Abstract
Whole‐tree isoprene emission rates of a chambered white oak were measured throughout the growing season to develop a seasonal emissions model and to compare with emissions estimated using current leaf algorithms and forest canopy models. Emissions increased from mid‐May to a maximum in mid‐July, and the highest rates occurred late in June and throughout July. Rates decreased from early August to mid‐October. A model developed to characterize the whole‐tree emissions accounted for 80% of the variability of observed emissions over the growing season. Peak isoprene emissions and photosynthesis occurred at the same time, but peak emissions continued longer, suggesting that peak photosynthetic rates were not necessary for peak isoprene emissions. Measured light intensities 2 m and 3.3 m down into the tree canopy corresponded to intensities estimated by using current canopy models; however, intensities at l m were 14% lower than predicted by modeling. Measured median leaf‐to‐air temperature differences were 2.0°C at the canopy top and 0.5°C or less in the canopy. Median values of leaf temperatures estimated using a leaf energy balance procedure were slightly lower than air temperatures at all canopy levels, although differences were not more than 0.9°C. The most recently developed biogenic emissions model, which assumes that leaf and air temperatures are the same, predicted July whole‐tree emission rates fairly closely, although high emission rates were slightly underpredicted using the model. Leaf temperature adjustments used in previous canopy models were applied to this model, and in this case, predicted rates underestimated measured rates when measured rates exceeded 80 μg C g −1 h −1 .
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Claims 13
Claim · model-written summary
White oak whole-tree isoprene emissions increased from mid-May to a maximum in mid-July, with highest rates in late June and throughout July.
- Taxon
- white oak
Quercus albat0 - Outcome
- Emissionse0
- Direction
- increasede0
- Qualifier
- mid‐May to a maximum in mid‐Julye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Emissions increased from mid‐May to a maximum in mid‐July”
t0“white oak”
Claim · model-written summary
White oak isoprene emission rates decreased from early August to mid-October.
- Taxon
- white oakQuercus albat0
- Outcome
- Ratese0
- Direction
- decreasede0
- Qualifier
- early August to mid‐Octobere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Rates decreased from early August to mid‐October”
t0“white oak”
Claim · model-written summary
A model developed for whole-tree emissions accounted for 80% of the variability of observed emissions over the growing season.
- Taxon
- white oakQuercus albat0
- Outcome
- variability of observed emissionse0
- Value
- 80%e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“A model developed to characterize the whole‐tree emissions accounted for 80% of the variability of observed emissions over the growing season”
t0“white oak”
Claim · model-written summary
Peak isoprene emissions and photosynthesis occurred at the same time, but peak emissions continued longer.
- Taxon
- white oakQuercus albat0
- Outcome
- Peak isoprene emissions and photosynthesise0
- Direction
- continued longere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Peak isoprene emissions and photosynthesis occurred at the same time, but peak emissions continued longer”
t0“white oak”
Claim · model-written summary
The authors suggest peak photosynthetic rates were not necessary for peak isoprene emissions.
- Taxon
- white oakQuercus albat0
- Outcome
- peak isoprene emissionse0
- Qualifier
- peak photosynthetic rates were not necessarye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“peak photosynthetic rates were not necessary for peak isoprene emissions”
t0“white oak”
Claim · model-written summary
Measured light intensities 2 m and 3.3 m down into the canopy corresponded to intensities estimated by current canopy models.
- Taxon
- white oakQuercus albat0
- Outcome
- light intensitiese0
- Qualifier
- 2 m and 3.3 m down into the tree canopye0
- Comparator
- current canopy modelse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Measured light intensities 2 m and 3.3 m down into the tree canopy corresponded to intensities estimated by using current canopy models”
t0“white oak”
Claim · model-written summary
Light intensities at 1 m in the canopy were 14% lower than predicted by modeling.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“intensities at l m were 14% lower than predicted by modeling”
t0“white oak”
Claim · model-written summary
Measured median leaf-to-air temperature difference was 2.0°C at the canopy top.
- Taxon
- white oakQuercus albat0
- Organ / stage
- canopy tope0
- Outcome
- median leaf‐to‐air temperature differencese0
- Value
- 2.0°Ce0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Measured median leaf‐to‐air temperature differences were 2.0°C at the canopy top and 0.5°C or less in the canopy”
t0“white oak”
Claim · model-written summary
Measured median leaf-to-air temperature difference was 0.5°C or less within the canopy.
- Taxon
- white oakQuercus albat0
- Organ / stage
- the canopye0
- Outcome
- median leaf‐to‐air temperature differencese0
- Value
- 0.5°C or lesse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Measured median leaf‐to‐air temperature differences were 2.0°C at the canopy top and 0.5°C or less in the canopy”
t0“white oak”
Claim · model-written summary
Median leaf temperatures estimated by a leaf energy balance procedure were slightly lower than air temperatures at all canopy levels, by not more than 0.9°C.
- Taxon
- white oakQuercus albat0
- Outcome
- leaf temperaturese0
- Direction
- slightly lowere0
- Value
- not more than 0.9°Ce0
- Comparator
- air temperaturese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Median values of leaf temperatures estimated using a leaf energy balance procedure were slightly lower than air temperatures at all canopy levels, although differences were not more than 0.9°C”
t0“white oak”
Claim · model-written summary
The most recent biogenic emissions model, assuming equal leaf and air temperatures, predicted July whole-tree emission rates fairly closely.
- Taxon
- white oakQuercus albat0
- Outcome
- July whole‐tree emission ratese0
- Value
- fairly closelye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The most recently developed biogenic emissions model, which assumes that leaf and air temperatures are the same, predicted July whole‐tree emission rates fairly closely, although high emission rates were slightly underpredicted using the model”
t0“white oak”
Claim · model-written summary
The same model slightly underpredicted high emission rates.
- Taxon
- white oakQuercus albat0
- Outcome
- high emission ratese0
- Value
- slightly underpredictede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The most recently developed biogenic emissions model, which assumes that leaf and air temperatures are the same, predicted July whole‐tree emission rates fairly closely, although high emission rates were slightly underpredicted using the model”
t0“white oak”
Claim · model-written summary
With previous canopy-model leaf temperature adjustments applied, predicted rates underestimated measured rates when measured rates exceeded 80 μg C g −1 h −1.
- Taxon
- white oakQuercus albat0
- Outcome
- predicted ratese0
- Direction
- underestimatede0
- Value
- 80 μg C g −1 h −1e0
- Comparator
- measured ratese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Leaf temperature adjustments used in previous canopy models were applied to this model, and in this case, predicted rates underestimated measured rates when measured rates exceeded 80 μg C g −1 h −1”
t0“white oak”