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Lookup NU author(s): Dr Borbala Hortobagyi
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Pioneer riparian trees such as Populus nigra L. which establish on alluvial bars within dynamic riparian corridors strongly influence fluvial geomorphology by trapping sediments and constructing landforms during floods. The engineering effects (changes in the physical state of the habitat by organisms) of P. nigra on alluvial bars depend on its biomass and its exposure to mechanical stress. P. nigra has a strong phenotypic plasticity that enables individuals to adapt their morphological and biomechanical traits, according to the local hydrogeomorphic conditions. The comprehension and quantification of the variation of morphological and biomechanical response trait attributes of P. nigra populations according to their exposure to mechanical stress is fundamental to better understand why riparian plants are capable to impact fluvial geomorphology. In an empirical in situ study, we quantified the relation between response trait attributes of P. nigra and its exposure to three different levels of mechanical stress. At a highly exposed bar-head, plants clearly developed response traits such as small flexible stems and a strong root system which favour higher mechanical resistance, while at the less exposed bar-tail plants developed taller, less flexible stems and finer root systems. Plants that established in the lower reach of the chute channel developed some common trait attributes in comparison to the bar-tail population and some other trait attributes which were common to the bar-head population. Poplar plants which established on bar-tails favoured bioconstruction, and thus are potentially faster disconnected from hydrogeomorphic disturbances. These results further suggest that fine scale biogeomorphic feedbacks have an influence on larger scale processes within the fluvial corridor requiring hierarchical biogeomorphic bottom-up and top-down cross scale studies for a better understanding of complex biogeomorphic fluvial ecosystems.
Author(s): Hortobágyi B, Corenblit D, Ding Z, Lambs L, Steiger J
Publication type: Article
Publication status: Published
Journal: Géomorphologie: Relief, Processus, Environnement
Year: 2017
Volume: 23
Issue: 3
Pages: 219-231
Print publication date: 30/09/2017
Acceptance date: 01/09/2017
Date deposited: 06/11/2018
ISSN (print): 1266-5304
ISSN (electronic): 1957-777X
Publisher: Groupe français de géomorphologie
URL: https://doi.org/10.4000/geomorphologie.11748
DOI: 10.4000/geomorphologie.11748
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