Abstract
Summary We investigated the effects of elevated atmospheric CO 2 concentrations (ambient + 200 ppm) on fine root production and soil carbon dynamics in a loblolly pine ( Pinus taeda ) forest subject to free‐air CO 2 enrichment (FACE) near Durham, NC (USA). Live fine root mass (LFR) showed less seasonal variation than dead fine root mass (DFR), which was correlated with seasonal changes in soil moisture and soil temperature. LFR mass increased significantly (by 86%) in the elevated CO 2 treatment, with an increment of 37 g(dry weight) m −2 above the control plots after two years of CO 2 fumigation. There was no long‐term increment in DFR associated with elevated CO 2 , but significant seasonal accumulations of DFR mass occurred during the summer of the second year of fumigation. Overall, root net primary production (RNPP) was not significantly different, but annual carbon inputs were 21.7 gC m −2 y −1 (68%) higher in the elevated CO 2 treatment compared to controls. Specific root respiration was not altered by the CO 2 treatment during most of the year; however, it was significantly higher by 21% and 13% in September 1997 and May 1998, respectively, in elevated CO 2 . We did not find statistically significant differences in the C/N ratio of the root tissue, root decomposition or phosphatase activity in soil and roots associated with the treatment. Our data show that the early response of a loblolly pine forest ecosystem subject to CO 2 enrichment is an increase in its fine root population and a trend towards higher total RNPP after two years of CO 2 fumigation.
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Claims 13
Claim · model-written summary
Live fine root mass varied less seasonally than dead fine root mass.
- Taxon
- Pinus taeda
Pinus taedat0 - Outcome
- Live fine root mass (LFR)e0
- Direction
- less seasonal variatione0
- Comparator
- dead fine root mass (DFR)e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Live fine root mass (LFR) showed less seasonal variation than dead fine root mass (DFR)”
t0“loblolly pine ( Pinus taeda ) forest”
Claim · model-written summary
Dead fine root mass was correlated with seasonal soil moisture and temperature changes.
- Taxon
- Pinus taedaPinus taedat0
- Outcome
- dead fine root mass (DFR)e0
- Qualifier
- seasonal changes in soil moisture and soil temperaturee0
- Setting
- soile0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“dead fine root mass (DFR), which was correlated with seasonal changes in soil moisture and soil temperature”
t0“loblolly pine ( Pinus taeda ) forest”
Claim · model-written summary
Elevated CO2 significantly increased live fine root mass by 86%, or 37 g(dry weight) m −2, after two years.
- Taxon
- Pinus taedaPinus taedat0
- Treatment
- elevated CO 2 treatmente0
- Outcome
- LFR masse0
- Direction
- increasede0
- Value
- 86%e0
- Qualifier
- after two years of CO 2 fumigatione0
- Comparator
- control plotse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“LFR mass increased significantly (by 86%) in the elevated CO 2 treatment, with an increment of 37 g(dry weight) m −2 above the control plots after two years of CO 2 fumigation.”
t0“loblolly pine ( Pinus taeda ) forest”
Claim · model-written summary
Elevated CO2 gave no long-term increment in dead fine root mass.
- Taxon
- Pinus taedaPinus taedat0
- Treatment
- elevated CO 2e0
- Outcome
- DFRe0
- Direction
- no long‐term incremente0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“There was no long‐term increment in DFR associated with elevated CO 2”
t0“loblolly pine ( Pinus taeda ) forest”
Claim · model-written summary
Dead fine root mass accumulated significantly during the second summer of fumigation.
- Taxon
- Pinus taedaPinus taedat0
- Outcome
- DFR masse0
- Direction
- accumulationse0
- Qualifier
- during the summer of the second year of fumigatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“significant seasonal accumulations of DFR mass occurred during the summer of the second year of fumigation”
t0“loblolly pine ( Pinus taeda ) forest”
Claim · model-written summary
Elevated CO2 did not significantly change root net primary production overall.
