Unravelling the mechanisms for plant survival on gypsum soils: an analysis of the chemical composition of gypsum plants from Turkey

Abstract

Depending on their specificity to gypsum, plants can be classified as gypsophiles (gypsum exclusive) and gypsovags (non-exclusive). The former may further be segregated into wide and narrow gypsophiles, depending on the breadth of their distribution area. Narrow gypsum endemics have a putative similar chemical composition to plants non-exclusive to gypsum (i.e. gypsovags), which may indicate their similar ecological strategy as stress-tolerant plant refugees on gypsum. However, this hypothesis awaits testing in different regions of the world. We compared the chemical composition of four narrow gypsum endemics, one widely distributed gypsophile and six gypsovags from Turkey. Further, we explored the plasticity in chemical composition of Turkish gypsovags growing on high- and low-gypsum content soils. Differences were explored with multivariate analyses (RDA) and mixed models (REML). Narrow gypsum endemics segregated from gypsovags in their chemical composition according to RDAs (mainly due to higher K and ash content in the former). Nevertheless, differences were small and disappeared when different nutrients were analysed individually. All the gypsovags studied accumulated more S and ash when growing on high-gypsum than on low-gypsum soils. Similar to narrow gypsum endemics from other regions of the world, most local gypsum endemics from Turkey show a similar chemical composition to gypsovags. This may indicate a shared ecological strategy as stress-tolerant plants not specifically adapted to gypsum. Nevertheless, the narrow gypsum endemic Gypsophila parva showed a chemical composition typical of gypsum specialists, indicating that various strategies are feasible within narrowly distributed gypsophiles.

Checklist of gypsophilous vascular flora in Italy

“…Both the taxonomical and life form spectra concerning the 31 gypsophytes on the Italian Checklist are largely in agreement with the data recorded in other areas of the Mediterranean Basin for this type of substrates (EIONET 2008, Bolukbasi et al 2016). As far as the most represented families are concerned, the taxonomic spectrum of the strictly gypsophilous flora in Italy is similar.…”

“…Information about plant species included in the checklist was collected: (i) taxonomic rank (Bartolucci et al 2018); (ii) family (Peruzzi 2010); (iii) chorology and (iv) life form (Pignatti 1982); (v) conservation status (Rossi et al 2014); and (vi) functional groups (narrow gypsophiles, wide gypsophiles or gypsovags) according to Bolukbasi et al (2016) and Palacio et al (2007). See Suppl.…”

“…Local evolutionary processes have probably been facilitated by the geographical isolation of outcrops, so that the appearance of several plant species with a narrow distribution have been favoured (Moore et al 2014). This kind of geographic speciation could have been complemented by some selective pressure that might have favoured the survival of certain plant lineages on nutrient-unbalanced, water-limited soils which are unfavourable to the establishment of most plants (Merlo et al 1998, 2001, Bolukbasi et al 2016). …”

Roots point to water sources of Welwitschia mirabilis in a hyperarid desert

“…The high concentrations and wide extent of fine roots in the layer of unconsolidated gypsum at 30‐ to 60‐cm depth were unexpected, as gypsum is hydrophilic and poor in nutrients besides sulphur (Palacio et al, ), creating conditions that few plants can tolerate (Bolukbasi, Kurt, & Palacio, ). Some plants do however succeed in obtaining water when gypsum heats up during the day and releases small amounts of water (Palacio, Azorín, Montserrat‐Martí, & Ferrio, ).…”

“…There is not yet sufficient information to test whether welwitschia is a gypsophile, dependent on gypsum (Drohan & Merkler, 2009), or merely a gypsovag, having the ability to tolerate and make use of the properties of gypsum (Escudero, Palacio, Maestre, & Luzuriaga, 2015). Association with gypsum would reduce competition, as many plant species do not tolerate gypsic conditions (Bolukbasi et al, 2016).…”