Niche construction by the invasive Asian knotweeds (species complex <Emphasis Type="Italic">Fallopia</Emphasis>): impact on activity,abundance and community structure of denitrifiers and nitrifiers |
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Authors: | Nicolas Dassonville Nadine Guillaumaud Florence Piola Pierre Meerts Franck Poly |
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Institution: | 1.Laboratoire d’écologie végétale et biogéochimie,Université Libre de Bruxelles,Brussels,Belgium;2.Université Lyon 1,Villeurbanne,France;3.CNRS, UMR5557, USC 1193 INRA, Laboratoire d’Ecologie microbienne,Villeurbanne,France;4.CNRS, UMR5023, Laboratoire d’Ecologie des Hydrosystèmes fluviaux,Villeurbanne,France |
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Abstract: | Big Asian knotweeds (Fallopia spp.) are among the most invasive plant species in north-western Europe. We suggest that their success is partially explained
by biological and chemical niche construction. In this paper, we explored the microbial mechanisms by which the plant modifies
the nitrogen cycle. We found that Fallopia
spp. decreased potential denitrification enzyme activity (DEA) by reducing soil moisture and reducing denitrifying bacteria density
in the soil. The plant also reduced potential ammonia and nitrite oxydizing bacteria enzyme activities (respectively, AOEA
and NOEA) in sites with high AOEA and NOEA in uninvaded situation. Modification of AOEA and NOEA were not correlated to modifications
of the density of implicated bacteria. AOB and Nitrobacter-like NOB community genetic structures were significantly different in respectively two and three of the four tested sites
while the genetic structure of denitrifying bacteria was not affected by invasion in none of the tested sites. Modification
of nitrification and denitrification functioning in invaded soils could lead to reduced nitrogen loss from the ecosystem through
nitrate leaching or volatilization of nitrous oxides and dinitrogen and could be considered as a niche construction mechanism
of Fallopia. |
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