Skip to Main content Skip to Navigation
Theses

De la complexité fonctionnelle et écophysiologique des ressources lumières, azote et eau dans le réseau précoce d'interactions entre le jeune chêne (Quercus petraea) et deux Poacées (D. cespitosa et M. caerulea) : conséquences pour la régénération des chênaies tempérées

Abstract : Temperate forest ecosystems are prone to regeneration failures because of strong competition between understorey species and tree seedlings. This thesis aimed to improve our understanding of sessile oak seedlings (Quercus petraea) and poacea responses, both in competition among different levels of resource availabilities. Two poacea species were studied, Molinia caerulea and Deschampisa cespitosa. We focused on the role of the different resource combinations (light, water and inorganic nitrogen) on interaction variation (intensity and importance) between those species and underlying ecophysiological mechanisms. Our greenhouse and field experiments allowed us to infer a very early competition, from the first months of interaction between oak seedlings and poacea neighbours. High light level leads to stronger competition from poacea on oak seedlings, increased by nitrogen supply. Secondly nature and extent of these interactions depend on applied abiotic stress level and on considered organs. Thirdly Oak seedlings mainly respond by accumulating resources in coarse roots. These resources are remobilized next year and may have a positive carry-over effect on oak functioning if there is no water stress. Eventually we observed facilitation as well, from oak on D. cespitosa in fertilized environment. Nitrogen supply would foster oak seedling growth, increasing exudate production and root turn-over, to the benefit of D . cespitosa. The poacea would take up this extra nitrogen source for its own development. This study support the idea of including interaction effects of different abiotic factors in competition models. Silvicultural practices would also be enhanced by optimizing species coexistence in temperate forests as soon as tree seedlings and understorey species start to grow together.
Complete list of metadatas

https://tel.archives-ouvertes.fr/tel-01818094
Contributor : Abes Star :  Contact
Submitted on : Monday, June 18, 2018 - 4:42:14 PM
Last modification on : Monday, October 19, 2020 - 10:58:17 AM
Long-term archiving on: : Tuesday, September 25, 2018 - 8:14:54 PM

File

2017CLFAC081-VERNAY.pdf
Version validated by the jury (STAR)

Identifiers

  • HAL Id : tel-01818094, version 1

Collections

Citation

Antoine Vernay. De la complexité fonctionnelle et écophysiologique des ressources lumières, azote et eau dans le réseau précoce d'interactions entre le jeune chêne (Quercus petraea) et deux Poacées (D. cespitosa et M. caerulea) : conséquences pour la régénération des chênaies tempérées. Ecologie, Environnement. Université Clermont Auvergne, 2017. Français. ⟨NNT : 2017CLFAC081⟩. ⟨tel-01818094⟩

Share

Metrics

Record views

379

Files downloads

474