- Taxon
- Pinus taedaPinus taedae1
- Treatment
- elevated atmospheric CO2t0
- Outcome
- root net primary production (RNPP)e0
- Direction
- not significantly differente0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Overall, root net primary production (RNPP) was not significantly different”
t0“elevated atmospheric CO2 on fine root production and activity in an intact temperate forest ecosystem”
e1“loblolly pine ( Pinus taeda ) forest”
Claim · model-written summary
Elevated CO2 increased annual carbon inputs by 21.7 gC m −2 y −1 (68%) versus controls.
- Taxon
- Pinus taedaPinus taedat0
- Treatment
- elevated CO 2 treatmente0
- Outcome
- annual carbon inputse0
- Direction
- highere0
- Value
- 21.7 gC m −2 y −1 (68%)e0
- Comparator
- controlse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“annual carbon inputs were 21.7 gC m −2 y −1 (68%) higher in the elevated CO 2 treatment compared to controls”
t0“loblolly pine ( Pinus taeda ) forest”
Claim · model-written summary
Specific root respiration was generally unchanged by CO2 treatment during most of the year.
- Taxon
- Pinus taedaPinus taedat0
- Treatment
- CO 2 treatmente0
- Outcome
- Specific root respiratione0
- Direction
- not alterede0
- Qualifier
- during most of the yeare0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Specific root respiration was not altered by the CO 2 treatment during most of the year”
t0“loblolly pine ( Pinus taeda ) forest”
Claim · model-written summary
Specific root respiration was significantly 21% higher in September 1997 under elevated CO2.
- Taxon
- Pinus taedaPinus taedat0
- Treatment
- elevated CO 2e0
- Outcome
- Specific root respiratione1
- Direction
- highere0
- Value
- 21%e0
- Qualifier
- September 1997e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“it was significantly higher by 21% and 13% in September 1997 and May 1998, respectively, in elevated CO 2”
t0“loblolly pine ( Pinus taeda ) forest”
e1“Specific root respiration was not altered by the CO 2 treatment during most of the year”
Claim · model-written summary
Specific root respiration was significantly 13% higher in May 1998 under elevated CO2.
- Taxon
- Pinus taedaPinus taedat0
- Treatment
- elevated CO 2e0
- Outcome
- Specific root respiratione1
- Direction
- highere0
- Value
- 13%e0
- Qualifier
- May 1998e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“it was significantly higher by 21% and 13% in September 1997 and May 1998, respectively, in elevated CO 2”
t0“loblolly pine ( Pinus taeda ) forest”
e1“Specific root respiration was not altered by the CO 2 treatment during most of the year”
Claim · model-written summary
Root tissue C/N ratio did not differ significantly with treatment.
- Taxon
- Pinus taedaPinus taedat0
- Treatment
- the treatmente0
- Outcome
- C/N ratio of the root tissuee0
- Direction
- did not find statistically significant differencese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“We did not find statistically significant differences in the C/N ratio of the root tissue, root decomposition or phosphatase activity in soil and roots associated with the treatment.”
t0“loblolly pine ( Pinus taeda ) forest”
Claim · model-written summary
Root decomposition did not differ significantly with treatment.
- Taxon
- Pinus taedaPinus taedat0
- Treatment
- the treatmente0
- Outcome
- root decompositione0
- Direction
- did not find statistically significant differencese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“We did not find statistically significant differences in the C/N ratio of the root tissue, root decomposition or phosphatase activity in soil and roots associated with the treatment.”
t0“loblolly pine ( Pinus taeda ) forest”
Claim · model-written summary
Soil and root phosphatase activity did not differ significantly with treatment.
- Taxon
- Pinus taedaPinus taedat0
- Treatment
- the treatmente0
- Outcome
- phosphatase activity in soil and rootse0
- Direction
- did not find statistically significant differencese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“We did not find statistically significant differences in the C/N ratio of the root tissue, root decomposition or phosphatase activity in soil and roots associated with the treatment.”
t0“loblolly pine ( Pinus taeda ) forest”
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