Plants response to estuarine constraints: a study of controlled salinity and inundation
Résumé
Estuarine wetlands span a wide array of environmental constraints. As ecosystems at the interface between marine and terrestrial environments, salinity and inundation are among the most important factors impacting growth performances and plant community composition. Vegetation is under high stress in areas where both gradients meet at their high point (close to the river and/or low altitude, resulting in frequent inundations from the tide, and close to the sea, where water salinity is at its highest due to the mixing of fresh water and salt water) and plant communities are shaped by the harsh environmental conditions.
In the current context of climate change, a rise in sea water levels will displace salinity and inundation gradients in estuaries and their associated wetlands. This will significantly change the physical and chemical parameters of the soil types and impact the plant communities within estuarine ecosystems.
We therefore set out to determine the effect of the modification of water salinity and submergence frequency on plant productivity in a pot experiment in controlled conditions. Five individuals of three species (Alopecurus geniculatus, Festuca arundinacea and Holcus lanatus) of estuarine wetlands were exposed to three saltwater concentrations and three inundation frequencies. Growth and biomass production of each individual were assessed non-destructively through photography weekly for 3 months. Leaf traits (SLA, LDMC and chlorophyll content) were also measured during the experiment. We will present the design of this experimental setup, the photography tool developed especially for this study, as well as the results.
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