Table 1.
Location and characteristics of study species and sites.
Table 2.
Climatic and edaphic characteristics of study sites.
Table 3.
Frequencies and assignments of the main peaks identified in the analysis of FTIR spectra.
Figure 1.
FTIR spectra of gypsovag species.
The scale of the Y axis is offset for illustration purposes. a) Linum suffruticosum (blue), b) Rosmarinus officinalis (purple), c) Salvia lavandulifolia (green), d) Teucrium polium subsp. capitatum (red), e) Thymelaea tinctoria (pink). Abbreviations of compound peaks: Am: Amide, L: Lignin/Phenolic backbone, Ps: Polysaccharides.
Figure 2.
FTIR spectra of narrow gypsum endemisms.
The scale of the Y axis is offset for illustration purposes. a) Centarurea hyssopifolia (blue), b) Helianthemum marifolium subsp. conquense (red), c) Teucrium pumilum (purple), d) Thymus lacaitae (green). Abbreviations of compound peaks: CH: CH-stretching, Es: Esters.
Figure 3.
FTIR spectra of wide gypsophiles.
The scale of the Y axis is offset for illustration purposes. a) Helianthemum squamatum (purple), b) Lepidium subulatum (red), c) Herniaria fructicosa (green), d) Gypsophyla struthium subsp. hispanica (blue), e) Ononis tridentata (pink). Abbreviations of compound peaks: Gy: Gypsum, Ox: Oxalate.
Table 4.
Results of PLS regression analyses between FTIR spectra and the C (%), N (mg/g), C/N, Na (mg/g), K (mg/g), Ca (%), Mg (mg/g), P (mg/g), S (%) and Ash (%) concentrations of the samples analysed.
Table 5.
Confusion matrix of plant types, based on neural network model prediction.
Figure 4.
Input datasets averaged over each of the gypsum plant types (gypsovags in blue, narrow gypsum endemisms in red, wide gypsophiles in green), for the full wavenumber range.
Figure 5.
Input datasets averaged over each of the plant types (gypsovags in blue, narrow gypsum endemisms in red, wide gypsophiles in green), for the input wavenumber range 1500 to 1900 cm−1.
Figure 6.
Input datasets averaged over each of the plant types (gypsovags in blue, narrow gypsum endemisms in red, wide gypsophiles in green), for the input wavenumber range 1200 to 1400 cm−1.