Abstract :
[en] Phytostabilisation (i.e. using plants to immobilise contaminants) represents a
well-known technology to hamper heavy metal spread across landscapes. In
Katanga (D. R. Congo), Microchloa altera, a tolerant grass from the copper
hills, was recently identified as a candidate species to stabilise copper in the
soil. More than 50 grasses compose this flora, which may be studied to
implement phytostabilisation strategies. However, little is known about their
phenology, tolerance, reproductive strategy or demography. The present study
aims to characterize the other Poaceae that may be used in phytostabilisation
purposes based on the following criteria: their ecological distribution, seed
production at two times, abundance, soil coverage and the germination
percentage of their seeds. We selected seven perennial Poaceae that occur on the
copper hills. Their ecological distributions (i.e. species response curves) have
been modelled along copper or cobalt gradients with generalized additive
models using logic link based on 172 presence/absence samples on three sites.
For other variables, a total of 69 quadrats (1 m2) were randomly placed across
three sites and habitats. For each species, we compared the number of
inflorescence-bearing stems (IBS) by plot, the percentage of cover, the number
of seeds by IBS and the estimated number of seeds by plot between sites and
habitat. Three species (Andropogon schirensis, Eragrostis racemosa and
Loudetia simplex) were very interesting for phytostabilisation programs. They
produced a large quantity of seeds and had the highest percentage of cover.
However, A. schirensis and L. simplex presented significant variations in the
number of seeds and the percentage of cover according to site.
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