Abstract
Abstract. In the Rhône delta (southern France) Juncus gerardi is a dominant, strongly aggregating species in artificially flooded former rice fields. In order to explain this pattern, the effects of water depth, salinity and their interaction were measured on (1) seed germination and seedling development and (2) vegetative growth of J. gerardi in a controlled‐environment experiment. The germination pattern of J. gerardi was affected by salinity. Low salinity (2 g/l NaCl) delayed germination while moderate salinity (12 g/l NaCl) reduced germination rate. In contrast, the germination of J. gerardi was not affected in the range of water depths tested (i.e. 0–10cm). Salinity negatively affected the development of below‐ground parts, shoots and inflorescences. This negative effect of salinity on the vegetative growth of J. gerardi was amplified when combined with flooding. Flooding with fresh water (0–20 cm depth) did not limit biomass production during the experiment. However, a decrease in the ratio of below‐ground/above‐ground dry weight at deeper water depths suggests a limitation of the vegetative propagation of J. gerardi under prolonged flooding conditions. This hypothesis is supported by the negative correlation between the cover of J. gerardi and water depth found in an abandoned rice field. The limitation on seedling recruitment imposed by salinity and the depression of vegetative growth of J. gerardi due to a combination of salinity and water depth could explain the aggregate distribution of J. gerardi in former rice fields.
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Claims 9
Claim · model-written summary
Low salinity delayed Juncus gerardi germination.
- Taxon
- Juncus gerardi
Juncus gerardiit0 - Treatment
- Low salinity (2 g/l NaCl)e0
- Outcome
- germinatione0
- Direction
- delayede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Juncus gerardi”
e0“Low salinity (2 g/l NaCl) delayed germination”
Claim · model-written summary
Moderate salinity reduced Juncus gerardi germination rate.
- Taxon
- Juncus gerardiJuncus gerardiit0
- Treatment
- moderate salinity (12 g/l NaCl)e0
- Outcome
- germination ratee0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Juncus gerardi”
e0“moderate salinity (12 g/l NaCl) reduced germination rate”
Claim · model-written summary
Water depth from 0 to 10 cm did not affect Juncus gerardi germination.
- Taxon
- J. gerardiJuncus gerardiie0
- Treatment
- water depths tested (i.e. 0–10cm)e0
- Outcome
- germinatione0
- Direction
- not affectede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the germination of J. gerardi was not affected in the range of water depths tested (i.e. 0–10cm).”
Claim · model-written summary
Salinity negatively affected Juncus gerardi below-ground parts, shoots, and inflorescences.
- Taxon
- Juncus gerardiJuncus gerardiit0
- Treatment
- Salinitye0
- Outcome
- development of below‐ground parts, shoots and inflorescencese0
- Direction
- negatively affectede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Juncus gerardi”
e0“Salinity negatively affected the development of below‐ground parts, shoots and inflorescences.”
Claim · model-written summary
Flooding amplified the negative effect of salinity on Juncus gerardi vegetative growth.
- Taxon
- J. gerardiJuncus gerardiie0
- Treatment
- combined with floodinge0
- Outcome
- vegetative growthe0
- Direction
- amplifiede0
- Comparator
- salinitye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This negative effect of salinity on the vegetative growth of J. gerardi was amplified when combined with flooding.”
Claim · model-written summary
Freshwater flooding at 0 to 20 cm did not limit Juncus gerardi biomass production during the experiment.
- Taxon
- Juncus gerardiJuncus gerardiit0
- Treatment
- Flooding with fresh water (0–20 cm depth)e0
- Outcome
- biomass productione0
- Direction
- did not limite0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Juncus gerardi”
e0“Flooding with fresh water (0–20 cm depth) did not limit biomass production during the experiment.”
Claim · model-written summary
Deeper water reduced the below-ground to above-ground dry-weight ratio in Juncus gerardi.
- Taxon
- Juncus gerardiJuncus gerardiit0
- Outcome
- ratio of below‐ground/above‐ground dry weighte0
- Direction
- decreasee0
- Setting
- deeper water depthse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Juncus gerardi”
e0“a decrease in the ratio of below‐ground/above‐ground dry weight at deeper water depths”
Claim · model-written summary
Juncus gerardi cover was negatively correlated with water depth in an abandoned rice field.
- Taxon
- J. gerardiJuncus gerardiie0
- Treatment
- water depthe0
- Outcome
- cover of J. gerardie0
- Direction
- negativee0
- Setting
- an abandoned rice fielde0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“negative correlation between the cover of J. gerardi and water depth found in an abandoned rice field.”
Claim · model-written summary
The authors propose that salinity limits seedling recruitment and, with water depth, suppresses vegetative growth, explaining aggregated Juncus gerardi distribution.
- Taxon
- J. gerardiJuncus gerardiie0
- Outcome
- aggregate distribution of J. gerardie0
- Qualifier
- limitation on seedling recruitment imposed by salinity and the depression of vegetative growthe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The limitation on seedling recruitment imposed by salinity and the depression of vegetative growth of J. gerardi due to a combination of salinity and water depth could explain the aggregate distribution of J. gerardi in former rice fields.”