Supplementary material 1 from: Grewell BJ, Gallego-Tévar B, Castillo JM, Futrell CJ, Drenovsky RE, Harms NE, Pratt PD (2025) Functional trait responses of emergent and free-floating Alternanthera philoxeroides to increasing salinity with sea level rise: stress tolerance, avoidance, and escape strategies. In: Anastácio P, Ribeiro F, Chainho P (Eds) Invasions in Aquatic Systems. NeoBiota 102: 9-36. https://doi.org/10.3897/neobiota.102.150325

Supplementary Material 1 Supplemental tables and figures supporting Functional trait responses of Alternanthera philoxeroides to increasing salinity in tidal wetlands Brenda J. Grewell, Blanca Gallego-Tévar, Jesús M. Castillo, Caryn J. Futrell, Rebecca E. Drenovsky, Nathan E. Harms, Paul D. Pratt Table S1. F-statistic and P-values from General Linear Models with salinity (0.5, 12, 24, 36 ppt) as fixed factor for traits of emergent and free-floating invasive Alternanthera philoxeroides plants. Significant differences are marked in bold. Abbreviation: TNC, total nonstructural carbohydrates. Plant traits Salinity F3,16 P Experiment A: Emergent Growth Form Biomass, morphology and allocation Total biomass (g) 341.530 <0.0001 Specific leaf area (m2 kg-1) 59.509 <0.0001 Leaf mass ratio 1.103 0.377 Adventitious root mass ratio 22.159 <0.0001 Below-ground mass ratio 22.538 <0.0001 Branch intensity index 10.068 <0.0001 Gas exchange and pigments Net photosynthetic rate (µmol CO2 m-2 s-1) 46.228 <0.0001 Water use efficiency (mmol CO2 mol H2O) 44.413 <0.0001 Chlorophyll a (mg g-1) 12.307 <0.0001 Chlorophyll b (mg g-1) 32.885 <0.0001 Carotenoids (mg g-1) 8.722 0.001 Plant tissue bio chemistry Leaf nitrogen (mg g-1) 9.955 <0.0001 Leaf sodium (mg g-1) 64.683 <0.0001 Leaf proline (µmol g-1) 14.471 <0.0001 Leaf glycinebetaine (µmol g-1) 49.189 <0.0001 Leaf total phenolics (mg g-1) 7.156 0.003 Leaf lignin (mg g-1) 8.624 0.001 Stem lignin (mg g-1) 7.466 0.002 Stem node nitrogen (mg g-1) 21.734 <0.0001 Stem node TNC (mg g-1) 0.576 0.639 Soil root TNC (mg g-1) 1.690 0.209 Soil root nitrogen (mg g-1) 9.198 <0.001 Experiment B: Free-floating Growth Form Biomass, morphology and allocation Total biomass (g) 588.930 <0.0001 Specific leaf area (m2 kg-1) 57.292 <0.0001 Leaf mass ratio 150.470 <0.0001 Adventitious root mass ratio 26.206 <0.0001 Stem pith cavity diameter (mm) 40.667 <0.0001 Plant tissue bio chemistry Chlorophyll a (mg g-1) 69.138 <0.0001 Chlorophyll b (mg g-1) 10.462 <0.0001 Leaf nitrogen (mg g-1) 12.692 <0.0001 Leaf proline (µmol g-1) 16.631 <0.0001 Leaf glycinebetaine (µmol g-1) 149.160 <0.0001 Leaf total phenolics (mg g-1) 20.557 <0.0001 Stem node nitrogen (mg g-1) 19.412 <0.0001 Stem node TNC (mg g-1) 8.019 0.001 Figure S1. A priori structural equation model illustrating the hypothesized direct or indirect effects of salinity on three groups of response variables measured in different growth forms of Alternanthera philoxeroides: (1) biomass allocation and morphology, (2) leaf gas exchange and photosynthetic pigments, and (3) plant tissue chemistry. REFERENCES, Fig. S1. Structural Equation Model. 1. Ashraf, M. F. M. R., & Foolad, M. R. (2007). Roles of glycine betaine and proline in improving plant abiotic stress resistance. Environmental and experimental botany, 59(2), 206-216 2. Chaves, M. M., Flexas, J., & Pinheiro, C. (2009). Photosynthesis under drought and salt stress: regulation mechanisms from whole plant to cell. Annals of botany, 103(4), 551-560. 3. Esteban, R., Barrutia, O., Artetxe, U., Fernández-Marín, B., Hernández, A., & García-Plazaola, J. I. (2015). Internal and external factors affecting photosynthetic pigment composition in plants: a meta-analytical approach. 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The evolution of plant functional variation: traits, spectra, and strategies. International Journal of Plant Sciences, 164(S3), S143-S164 15. Tang, L., Zhou, Q. S., Gao, Y., & Li, P. (2022). Biomass allocation in response to salinity and competition in native and invasive species. Ecosphere, 13(1), e3900. 16. Zahra, N., Al Hinai, M. S., Hafeez, M. B., Rehman, A., Wahid, A., Siddique, K. H., & Farooq, M. (2022). Regulation of photosynthesis under salt stress and associated tolerance mechanisms. Plant Physiology and Biochemistry, 178, 55-69. Figure S2. Trait responses to salinity by the emergent growth form of Alternanthera philoxeroides (Experiment A). Different letters above columns indicate significant differences among salinity treatments based on Tukey’s post-hoc tests. Figure S3. Trait responses to salinity by the free-floating growth form of Alternanthera philoxeroides (Experiment B). Different letters above columns indicate significant differences among salinity treatments based on Tukey’s post-hoc tests. Figure S4. Trait responses to salinity by the free-floating growth form of Alternanthera philoxeroides following a freshwater recovery period after exposure to three increasing salinity levels (Experiment C). Different letters above columns indicate significant differences among salinity treatments based on Tukey’s post-hoc tests. Figure S5. Images of Alternanthera philoxeroides (alligator weed; ALPH) invasion in fringing wetlands along oligohaline to mesohaline tidal reaches in Suisun Marsh, San Francisco Bay-Delta Estuary: A) Displacing open water, and native Schoenoplectus actus and Typha domingensis at Wings Landing, Suisun Slough (2023); B) Invading native Schoenoplectus americanus, S. acutus, Euthamia occidentalis, Juncus balticus, and Typha community at Nurse Slough (2024); C) With Schoenoplectus californicus at Grizzly Island, Montezuma Slough (2020); D) Overgrowing T. domingensis – S. acutus along Montezuma Slough (2023); E) Over-growing S. acutus at Chipps Island (2019); F) Displacing Schoenoplectus americanus, Erythranthe guttata, Juncus balticus and Typha sp. at mid-elevation tidal elevation at Montezuma Slough (2024). A B C D E F