Plant–soil relationships in the serpentinite screes of Mt. Prinzera (Northern Apennines, Italy)

Abstract

Relations between `bioavailable' metals in serpentinite soils and metal content of plants living on the serpentinite outcrop of Mt. Prinzera (Italy) were investigated. The taxa considered were Alyssum bertolonii Desv., Minuartia laricifolia subsp. ophiolitica (L.) Sch. et Th., Cerastium arvense subsp. suffruticosum (L.) Nym., Biscutella laevigata subsp. prinzerae Raffaelli et Baldoin, Dianthus sylvestris Wulfen group and Silene armeria L. Plants and soils from their rhizospheres were sampled in 1994 and 1995. The soils are enriched in Fe, Al, Cr, Co and Zn as compared to fresh rocks. `Bioavailable' fractions, evaluated by extractions with 0.02 M EDTA and 0.005 M DTPA, show enrichment in Fe, Co and Ni. Metal distribution in plants did not show significant changes between 1994 and 1995, even though different analytical strategies were applied. Our data confirm Alyssum bertolonii as a nickel hyperaccumulator, and the other serpentinophyte Minuartia laricifolia subsp. ophiolitica yielded relatively high metal contents. The determination of nickel distribution between shoots and roots enabled the identification of different strategies of plant adaptation to high Ni concentration in soil: hyperaccumulators, taxa with moderate levels of Ni, taxa with low translocation of Ni, taxa with low metal absorption. These groups can be generalized since the taxa studied all grow on similar soils, and metal availability strongly depends on the degree of weathering of serpentinite. Other metals, such as Cu and Zn, are actively absorbed by plants, both because of relatively high availability in the soil environment and for the active biological role they have.