Nickel availability to Thlaspi caerulescens in an ultramafic toposequence in the Vosges Mountains(France)

摘要

eA serpentinised harzburgite outcrop located in the Vosges Mountains hosts a population of the Ni- hyperaccumulator Thlaspi caerulescens J & C Presl. A complete study was undertaken to relate the variability of Ni availability along the ultramafic toposequence to pedogenesis, soil mineralogy and functionning. The soil profiles ranging from Dystric Cambisol to Hypermagnesic Hypereutric Cambisol, were distributed unevenly along the toposequence probably due to geochemical variability of the bedrock and also complex quaternary erosion features. Ni availability was unexpectedly positively correlated to pH and was controlled by soil mineralogy. In the hypereutric soils, large amounts of Ni were associated with poorly crystallised Fe oxides which were highly available. Ni hyperaccumulation (above 1000mg·kg<'-1>) by native T. caerulescens was only reached in the richest soils as a consequence of the local edaphic factors.