| dc.description.abstract | - We investigated accumulation of elements (Ca, Co, Cr, Cu, Fe, K, Mg,
Mn, P, Pb, and Zn) in leaves of different ages for 11 evergreen woody plant species
from serpentine soils of New Caledonia. Species were classifi ed into four categories of Ni accumulation ability: one species was a non-accumulator (<100 mg Ni/
kg), three were accumulators (100–1000 mg Ni/kg), two were hyperaccumulators
(1000–10,000 mg Ni/kg), and fi ve were hypernickelophores (>10,000 mg Ni/kg).
We harvested leaves from each species, separating them into three (four in one case)
relative age categories based upon their position along branches (younger toward
the apex, older far from it). Leaf samples were dried, ground, and dry-ashed, and
their elemental concentrations were determined by inductively coupled plasma
spectrometry (all elements except Ni) or atomic absorption spectrophotometry (Ni).
Great variation was found for most elements both within and among species, but
Ni varied most (1050-fold between species for oldest leaves). Correlations between
Ni and other transition metals showed no signifi cant relationships within samples
of any species, but, we found signifi cant positive correlations between Ni and Pb
(correlation coeffi cient = 0.97) and Ni and Fe (correlation coeffi cient = 0.87) among
species. Leaf Ni concentrations varied signifi cantly with leaf age for two species, the
hypernickelophores Geissois pruinosa and Homalium kanaliense. We conclude that
Ni concentration varies markedly between species, but generally does not vary with
leaf age within species. We also suggest that four Ni accumulation category terms—
non-accumulator, hemi-accumulator, hyperaccumulator, and hypernickelophore—be
used to subdivide the wide variation found in Ni concentrations in plant leaves. | en_US |
