Fine‐grained sediment deposition alters the response of plant CSR strategies on the gravel bars of a highly regulated river

Abstract

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Ecological succession and fine sediment accretion influence local patch dynamics of a pioneer riparian species (Typha minimaHoppe)

“…Indeed, regressing boundaries tended to be 0.75 m higher than stable patch boundaries. In riparian habitats, pioneer species may disappear because of continuous bar accretion, which eventually disconnects them from floods and their subsequent habitat rejuvenation (Janssen et al., 2020; Tabacchi et al., 2019). Nevertheless, in the absence of initial‐state data (e.g.…”

“…Once established, the vegetation increases surface roughness, bar flood resistance and favours the accretion of fine sediments, thus accelerating bar aggradation (Corenblit et al., 2009; Gurnell et al., 2012). As the bar rises, the water table disconnection promotes the development of generalist species at the expense of hygrophilous pioneer species (Bertoldi et al., 2011; Corenblit et al., 2009; Janssen et al., 2020). Aggrading bars gradually become less frequently flooded and reworked, and, over decades, herbaceous pioneer species and short‐lived hygrophilous species are gradually replaced by long‐lived species, dominated by young trees (e.g.…”

Optimization of restoration techniques: In-situ transplantation experiment of an endangered clonal plant species (Typha minima Hoppe)

“…Concerning the riparian elevation gradient, we showed that T. minima colonization by clonal expansion was optimal for medium heights above the water level as expected in our second hypothesis. Transplanting at higher levels did not lead to higher T. minima mortality despite a potentially higher competition for resources with later successional species (Janssen et al 2020) or drier abiotic conditions (Shafroth et al 2000). Flood submergence and erosion could explain the survival rate gradient we observed.…”

The taxonomic structure but not the functioning of riparian herbaceous communities varies with hydrological conditions on a large, highly regulated river: Evidence from a 2‐year replicated study

“…This is particularly the case in riparian zones, that is, in the transitional area between terrestrial and aquatic habitats, where plant communities face wide variations in disturbance and stress intensities along the flood gradient (Naiman & Decamps, 1997). These rapid changes in environmental conditions induce a strong turnover in plant strategies, that is, from ruderal‐anoxia‐tolerant species at the bottom of riverbanks to competitive‐desiccation‐tolerant species at the top of riverbanks (Janssen, Piégay, & Evette, 2020; Kyle & Leishman, 2009; McCoy‐Sulentic et al, 2017). River–floodplain connectivity, conceptualized within the flood pulse framework (Junk et al, 1989), is thus a key property of hydrosystems capable of ensuring the functionality and ecological integrity of riparian zones (Naiman & Decamps, 1997).…”