Skip to Main content Skip to Navigation
Theses

Conséquences de l'assemblage des communautés végétales sur la décomposition de leur litière

Abstract : During its assembly, a plant community will be strongly modified: immigration of new plant species with new traits, disappearance of particular species with other traits, immigration of new plant-associated organisms (insects, fungi…), trait changes in existing species… All these changes are likely to drive the decomposition of litter produced by the plant community. Litter decomposition is indeed controlled by plant traits, activity of decomposer community, and adaptation of decomposer organisms to plant traits. However, the consequences of plant-community assembly on plant litter decomposition remain entirely unknown. This thesis aims at determining the consequences of plant-community assembly on plant litter decomposition, at distinct scales. First of all, we studied, locally, the consequences of neighboring plants on litter decomposition of plant individuals (i.e. intraspecific scale). We distinguished the case where litter of plant individuals was alone from the case where litter of plant individuals was mixed with litter from other species. Then we studied, more globally, the consequences of plant-community assembly on decomposition at the scale of the entire plant community (i.e. interspecific scale). Finally, we investigated whether plant litter decomposition feedbacks on plant-community assembly. We used two experimental approaches, the first one using a long-term mesocosm experiment for manipulating the local plant neighborhood of plant individuals, and the second one using of Long Term Ecological Research network involving grasslands with different time for assembly. At the local scale, our results indicate that plant individuals grown in functionally dissimilar neighborhood produce a more decomposable litter, and can also harbor more efficient decomposers. When the litter of these individuals is mixed with litter from other species, the decomposition of the litter mixture is accelerated by synergistic effects when neighboring plants are phylogenetically diverse, and functionnally dissimilar to the litter mixture. At the scale of whole plant community, our results show that numerous trait changes occur during assembly (leaf C:N ratio, leaf dry matter content…), as well as changes in the composition of the decomposer community (soil microbial C:N ratio). These changes strongly affect litter decomposition but offset each other, maintaining litter decomposition constant. Finally, our result show that the faster the decomposition of mixed-litter from two species is, the more both species coexist. This thesis demonstrates the major influence of plant-community assembly on plant litter decomposition in grassland ecosystems, from the scale of plant individuals to the scale of entire plant community. Plant-community assembly hence affects after-life ecosystem processes like litter decomposition. This influence occurs through plant traits and decomposer activity. In turn, litter decomposition feedbacks on plant-community assembly. Consequently, litter decomposition does not seem to be a collateral consequence of plant traits, but rather an important part of their ecological strategies and biotic interactions, participating to a feedback loop involving community assembly processes.
Document type :
Theses
Complete list of metadatas

Cited literature [282 references]  Display  Hide  Download

https://tel.archives-ouvertes.fr/tel-01805013
Contributor : Abes Star :  Contact
Submitted on : Friday, June 1, 2018 - 12:42:06 PM
Last modification on : Wednesday, September 9, 2020 - 4:53:27 AM
Long-term archiving on: : Sunday, September 2, 2018 - 1:30:38 PM

File

BARBE_Lou.pdf
Version validated by the jury (STAR)

Identifiers

  • HAL Id : tel-01805013, version 1

Citation

Lou Barbe. Conséquences de l'assemblage des communautés végétales sur la décomposition de leur litière. Biologie végétale. Université Rennes 1, 2017. Français. ⟨NNT : 2017REN1B040⟩. ⟨tel-01805013⟩

Share

Metrics

Record views

140

Files downloads

336