Biogeochemical aspects of the serpentines of Rhodes (Greece) and Cyprus

Purpose The sparse ultramafic (serpentine) outcrops of the island of Rhodes, and the much more comprehensive occurrences on Cyprus, have not previously been discussed from a biogeochemical viewpoint. We review the geology and floras of serpentine areas of these two islands, and provide new analytical information about some of the most noteworthy plant species and their soils. Methods Soil and plant samples have been collected from a total of five sites on Rhodes and 11 sites on Cyprus. Standard methods have been used for multielement chemical analysis. Results The plants collected and analysed included all five nickel hyperaccumulating species from Cyprus in the genera Odontarrhena (formerly included in Alyssum) and Noccaea (formerly included in Thlaspi), identified as such in the 1970s from analysis of fragments of herbarium specimens. Their Ni hyperaccumulation is confirmed and their distribution is discussed in relation to the substrate composition. The rare serpentine endemic Alyssum pogonocarpum from Rhodes is not a Ni accumulator. No further instances of Ni hyperaccumulation have been found among the plants collected. For elements other than Ni, plant concentrations of the species collected are generally within the ranges found for serpentine plants in other parts of the world. Conclusion Nickel hyperaccumulation in five species from Cyprus, four in Odontarrhena and one in Noccaea has been confirmed. Within the genus Alyssum as formerly circumscribed, only those species now transferred to Odontarrhena show Ni hyperaccumulation. Conservation issues are important in relation to the rarity of several plant species that are endemic to the ultramafics.

Automated summary

This study evaluates the geology and flora of ultramafic areas on the islands of Rhodes and Cyprus and provides new analytical information about plant species and soils. The study confirms the presence of nickel hyperaccumulating species on Cyprus but not on Rhodes. The concentrations of other elements in the collected plant species are within the ranges observed in ultramafic plants worldwide. The conservation of endemic plant species in ultramafic areas is of great importance.