Abstract
Colonies of Bazzania trilobata (L.) S. Gray, a common and abundant species on the floor of closed canopy mixed and coniferous forests in New Brunswick, were observed to be pale and dry within a 2-yr-old clear-cut area. This multi-part study used a combination of approaches to assess the species' tolerance of various drying regimes. 1) To determine viability of field-dried shoots, bundles of shoots from the clear-cut and from an adjacent closed canopy forest (controls) were compared in terms of color and net photosynthetic rate (using Infra Red Gas Analysis, IRGA) before and after two months of laboratory “recovery” conditions (light, temperature, and humidity similar to those documented in closed canopy forest). Shoot elongation during recovery was also quantified. Field-dried shoots were viable: following recovery period, they had increased in length, shifted in hue, and displayed positive net photosynthesis, however none of these measures of metabolic activity equaled those of the controls. 2) The moisture content at saturation, determined for reference, was 1296.4% by weight. 3) The drying effect of the IRGA process was evaluated by subjecting moist pre-weighed bundles of shoots to three successive sequences of IRGA, re-weighing, and 24 hr of recovery. IRGA resulted in slight (approximately 40%) moisture loss from shoots initially averaging 368.9% moisture (S.E. = 9.96%), but did not cause a significant decrease in net photosynthesis within this range. 4) Tolerance of drying was tested on freshly collected, forest-acclimated moist shoots. Initial net photosynthesis (by IRGA) and moisture content were determined for replicate bundles of shoots. These were then subjected to drying for 1, 2, 4, 7, and 12 d, while control groups were stored at recovery conditions. Net photosynthesis and moisture content were re-measured after drying, and again after 24 hr of recovery. Moisture content of controls declined by approximately 40% during IRGA, and gradually thereafter in recovery conditions; net carbon gain declined over the course of the study. Moisture content of dried shoots declined by an order of magnitude in all treatments, but returned to near control levels after recovery. However, net photosynthesis dropped to zero with drying, and did not resume after rehydration. In view of the sensitivity of B. trilobata to laboratory drying, and its viability on a 2-yr-old clear-cut, we suggest that a) field conditions are neither as severe nor as prolonged as those tested in the laboratory and b) the colonial form prevents inner shoots from uniform exposure to severe conditions.
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Claims 14
Claim · model-written summary
Field-dried shoots remained viable and elongated during recovery, but did not attain control activity.
- Taxon
- Bazzania trilobata
Bazzania trilobatae1 - Organ / stage
- shootse0
- Outcome
- lengthe0
- Direction
- increasede0
- Comparator
- controlse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Field-dried shoots were viable: following recovery period, they had increased in length, shifted in hue, and displayed positive net photosynthesis, however none of these measures of metabolic activity equaled those of the controls.”
e1“Colonies of Bazzania trilobata (L.) S. Gray”
Claim · model-written summary
Field-dried shoots shifted hue after recovery but did not match controls.
- Taxon
- Bazzania trilobataBazzania trilobatae1
- Outcome
- huee0
- Direction
- shiftede0
- Comparator
- controlse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Field-dried shoots were viable: following recovery period, they had increased in length, shifted in hue, and displayed positive net photosynthesis, however none of these measures of metabolic activity equaled those of the controls.”
e1“Colonies of Bazzania trilobata (L.) S. Gray”
Claim · model-written summary
Field-dried shoots regained positive net photosynthesis after recovery, below controls.
- Taxon
- Bazzania trilobataBazzania trilobatae1
- Outcome
- net photosynthesise0
- Direction
- positivee0
- Comparator
- controlse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Field-dried shoots were viable: following recovery period, they had increased in length, shifted in hue, and displayed positive net photosynthesis, however none of these measures of metabolic activity equaled those of the controls.”
e1“Colonies of Bazzania trilobata (L.) S. Gray”
Claim · model-written summary
Saturated shoots had moisture content of 1296.4% by weight.
- Taxon
- Bazzania trilobataBazzania trilobatae1
- Outcome
- moisture content at saturatione0
- Value
- 1296.4% by weighte0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The moisture content at saturation, determined for reference, was 1296.4% by weight.”
e1“Colonies of Bazzania trilobata (L.) S. Gray”
Claim · model-written summary
IRGA caused about 40% moisture loss from initially moist shoots.
