. Soil proprieties are Exch.: exchangeable cations (Na\({}^{+}\) each; K\({}^{+}\) exch; Ca\({}^{2+}\) exch; Mg\({}^{2+}\) exch); Sol.: soluble cations (Na\({}^{+}\) sol; K\({}^{+}\) sol; Ca\({}^{2+}\) sol; Mg\({}^{2+}\) sol); Tot: total (C tot; N tot; S tot); CEC: cations exchangeable capacity; ESP: exchangeable sodium percentage; EC: electrical conductivity; CCE: Calcium Cabonate Equivalent. Iron (Fe) geochemical fractionation, with the following fractions: F1: Exchangeable Fe; F2: Fe bound to Carbonate; F3: ferrihydrite Fe; F4: lepidocrotic Fe; F5: Crystalline Fe; F6: Pyritic Fe; DOP: Degree of Pyriitization.  
The three studied plant species were efficient in altering the soil Fe fractions especially during the dry season (Figure 5). In the dry season, Bp presented the greatest amount of pseudo-total Fe (sum of all Fe fractions), followed by Bm and then Sv, demonstrating a predominance of oxyhydroxides (F3, F4, and F5) because of the drier environment (Figure 5).  
Furthermore, differences in soil characteristics were observed among the three plant species by the discriminant analysis (DA) in the studied HTF (Figure 6A). For instance, the Bp plants are associated with soils containing higher values of exchangeable cations (mainly Ca\({}^{2+}\), Mg\({}^{2+}\), and K\({}^{+}\)) and low-crystallinity Fe-oxyhydroxides (fractions F3 and F4). On the other hand, the Sv are associated with higher salt contents (e.g., EC and soluble cations; Figure 6A). The Bm is associated with sites with higher contents of TOC and TN, and with lower Eb values, when compared to the other plant species (Figure 6A).