Abstract
The marshes of the Louisiana coastline have been deteriorating for decades as plants experience increasing levels of flooding. In this study, we determined the effects of flood duration on four of the most common marsh plants in Louisiana—Spartina alterniflora, Spartina patens, Panicum hemitomon, and Sagittaria lancifolia—by exposing them to different flooding regimes: 0%, 20%, 40%, 60%, 80%, and 100% of the time flooded. Cumulative plant height, soil redox, and soil pH were measured weekly. At the end of the experiment, above- and belowground biomass were measured. Redox measurements showed that the saturated soil (0% flooded) was slightly depleted of oxygen at a redox potential of 300 mV, whereas oxygen was depleted and nitrate and/or manganese used as electron acceptors in all the flooded treatments (20–100% flooded), which had an average soil redox potential near 200 mV. In the saturated treatment, the soil was slightly acidic (pH average 4.7), whereas the flooded treatments had neutral soil acidity (pH average 7.3). Spartina alterniflora biomass was significantly affected by flooding. Spartina alterniflora biomass in the saturated treatment was approximately twice the biomass achieved in any of the flooding treatments. Spartina patens showed a rapid decline in biomass with increased flood duration, reaching the lowest values in treatments that were flooded more than 50% of the time. Although aboveground biomass of Sagittaria lancifolia was not significantly related to flooding regime, belowground biomass decreased with increased flooding duration. The only species that showed no significant response to flooding duration was P. hemitomon. Our results suggest that wetland restoration techniques that reduce flooding frequency are most appropriate for organic marshes dominated by Spartina patens and Spartina alterniflora, whereas these techniques may be less appropriate for organic marshes dominated by Sagittaria lancifolia and P. hemitomon.
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Claims 11
Claim · model-written summary
Saturated soil had redox potential of 300 mV.
Not reportedTaxon
Verbatim
e0“the saturated soil (0% flooded) was slightly depleted of oxygen at a redox potential of 300 mV”
Claim · model-written summary
Flooded soils averaged near 200 mV redox potential.
Not reportedTaxonComparatorDirection
Verbatim
e0“all the flooded treatments (20–100% flooded), which had an average soil redox potential near 200 mV.”
Claim · model-written summary
Saturated soil was slightly acidic at average pH 4.7.
Not reportedTaxon
Verbatim
e0“In the saturated treatment, the soil was slightly acidic (pH average 4.7), whereas the flooded treatments had neutral soil acidity (pH average 7.3).”
Claim · model-written summary
Flooded soil had neutral acidity at average pH 7.3.
Not reportedTaxon
Verbatim
e0“In the saturated treatment, the soil was slightly acidic (pH average 4.7), whereas the flooded treatments had neutral soil acidity (pH average 7.3).”
Claim · model-written summary
Spartina alterniflora biomass in saturated soil was about twice that in flooded treatments.
- Taxon
- Spartina alterniflora
Sporobolus alternifloruse0 - Treatment
- flooding treatmentse0
- Outcome
- biomasse0
- Direction
- twicee0
- Value
- twicee0
- Comparator
- saturated treatmente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Spartina alterniflora biomass in the saturated treatment was approximately twice the biomass achieved in any of the flooding treatments.”
e1“Spartina alterniflora biomass was significantly affected by flooding.”
Claim · model-written summary
Spartina patens biomass declined rapidly with longer flooding, lowest above 50% flooded time.
- Taxon
- Spartina patens
Sporobolus pumiluse0 - Treatment
- increased flood duratione0
- Outcome
- biomasse0
- Direction
- declinee0
- Qualifier
- more than 50% of the timee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Spartina patens showed a rapid decline in biomass with increased flood duration, reaching the lowest values in treatments that were flooded more than 50% of the time.”
Claim · model-written summary
Sagittaria lancifolia aboveground biomass was not significantly related to flooding regime.
- Taxon
- Sagittaria lancifolia
Sagittaria lancifoliae0 - Treatment
- flooding regimee0
- Outcome
- aboveground biomasse0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“aboveground biomass of Sagittaria lancifolia was not significantly related to flooding regime”
Claim · model-written summary
Sagittaria lancifolia belowground biomass decreased with flooding duration.
- Taxon
- Sagittaria lancifoliaSagittaria lancifoliat0
- Treatment
- increased flooding duratione0
- Outcome
- belowground biomasse0
- Direction
- decreasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“belowground biomass decreased with increased flooding duration.”
t0“of Sagittaria lancifolia was not significantly related”
Claim · model-written summary
Panicum hemitomon showed no significant response to flooding duration.
- Taxon
- P. hemitomon
Hymenachne hemitomone0 - Treatment
- flooding duratione0
- Outcome
- response to flooding duratione0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The only species that showed no significant response to flooding duration was P. hemitomon.”
Claim · model-written summary
The authors recommend reducing flooding frequency for organic marshes dominated by Spartina patens and Spartina alterniflora.
- Taxon
- Spartina patensSporobolus pumiluse0
- Outcome
- reduce flooding frequencye0
- Setting
- organic marshese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“wetland restoration techniques that reduce flooding frequency are most appropriate for organic marshes dominated by Spartina patens and Spartina alterniflora”
Claim · model-written summary
The authors consider flood-reduction restoration less appropriate for marshes dominated by Sagittaria lancifolia and P. hemitomon.
- Taxon
- Sagittaria lancifoliaSagittaria lancifoliae0
- Outcome
- less appropriatee0
- Setting
- organic marshese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“these techniques may be less appropriate for organic marshes dominated by Sagittaria lancifolia and P. hemitomon.”
The same questions in other papers
flooding · growth · Sporobolus alterniflorus (smooth cordgrass)Positive and negative results
3 papers in the same direction as this paper · 4 in the opposite direction
- negative
- positive
- positive
4 papers more in this group
See all 8 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.