- Taxon
- Bazzania trilobataBazzania trilobatae1
- Treatment
- IRGAe0
- Outcome
- moisture losse0
- Direction
- losse0
- Value
- approximately 40%e0
- Qualifier
- 368.9% moisturee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“IRGA resulted in slight (approximately 40%) moisture loss from shoots initially averaging 368.9% moisture (S.E. = 9.96%)”
e1“Colonies of Bazzania trilobata (L.) S. Gray”
Claim · model-written summary
IRGA did not significantly decrease net photosynthesis at the tested moisture range.
- Taxon
- Bazzania trilobataBazzania trilobatae2
- Treatment
- IRGA processe1
- Outcome
- net photosynthesise0
- Direction
- decreasee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“did not cause a significant decrease in net photosynthesis within this range”
e1“The drying effect of the IRGA process”
e2“Colonies of Bazzania trilobata (L.) S. Gray”
Claim · model-written summary
Control shoot moisture declined about 40% during IRGA and then gradually in recovery.
- Taxon
- Bazzania trilobataBazzania trilobatae1
- Outcome
- Moisture contente0
- Direction
- declinede0
- Value
- approximately 40%e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Moisture content of controls declined by approximately 40% during IRGA, and gradually thereafter in recovery conditions”
e1“Colonies of Bazzania trilobata (L.) S. Gray”
Claim · model-written summary
Control shoot net carbon gain declined over the study.
- Taxon
- Bazzania trilobataBazzania trilobatae1
- Outcome
- net carbon gaine0
- Direction
- declinede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“net carbon gain declined over the course of the study.”
e1“Colonies of Bazzania trilobata (L.) S. Gray”
Claim · model-written summary
Dried shoot moisture content fell an order of magnitude across treatments.
- Taxon
- Bazzania trilobataBazzania trilobatae2
- Treatment
- drying for 1, 2, 4, 7, and 12 de1
- Outcome
- Moisture contente0
- Direction
- declinede0
- Value
- an order of magnitudee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Moisture content of dried shoots declined by an order of magnitude in all treatments”
e1“subjected to drying for 1, 2, 4, 7, and 12 d”
e2“Colonies of Bazzania trilobata (L.) S. Gray”
Claim · model-written summary
Dried shoot moisture returned near control levels after recovery.
- Taxon
- Bazzania trilobataBazzania trilobatae2
- Outcome
- Moisture content of dried shootse1
- Direction
- returnede0
- Comparator
- control levelse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“but returned to near control levels after recovery”
e1“Moisture content of dried shoots”
e2“Colonies of Bazzania trilobata (L.) S. Gray”
Claim · model-written summary
Drying reduced net photosynthesis to zero.
- Taxon
- Bazzania trilobataBazzania trilobatae1
- Treatment
- dryinge0
- Outcome
- net photosynthesise0
- Direction
- droppede0
- Value
- zeroe0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“net photosynthesis dropped to zero with drying”
e1“Colonies of Bazzania trilobata (L.) S. Gray”
Claim · model-written summary
Net photosynthesis did not resume after rehydration.
- Taxon
- Bazzania trilobataBazzania trilobatae2
- Outcome
- net photosynthesise1
- Direction
- did not resumee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“did not resume after rehydration”
e1“net photosynthesis dropped to zero with drying”
e2“Colonies of Bazzania trilobata (L.) S. Gray”
Claim · model-written summary
The authors suggest field drying is less severe or prolonged than laboratory drying.
- Taxon
- B. trilobataBazzania trilobatae1
- Outcome
- field conditions are neither as severe nor as prolongede0
- Qualifier
- those tested in the laboratorye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“field conditions are neither as severe nor as prolonged as those tested in the laboratory”
e1“B. trilobata”
Claim · model-written summary
The authors suggest colony form shields inner shoots from severe exposure.
- Taxon
- B. trilobataBazzania trilobatae1
- Outcome
- prevents inner shoots from uniform exposure to severe conditionse0
- Qualifier
- colonial forme0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the colonial form prevents inner shoots from uniform exposure to severe conditions”
e1“B. trilobata”