Abstract
summary Red alder ( Alnus rubra Bong.) is a nitrogen‐fixing pioneer tree species of the Pacific Northwest of North America. We investigated the response of different seed sources of red alder to elevated atmospheric CO 2 and to varied levels of water stress. Seeds were stratified, germinated and grown for up to 147 d under ambient (350 //.I I −1 ) or elevated (700 ftl I −1 ) CO 2 . There were no significant interactions of seed source latitude with either treatment, although seedlings from more northerly sources were larger. Elevated CO 2 and low moisture stress resulted in larger plants with more leaf area; effects of the two factors appeared additive. Effects of both factors on biomass allocation, including root: shoot ratios, were small or nonsignificant. Elevated CO 2 decreased specific nitrogenase activity and generally increased photosynthesis ( A ) and stomatal conductance (g). The ratio A: g , potential water use efficiency, also increased when plants were under water stress. Elevated CO 2 appears to improve drought tolerance in red alder. Overall, these results indicate that red alder would benefit in total plant growth from increased ambient CO 2 and could tolerate changes in precipitation.
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Claims 11
Claim · model-written summary
Elevated CO2 gave red alder plants more leaf area and larger size than ambient CO2.
Verbatim
e0“Red alder ( Alnus rubra Bong.)”
e1“Elevated CO 2 and low moisture stress resulted in larger plants with more leaf area”
e2“under ambient (350 //.I I −1 ) or elevated (700 ftl I −1 ) CO 2”
Claim · model-written summary
Low moisture stress gave red alder plants more leaf area and larger size.
Not reportedComparator
Verbatim
e0“Red alder ( Alnus rubra Bong.)”
e1“Elevated CO 2 and low moisture stress resulted in larger plants with more leaf area”
Claim · model-written summary
The effects of elevated CO2 and low moisture stress on red alder appeared additive.
Not reportedDirection
Verbatim
e0“Red alder ( Alnus rubra Bong.)”
e1“Elevated CO 2 and low moisture stress resulted in larger plants with more leaf area”
e3“effects of the two factors appeared additive”
Claim · model-written summary
Red alder seedlings from more northerly seed sources were larger.
Verbatim
e0“Red alder ( Alnus rubra Bong.)”
e4“although seedlings from more northerly sources were larger”
Claim · model-written summary
There were no significant interactions of seed source latitude with the CO2 or water stress treatments in red alder.
Verbatim
e0“Red alder ( Alnus rubra Bong.)”
e5“There were no significant interactions of seed source latitude with either treatment”
Claim · model-written summary
Elevated CO2 decreased specific nitrogenase activity in red alder compared with ambient CO2.
Verbatim
e0“Red alder ( Alnus rubra Bong.)”
e6“Elevated CO 2 decreased specific nitrogenase activity”
e2“under ambient (350 //.I I −1 ) or elevated (700 ftl I −1 ) CO 2”
Claim · model-written summary
Elevated CO2 generally increased photosynthesis and stomatal conductance in red alder compared with ambient CO2.
Verbatim
e0“Red alder ( Alnus rubra Bong.)”
e6“Elevated CO 2 decreased specific nitrogenase activity”
e2“under ambient (350 //.I I −1 ) or elevated (700 ftl I −1 ) CO 2”
e7“generally increased photosynthesis ( A ) and stomatal conductance (g)”
Claim · model-written summary
Potential water use efficiency of red alder increased under water stress.
Not reportedComparator
Verbatim
e0“Red alder ( Alnus rubra Bong.)”
e7“The ratio A: g , potential water use efficiency, also increased when plants were under water stress”
Claim · model-written summary
The two factors had small or nonsignificant effects on biomass allocation, including root:shoot ratios, in red alder.
- Taxon
- Red aldere0
- Treatment
- both factorse6
- Outcome
- biomass allocation, including root: shoot ratiose6
- Direction
- small or nonsignificante6
Not reportedComparator
Verbatim
e0“Red alder ( Alnus rubra Bong.)”
e6“Effects of both factors on biomass allocation, including root: shoot ratios, were small or nonsignificant”
Claim · model-written summary
Elevated CO2 appears to improve drought tolerance in red alder.
Not reportedComparator
Verbatim
e0“Red alder ( Alnus rubra Bong.)”
e7“Elevated CO 2 appears to improve drought tolerance in red alder”
Claim · model-written summary
Increased ambient CO2 would benefit total plant growth of red alder.
Not reportedComparator
Verbatim
e6“Overall, these results indicate that red alder would benefit in total plant growth from increased ambient CO 2”