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Acidification et restauration d'écosystèmes forestiers : effets sur les communautés microbiennes et sur des processus fonctionnels associés

Abstract : Many terrestrial and freshwater forested ecosystems are affected by anthropogenic acidification, which can led to deleterious effects on biodiversity and ecosystem functioning. To counteract acidification, liming can be used to improve soil and water physicochemical characteristics in order to restore tree health and headwater stream functioning. In particular, liming has been shown to enhance leaf litter breakdown, which is a key ecosystem process in headwater streams. In this context, the aims of this study were, first to investigate if liming, through its effects on soil chemical characteristics, could induce changes on soil microbial communities, and second to identify what factors could be responsible, at the microbial level, of reduced leaf litter breakdown in acidified headwater streams. Results showed that moderate large-scale liming can induce sustainable changes in soil bacterial communities. Major taxonomic changes revealed notably that the ratio between Proteobacteria and Acidobacteria was higher in limed soils compared to their control counterparts, confirming that this ratio could be a microbial indicator of soil quality improvement. Results obtained in the second part of this work showed that sporulating aquatic hyphomycete diversity on leaves was strongly impaired in acidified streams, whereas fungal diversity investigated by molecular analyses was not depressed. The latter showed a lower proportion of aquatic hyphomycetes and a higher proportion of terrestrial fungi on leaves when exposed in an acidified stream compared to a circumneutral one. Microbial activity analyses bring out that Al may be an important factor that could reduce microbial leaf litter processing, this metal inducing notably a P limitation for microbial decomposers. These effects may in turn have repercussions on higher trophic levels and whole ecosystem functioning
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Submitted on : Thursday, March 29, 2018 - 12:15:14 PM
Last modification on : Friday, April 1, 2022 - 12:48:01 PM
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  • HAL Id : tel-01749398, version 1



Hugues Clivot. Acidification et restauration d'écosystèmes forestiers : effets sur les communautés microbiennes et sur des processus fonctionnels associés. Sciences agricoles. Université de Lorraine, 2012. Français. ⟨NNT : 2012LORR0285⟩. ⟨tel-01749398⟩



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