Gypsum-exclusive plants accumulate more leaf S than non-exclusive species both in and off gypsum

Abstract

Gypsum-exclusive species (gypsophiles), are restricted to gypseous soils in natural environments. However, it is unclear why gypsophiles display greater affinity to gyspeous soils than other soils. These plants are edaphic endemics, growing in alkaline soils with high Ca and S. Gypsophiles tend to show higher foliar Ca and S, lower K and, sometimes, higher Mg than non-exclusive gypsum species, named gypsovags. Our aim was to test if the unique leaf elemental signature of gypsophiles could be the result of special nutritional requirements linked to their specificity to gypseous soils. These nutritional requirements could hamper the completion of their life cycle and growth in other soil types. To test this hypothesis, we cultivated five gypsophiles and five gypsovags dominant in Spanish gypsum outcrops on gypseous and calcareous (non-gypseous) field soil for 29 months. We regularly measured growth and phenology, and differences in leaf traits, final biomass, individual seed mass, seed viability, photosynthetic assimilation and leaf elemental composition. We found all the gypsophiles studied were able to complete their life cycle in non-gypseous soil, producing viable seeds, attaining greater biomass and displaying higher photosynthetic assimilation rates than in gypseous soil. The leaf elemental composition of some species (both gypsophiles and gypsovags) shifted depending on soil, although none of them showed leaf deficiency symptoms. Regardless of soil type, gypsophiles had higher leaf S, Mg, Fe, Al, Na, Mn, Cr and lower K than gypsovags. Consequently, gypsophiles have a unique leaf chemical signature compared to gypsovags of the same family, particularly due to their high leaf S regardless of soil conditions. However, these nutrient requirements are not sufficient to explain why gypsophiles are restricted to gypsum soil in natural conditions.

Plants on Rich-Magnesium Dolomite Barrens: A Global Phenomenon

“…Recent research suggests that knowledge of plant ionome is a key aspect to globally understand the ecosystems of the Earth [ 77 , 78 ]. Much of the research has been focused on this aspect in serpentine plants (e.g., [ 79 , 80 ]) and gypsum (e.g., [ 72 , 81 ]). Attention has been focused on several elements, often considered key, and on their ratios.…”

Do soil features condition seed germination of gypsum plants? An analysis of the effect of different natural soils

“…these distantly related floras. This pattern could ultimately link to a nutritional specialization of gypsophiles to gypseous soils (Cera et al, 2020). Some gypsum endemic species have also been shown to have a higher ability than co-occurring gypsovags to surpass the hard physical crust typical of gypsum soils at the seedling stage (Romão and Escudero, 2005).…”

“…Previous studies have shown how widely distributed gypsophiles from Spain (Palacio et al, 2014, 2007) and the Chihuahuan Desert (Muller et al, 2017) frequently share an ability to accumulate S and Ca in their leaves, which points at a convergent evolution towards similar adaptive traits in plants from these distantly related floras. This pattern could ultimately link to a nutritional specialization of gypsophiles to gypseous soils (Cera et al, 2020). Some gypsum endemic species have also been shown to have a higher ability than co-occurring gypsovags to surpass the hard physical crust typical of gypsum soils at the seedling stage (Romão and Escudero, 2005).…”

Seasonal variation in AMF colonisation, soil and plant nutrient content in gypsum specialist and generalist species growing in P-poor soils

“…Gypsum specialist species differ from generalist species in their foliar S, Ca and Mg concentrations Merlo et al 2019), but not in their leaf P and N (Muller et al 2017;Sánchez-Martín et al 2021). In addition, plants growing on gypseous soils show low foliar P concentrations (Cera et al 2021). Previous studies analysed the differences in AMF colonisation between gypsum specialist and generalist species.…”