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Effects of elevated atmospheric CO2 concentrations, clipping regimen and differential day/night atmospheric warming on tissue nitrogen concentrations of a perennial pasture grass.

Volder A, Gifford RM, Evans JR - AoB Plants (2015)

Bottom Line: Both warming treatments increased leaf N concentrations under ambient CO2 concentrations, but did not significantly alter leaf N concentrations under elevated CO2 concentrations.Nitrogen resorption from leaves was decreased under elevated CO2 conditions as well as by more frequent clipping.Overall, the effects of CO2, warming and clipping treatments on aboveground tissue N concentrations were much greater than on belowground tissue.

View Article: PubMed Central - PubMed

Affiliation: Department of Plant Sciences, University of California - Davis, Davis, CA, USA avolder@ucdavis.edu.

No MeSH data available.


(A) Effect of clipping frequency and atmospheric CO2 concentration on N resorption efficiency. (B) Effect of warming treatment on N resorption efficiency, Amb = ambient, HN = +2.2 °C/+4.0 °C day/night warming, CW = +3.0 °C continuous warming. Different letters indicate statistically significant differences at P < 0.05 using Student's t LSD test.
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PLV094F5: (A) Effect of clipping frequency and atmospheric CO2 concentration on N resorption efficiency. (B) Effect of warming treatment on N resorption efficiency, Amb = ambient, HN = +2.2 °C/+4.0 °C day/night warming, CW = +3.0 °C continuous warming. Different letters indicate statistically significant differences at P < 0.05 using Student's t LSD test.

Mentions: Litter (i.e. standing dead leaf) N concentrations were unaffected by atmospheric CO2 concentration (Table 1 and see Supporting Information—Table S1). There was a marginally significant warming effect (Table 1, Pwarming = 0.047) where litter N concentration averaged across harvests was higher under a continuous warming scenario (9.1 mg g−1) than under ambient warming (7.6 mg g−1). The average of the two warming treatments increased litter N concentration by 25.3 % (Fig. 4C and D). Litter N concentration was most affected by clipping frequency; increased clipping frequency increased litter N concentrations by an average of 95.9 % (Fig. 4B). Consequently, frequent clipping reduced litter C : N ratio from 55.0 to 34.5 averaged across harvests and CO2 and warming treatments (Fig. 3B and see Supporting Information—Table S3). Nitrogen resorption efficiency, calculated as [100 × (green leaf N concentration − litter N concentration)/green leaf N concentration], was decreased from 56.7 % at ambient atmospheric CO2 concentration to 50.9 % under elevated CO2 when averaged across warming and clipping treatments (Fig. 5A). Increased clipping frequency decreased N resorption efficiency from 58.9 % in infrequently clipped plots to 48.7 % in frequently clipped plots when averaged across warming and CO2 treatments (Fig. 5A). Averaged across clipping and CO2 treatment, both warming treatments reduced N resorption efficiency from 59.1 % in the unwarmed treatment to 52.8 and 49.5 % in the high night-time and continuously warmed treatments, respectively.Figure 4.


Effects of elevated atmospheric CO2 concentrations, clipping regimen and differential day/night atmospheric warming on tissue nitrogen concentrations of a perennial pasture grass.

Volder A, Gifford RM, Evans JR - AoB Plants (2015)

(A) Effect of clipping frequency and atmospheric CO2 concentration on N resorption efficiency. (B) Effect of warming treatment on N resorption efficiency, Amb = ambient, HN = +2.2 °C/+4.0 °C day/night warming, CW = +3.0 °C continuous warming. Different letters indicate statistically significant differences at P < 0.05 using Student's t LSD test.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4591745&req=5

PLV094F5: (A) Effect of clipping frequency and atmospheric CO2 concentration on N resorption efficiency. (B) Effect of warming treatment on N resorption efficiency, Amb = ambient, HN = +2.2 °C/+4.0 °C day/night warming, CW = +3.0 °C continuous warming. Different letters indicate statistically significant differences at P < 0.05 using Student's t LSD test.
Mentions: Litter (i.e. standing dead leaf) N concentrations were unaffected by atmospheric CO2 concentration (Table 1 and see Supporting Information—Table S1). There was a marginally significant warming effect (Table 1, Pwarming = 0.047) where litter N concentration averaged across harvests was higher under a continuous warming scenario (9.1 mg g−1) than under ambient warming (7.6 mg g−1). The average of the two warming treatments increased litter N concentration by 25.3 % (Fig. 4C and D). Litter N concentration was most affected by clipping frequency; increased clipping frequency increased litter N concentrations by an average of 95.9 % (Fig. 4B). Consequently, frequent clipping reduced litter C : N ratio from 55.0 to 34.5 averaged across harvests and CO2 and warming treatments (Fig. 3B and see Supporting Information—Table S3). Nitrogen resorption efficiency, calculated as [100 × (green leaf N concentration − litter N concentration)/green leaf N concentration], was decreased from 56.7 % at ambient atmospheric CO2 concentration to 50.9 % under elevated CO2 when averaged across warming and clipping treatments (Fig. 5A). Increased clipping frequency decreased N resorption efficiency from 58.9 % in infrequently clipped plots to 48.7 % in frequently clipped plots when averaged across warming and CO2 treatments (Fig. 5A). Averaged across clipping and CO2 treatment, both warming treatments reduced N resorption efficiency from 59.1 % in the unwarmed treatment to 52.8 and 49.5 % in the high night-time and continuously warmed treatments, respectively.Figure 4.

Bottom Line: Both warming treatments increased leaf N concentrations under ambient CO2 concentrations, but did not significantly alter leaf N concentrations under elevated CO2 concentrations.Nitrogen resorption from leaves was decreased under elevated CO2 conditions as well as by more frequent clipping.Overall, the effects of CO2, warming and clipping treatments on aboveground tissue N concentrations were much greater than on belowground tissue.

View Article: PubMed Central - PubMed

Affiliation: Department of Plant Sciences, University of California - Davis, Davis, CA, USA avolder@ucdavis.edu.

No MeSH data available.