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Modelling strategies of the soil pla...

Manunta, Paolo.

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Modelling strategies of the soil plant atmosphere continuum in water limited environments and elevated atmospheric carbon dioxide.

Record Type:	Language materials, printed : Monograph/item
Title/Author:	Modelling strategies of the soil plant atmosphere continuum in water limited environments and elevated atmospheric carbon dioxide./
Author:	Manunta, Paolo.
Description:	133 p.
Notes:	Adviser: Yongsheng Feng.
Contained By:	Dissertation Abstracts International62-05B.
Subject:	Agriculture, General. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=NQ59998
ISBN:	0612599981

Modelling strategies of the soil plant atmosphere continuum in water limited environments and elevated atmospheric carbon dioxide.
Manunta, Paolo.

Modelling strategies of the soil plant atmosphere continuum in water limited environments and elevated atmospheric carbon dioxide. - 133 p.

Adviser: Yongsheng Feng.

Thesis (Ph.D.)--University of Alberta (Canada), 2000.

The rationale for this study is found in the probable higher temperatures and changes in rainfall patterns that are expected in the future as a result from increasing levels of CO2 in the atmosphere. In particular, higher air temperatures may cause an increase in evapotranspiration (ET) demand while a reduction in rainfall could increase the severity and duration of drought in arid and semi-arid regions. Representation of the water transfer scheme includes water uptake by roots and the interaction between ET and CO 2 enrichment. The predicted response of a plant canopy, in terms of energy exchange processes to elevated atmospheric CO2 level, was tested against measurements collected in the field. Simulated and measured canopy conductances were reduced by about 30% under elevated [CO 2] under optimum conditions of water supply. Reductions in latent heat fluxes under elevated vs. ambient [CO2] caused reductions in both simulated and measured seasonal water use of 6% under optimum and 2% under suboptimum irrigation. This modelling framework was extended to explore adaptation and functioning of root system of woody plant canopies. A theoretical analysis of a recently observed phenomenon called “hydraulic lift” was conducted. Simulated results support the hypothesis that the water relocated via hydraulic lift prevents the upper soil layers from becoming extremely dry. In particular the soil layers close to the surface maintained soil water potential between −1.0 and −1.3 MPa during the drought period and under two different rainfall regimes. Conversely the absence of hydraulic lift caused the soil layer close to the surface (0.0–0.1 m) to drop to −20 MPa and −28 MPa. Water relocated via hydraulic lift did not provide a significant additional amount of water for plant transpiration. In conclusion, modelling of CO2 and transpiration interactions may produce more accurate estimates of canopy water use under predicted climate change. Hydraulic lift was simulated to be more important for soil moisture re-distribution than for canopy transpiration.

ISBN: 0612599981Subjects--Topical Terms:

1017510
Agriculture, General.

Modelling strategies of the soil plant atmosphere continuum in water limited environments and elevated atmospheric carbon dioxide.
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100 1 $a Manunta, Paolo. $3 1249368
245 1 0 $a Modelling strategies of the soil plant atmosphere continuum in water limited environments and elevated atmospheric carbon dioxide.
300 $a 133 p.
500 $a Adviser: Yongsheng Feng.
500 $a Source: Dissertation Abstracts International, Volume: 62-05, Section: B, page: 2235.
502 $a Thesis (Ph.D.)--University of Alberta (Canada), 2000.
520 $a The rationale for this study is found in the probable higher temperatures and changes in rainfall patterns that are expected in the future as a result from increasing levels of CO2 in the atmosphere. In particular, higher air temperatures may cause an increase in evapotranspiration (ET) demand while a reduction in rainfall could increase the severity and duration of drought in arid and semi-arid regions. Representation of the water transfer scheme includes water uptake by roots and the interaction between ET and CO 2 enrichment. The predicted response of a plant canopy, in terms of energy exchange processes to elevated atmospheric CO2 level, was tested against measurements collected in the field. Simulated and measured canopy conductances were reduced by about 30% under elevated [CO 2] under optimum conditions of water supply. Reductions in latent heat fluxes under elevated vs. ambient [CO2] caused reductions in both simulated and measured seasonal water use of 6% under optimum and 2% under suboptimum irrigation. This modelling framework was extended to explore adaptation and functioning of root system of woody plant canopies. A theoretical analysis of a recently observed phenomenon called “hydraulic lift” was conducted. Simulated results support the hypothesis that the water relocated via hydraulic lift prevents the upper soil layers from becoming extremely dry. In particular the soil layers close to the surface maintained soil water potential between −1.0 and −1.3 MPa during the drought period and under two different rainfall regimes. Conversely the absence of hydraulic lift caused the soil layer close to the surface (0.0–0.1 m) to drop to −20 MPa and −28 MPa. Water relocated via hydraulic lift did not provide a significant additional amount of water for plant transpiration. In conclusion, modelling of CO2 and transpiration interactions may produce more accurate estimates of canopy water use under predicted climate change. Hydraulic lift was simulated to be more important for soil moisture re-distribution than for canopy transpiration.
590 $a School code: 0351.
650 4 $a Agriculture, General. $3 1017510
650 4 $a Biology, Ecology. $3 1017726
650 4 $a Environmental Sciences. $3 676987
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710 2 0 $a University of Alberta (Canada). $3 626651
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791 $a Ph.D.
792 $a 2000
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=NQ59998