Abstract
Abstract Net productivity of vegetation is determined by the product of the efficiencies with which it intercepts light ( ɛ i ) and converts that intercepted energy into biomass ( ɛ c ). Elevated carbon dioxide (CO 2 ) increases photosynthesis and leaf area index (LAI) of soybeans and thus may increase ɛ i and ɛ c ; elevated O 3 may have the opposite effect. Knowing if elevated CO 2 and O 3 differentially affect physiological more than structural components of the ecosystem may reveal how these elements of global change will ultimately alter productivity. The effects of elevated CO 2 and O 3 on an intact soybean ecosystem were examined with Soybean Free Air Concentration Enrichment (SoyFACE) technology where large field plots (20‐m diameter) were exposed to elevated CO 2 (∼550 μmol mol −1 ) and elevated O 3 (1.2 × ambient) in a factorial design. Aboveground biomass, LAI and light interception were measured during the growing seasons of 2002, 2003 and 2004 to calculate ɛ i and ɛ c . A 15% increase in yield (averaged over 3 years) under elevated CO 2 was caused primarily by a 12% stimulation in ɛ c , as ɛ i increased by only 3%. Though accelerated canopy senescence under elevated O 3 caused a 3% decrease in ɛ i , the primary effect of O 3 on biomass was through an 11% reduction in ɛ c . When CO 2 and O 3 were elevated in combination, CO 2 partially reduced the negative effects of elevated O 3 . Knowing that changes in productivity in elevated CO 2 and O 3 were influenced strongly by the efficiency of conversion of light energy into energy in plant biomass will aid in optimizing soybean yields in the future. Future modeling efforts that rely on ɛ c for calculating regional and global plant productivity will need to accommodate the effects of global change on this important ecosystem attribute.
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Claims 6
Claim · model-written summary
Elevated CO2 increased soybean yield by 15% over three years.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“A 15% increase in yield (averaged over 3 years) under elevated CO 2”
t0“soybean canopy”
Claim · model-written summary
Elevated CO2 stimulated conversion efficiency by 12%.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“a 12% stimulation in ɛ c”
t0“soybean canopy”
e1“under elevated CO 2 was caused primarily”
Claim · model-written summary
Elevated CO2 increased interception efficiency by 3%.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“ɛ i increased by only 3%”
t0“soybean canopy”
e1“under elevated CO 2 was caused primarily”
Claim · model-written summary
Elevated ozone decreased interception efficiency by 3% through accelerated canopy senescence.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“accelerated canopy senescence under elevated O 3 caused a 3% decrease in ɛ i”
t0“soybean canopy”
Claim · model-written summary
Elevated ozone reduced conversion efficiency by 11%.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“an 11% reduction in ɛ c”
t0“soybean canopy”
e1“the primary effect of O 3 on biomass was through an 11% reduction in ɛ c”
Claim · model-written summary
Elevated CO2 partly mitigated the negative effects of elevated ozone when both were elevated.
- Taxon
- soybean
Glycine maxt0 - Treatment
- CO 2 and O 3 were elevated in combinatione0
- Outcome
- negative effects of elevated O 3e0
- Direction
- partially reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“When CO 2 and O 3 were elevated in combination, CO 2 partially reduced the negative effects of elevated O 3”
t0“soybean canopy”
The same questions in other papers
co2 · yield · Glycine max (soybean)Positive and negative results
85 papers in the same direction as this paper · 10 in the opposite direction
- no effect
- positive
- positive
92 papers more in this group
See all 96 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.