Potential of copper-tolerant grasses to implement phytostabilisation strategies on polluted soils in South D. R. Congo: Poaceae candidates for phytostabilisation
2016
Boisson, Sylvain | Le Stradic, Soizig | Collignon, Julien | Seleck, Maxime | Malaisse, François | Shutcha, Mylor Ngoy | Faucon, Michel-Pierre | Mahy, Grégory
Phytostabilisation (i.e. using plants to immobilise contaminants) represents awell-known technology to hamper heavy metal spread across landscapes. InKatanga (D. R. Congo), Microchloa altera, a tolerant grass from the copperhills, was recently identified as a candidate species to stabilise copper in thesoil. More than 50 grasses compose this flora, which may be studied toimplement phytostabilisation strategies. However, little is known about theirphenology, tolerance, reproductive strategy or demography. The present studyaims to characterize the other Poaceae that may be used in phytostabilisationpurposes based on the following criteria: their ecological distribution, seedproduction at two times, abundance, soil coverage and the germinationpercentage of their seeds. We selected seven perennial Poaceae that occur on thecopper hills. Their ecological distributions (i.e. species response curves) havebeen modelled along copper or cobalt gradients with generalized additivemodels 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 acrossthree sites and habitats. For each species, we compared the number ofinflorescence-bearing stems (IBS) by plot, the percentage of cover, the numberof seeds by IBS and the estimated number of seeds by plot between sites andhabitat. Three species (Andropogon schirensis, Eragrostis racemosa andLoudetia simplex) were very interesting for phytostabilisation programs. Theyproduced a large quantity of seeds and had the highest percentage of cover.However, A. schirensis and L. simplex presented significant variations in thenumber of seeds and the percentage of cover according to site.
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