Litter chemistry prevails over litter consumers in mediating effects of past steel industry activities on leaf litter decomposition.
Soil pollution has adverse effects on the performance and life history traits of microorganisms, plants, and animals, yet evidence indicates that even the most polluted sites can support structurally-complex and dynamic ecosystems. The present study aims at determining whether and how litter decomposition, one of the most important soil ecological processes leaf, is affected in a highly trace-metal polluted site. We postulated that past steel mill activities resulting in soil pollution and associated changes in soil characteristics would influence the rate of litter decomposition through two non-exclusive pathways: altered litter chemistry and responses of decomposers to lethal and sub-lethal toxic stress. We carried out a litter-bag experiment using Populus tremula L. leaf litter collected at, and allowed to decompose in, a trace metal polluted site and in three unpolluted sites used as controls. We designed a fully-factorial transplant experimental design to assess effects of litter origin and exposure site on the rate of litter decomposition. We further determined initial litter chemistry, fungal biomass, mesofauna abundance in litter bags, and the soil macrofauna community. Irrespective of the site of litter exposure, litter originating from the polluted site had a two-fold faster decomposition than litter from the unpolluted sites. Litter chemistry, notably the lignin content, seemed most important in explaining the degradation rate of the leaf litter. Abundance of meso and macro-detritivores was higher at the polluted site than at the unpolluted sites. However, litter decomposition proceeded at similar rates in polluted and unpolluted sites. Our results show that trace metal pollution and associated soil and litter changes do not necessarily weaken consumer control on litter decomposition through lethal and sub-lethal toxic stress.
Laboratoire interdisciplinaire des environnements continentaux, CNRS UMR 7360, Université de Lorraine, 8, rue du général Delestraint, 57070 Metz, France.
Pierre
P
Lucisine
Laboratoire écologie fonctionnelle et environnement, CNRS UMR 5245, Université Toulouse III, 118, route de Narbonne, 31062 Toulouse, France.
Antoine
A
Lecerf
Laboratoire interdisciplinaire des environnements continentaux, CNRS UMR 7360, Université de Lorraine, 8, rue du général Delestraint, 57070 Metz, France.
Michaël
M
Danger
Laboratoire interdisciplinaire des environnements continentaux, CNRS UMR 7360, Université de Lorraine, 8, rue du général Delestraint, 57070 Metz, France.
Vincent
V
Felten
Laboratoire interdisciplinaire des environnements continentaux, CNRS UMR 7360, Université de Lorraine, 8, rue du général Delestraint, 57070 Metz, France.
Delphine
D
Aran
Laboratoire Sols et Environnement, INRA UMR 1120, Université ́de Lorraine, 2, avenue de la Forêt de Haye, 54505, Vandœuvre-lès-Nancy, France.
Apolline
A
Auclerc
Laboratoire interdisciplinaire des environnements continentaux, CNRS UMR 7360, Université de Lorraine, 8, rue du général Delestraint, 57070 Metz, France.
Elisabeth M
EM
Gross
Laboratoire Sols et Environnement, INRA UMR 1120, Université ́de Lorraine, 2, avenue de la Forêt de Haye, 54505, Vandœuvre-lès-Nancy, France.
Hermine
H
Huot
Laboratoire Sols et Environnement, INRA UMR 1120, Université ́de Lorraine, 2, avenue de la Forêt de Haye, 54505, Vandœuvre-lès-Nancy, France.
Jean-Louis
JL
Morel
Laboratoire interdisciplinaire des environnements continentaux, CNRS UMR 7360, Université de Lorraine, 8, rue du général Delestraint, 57070 Metz, France.
Serge
S
Muller
Centre d'Ecologie Fonctionnelle et Evolutive (CEFE), CNRS - Université de Montpellier - Université Paul Valéry Montpellier - EPHE, Montpellier Cedex 5, France.
Johanne
J
Nahmani
Laboratoire interdisciplinaire des environnements continentaux, CNRS UMR 7360, Université de Lorraine, 8, rue du général Delestraint, 57070 Metz, France. Electronic address: florence.maunoury-danger@univ-lorraine.fr.
Florence
F
Maunoury-Danger
D000818:Animals; D004784:Environmental Monitoring; D007448:Invertebrates; D018515:Plant Leaves / Q000737:chemistry*; D012987:Soil / Q000737:chemistry*; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000032:analysis*
D012987:Soil; D012989:Soil Pollutants
Leaf characteristics; Leaf litter decomposition; Litter bags; Soil biota communities; Soil functioning; Trace metals