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Ecosystem carbon and water budgets u...

Lund, Christopher Paul.

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Ecosystem carbon and water budgets under elevated atmospheric carbon dioxide concentration in two California grasslands.

Record Type:	Language materials, printed : Monograph/item
Title/Author:	Ecosystem carbon and water budgets under elevated atmospheric carbon dioxide concentration in two California grasslands./
Author:	Lund, Christopher Paul.
Description:	161 p.
Notes:	Adviser: Christopher B. Field.
Contained By:	Dissertation Abstracts International63-01B.
Subject:	Biogeochemistry. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3040040
ISBN:	0493533524

Ecosystem carbon and water budgets under elevated atmospheric carbon dioxide concentration in two California grasslands.
Lund, Christopher Paul.

Ecosystem carbon and water budgets under elevated atmospheric carbon dioxide concentration in two California grasslands. - 161 p.

Adviser: Christopher B. Field.

Thesis (Ph.D.)--Stanford University, 2002.

Stomatal conductance and photosynthesis play central roles in regulating the fluxes of water (H2O) and carbon (C) between the land surface and the atmosphere. Anthropogenically driven increases in atmospheric carbon dioxide (CO2) concentration may have a significant impact on these fluxes by decreasing stomatal conductance and increasing photosynthesis. Here, using a combination of gas-exchange and modeling results, I describe the effects of elevated atmospheric CO2 concentration (720 ppmv) on ecosystem water and carbon budgets in serpentine and sanstone annual grasslands. Averaged across grasslands, daily evapotranspiration (ET) decreased by an average of 0.53 mm H2O day<super>−1</super> under elevated CO2 during the winter and spring months. Decreases in ET were accompanied by increases in soil moisture and deep drainage. During the summer, early season water savings resulted in an average ET increase of 0.12 mm H 2O day<super>−1</super> under elevated CO2. On an annual basis, simulation results show that ET decreased by an average of 26.5 mm H2O y<super>−1</super>. For the net ecosystem CO2 exchange analyses, I used soil CO2 flux measurements in conjunction with a soil CO2 transport model to remove the bias introduced by chamber pressurization. In the sandstone grassland, net ecosystem production (NEP) increased from 55.6 g C m<super>−2</super> y<super>−1</super> under ambient CO2 to 59.6 g C m<super>−2</super> y<super> −1</super> under elevated CO2, a difference of 4.0 g C m<super> −2</super>. Annual canopy net photosynthesis (An) increased under elevated CO2 by 35.8 g C m<super>−2</super> y<super> −1</super>, but the bulk of this increase was returned to the atmosphere via root and heterotrophic respiration. Canopy An decreased under elevated CO2 early in the growing season, an observation that may reflect nitrogen limitation. These results suggest that future increases in atmospheric CO2 concentration will significantly reduce evapotranspiration but have only minimal effects on ecosystem C uptake.

ISBN: 0493533524Subjects--Topical Terms:

545717
Biogeochemistry.

Ecosystem carbon and water budgets under elevated atmospheric carbon dioxide concentration in two California grasslands.
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020 $a 0493533524
035 $a (UnM)AAI3040040
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040 $a UnM $c UnM
100 1 $a Lund, Christopher Paul. $3 1251702
245 1 0 $a Ecosystem carbon and water budgets under elevated atmospheric carbon dioxide concentration in two California grasslands.
300 $a 161 p.
500 $a Adviser: Christopher B. Field.
500 $a Source: Dissertation Abstracts International, Volume: 63-01, Section: B, page: 0133.
502 $a Thesis (Ph.D.)--Stanford University, 2002.
520 $a Stomatal conductance and photosynthesis play central roles in regulating the fluxes of water (H2O) and carbon (C) between the land surface and the atmosphere. Anthropogenically driven increases in atmospheric carbon dioxide (CO2) concentration may have a significant impact on these fluxes by decreasing stomatal conductance and increasing photosynthesis. Here, using a combination of gas-exchange and modeling results, I describe the effects of elevated atmospheric CO2 concentration (720 ppmv) on ecosystem water and carbon budgets in serpentine and sanstone annual grasslands. Averaged across grasslands, daily evapotranspiration (ET) decreased by an average of 0.53 mm H2O day<super>−1</super> under elevated CO2 during the winter and spring months. Decreases in ET were accompanied by increases in soil moisture and deep drainage. During the summer, early season water savings resulted in an average ET increase of 0.12 mm H 2O day<super>−1</super> under elevated CO2. On an annual basis, simulation results show that ET decreased by an average of 26.5 mm H2O y<super>−1</super>. For the net ecosystem CO2 exchange analyses, I used soil CO2 flux measurements in conjunction with a soil CO2 transport model to remove the bias introduced by chamber pressurization. In the sandstone grassland, net ecosystem production (NEP) increased from 55.6 g C m<super>−2</super> y<super>−1</super> under ambient CO2 to 59.6 g C m<super>−2</super> y<super> −1</super> under elevated CO2, a difference of 4.0 g C m<super> −2</super>. Annual canopy net photosynthesis (An) increased under elevated CO2 by 35.8 g C m<super>−2</super> y<super> −1</super>, but the bulk of this increase was returned to the atmosphere via root and heterotrophic respiration. Canopy An decreased under elevated CO2 early in the growing season, an observation that may reflect nitrogen limitation. These results suggest that future increases in atmospheric CO2 concentration will significantly reduce evapotranspiration but have only minimal effects on ecosystem C uptake.
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