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Experimental vs. modeled water use in mature Norway spruce (Picea abies) exposed to elevated CO(2).

Leuzinger S, Bader MK - Front Plant Sci (2012)

Bottom Line: Rising levels of atmospheric CO(2) have often been reported to reduce plant water use.Here, we provide first results from a free air CO(2) enrichment (FACE) experiment with naturally growing, mature (35 m) Picea abies (L.) (Norway spruce) and compare them to simulations by the DGVM LPJ-GUESS.Using LPJ-GUESS, we simulated this experiment using climate data from a nearby weather station.

View Article: PubMed Central - PubMed

Affiliation: School of Applied Sciences, Auckland University of Technology Auckland, New Zealand ; Forest Ecology, ETH Zurich Zurich, Switzerland ; Institute of Botany, University of Basel Basel, Switzerland.

ABSTRACT
Rising levels of atmospheric CO(2) have often been reported to reduce plant water use. Such behavior is also predicted by standard equations relating photosynthesis, stomatal conductance, and atmospheric CO(2) concentration, which form the core of dynamic global vegetation models (DGVMs). Here, we provide first results from a free air CO(2) enrichment (FACE) experiment with naturally growing, mature (35 m) Picea abies (L.) (Norway spruce) and compare them to simulations by the DGVM LPJ-GUESS. We monitored sap flow, stem water deficit, stomatal conductance, leaf water potential, and soil moisture in five 35-40 m tall CO(2)-treated (550 ppm) trees over two seasons. Using LPJ-GUESS, we simulated this experiment using climate data from a nearby weather station. While the model predicted a stable reduction of transpiration of between 9% and 18% (at concentrations of 550-700 ppm atmospheric CO(2)), the combined evidence from various methods characterizing water use in our experimental trees suggest no changes in response to future CO(2) concentrations. The discrepancy between the modeled and the experimental results may be a scaling issue: while dynamic vegetation models correctly predict leaf-level responses, they may not sufficiently account for the processes involved at the canopy and ecosystem scale, which could offset the first-order stomatal response.

No MeSH data available.


Related in: MedlinePlus

Stem water deficit in control and CO2-treated P. abies trees. (A) Standardized time series of stem water deficit in CO2-treated (bold) and control (dashed line) trees, growth-trend corrected (see section “Materials and Methods”). (B) Soil water content measured in the 10 cm top soil layer for the control and treated area. The insets show that there are no systematic differences between CO2-treated and control trees during any of the three periods.
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Figure 3: Stem water deficit in control and CO2-treated P. abies trees. (A) Standardized time series of stem water deficit in CO2-treated (bold) and control (dashed line) trees, growth-trend corrected (see section “Materials and Methods”). (B) Soil water content measured in the 10 cm top soil layer for the control and treated area. The insets show that there are no systematic differences between CO2-treated and control trees during any of the three periods.

Mentions: The relationship between stem water deficit (ΔW) and soil moisture (sm) was modeled individually for the pre-treatment and the two FACE periods (season 2009 and 2010) using a 2-parameter Michaelis-Menten-type hyperbola: ΔW = a × sm/(b + sm), where “a” is the asymptote and “b” the soil moisture level at which stem water deficit reaches half of its asymptotic value (Figure 3).


Experimental vs. modeled water use in mature Norway spruce (Picea abies) exposed to elevated CO(2).

Leuzinger S, Bader MK - Front Plant Sci (2012)

Stem water deficit in control and CO2-treated P. abies trees. (A) Standardized time series of stem water deficit in CO2-treated (bold) and control (dashed line) trees, growth-trend corrected (see section “Materials and Methods”). (B) Soil water content measured in the 10 cm top soil layer for the control and treated area. The insets show that there are no systematic differences between CO2-treated and control trees during any of the three periods.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3472548&req=5

Figure 3: Stem water deficit in control and CO2-treated P. abies trees. (A) Standardized time series of stem water deficit in CO2-treated (bold) and control (dashed line) trees, growth-trend corrected (see section “Materials and Methods”). (B) Soil water content measured in the 10 cm top soil layer for the control and treated area. The insets show that there are no systematic differences between CO2-treated and control trees during any of the three periods.
Mentions: The relationship between stem water deficit (ΔW) and soil moisture (sm) was modeled individually for the pre-treatment and the two FACE periods (season 2009 and 2010) using a 2-parameter Michaelis-Menten-type hyperbola: ΔW = a × sm/(b + sm), where “a” is the asymptote and “b” the soil moisture level at which stem water deficit reaches half of its asymptotic value (Figure 3).

Bottom Line: Rising levels of atmospheric CO(2) have often been reported to reduce plant water use.Here, we provide first results from a free air CO(2) enrichment (FACE) experiment with naturally growing, mature (35 m) Picea abies (L.) (Norway spruce) and compare them to simulations by the DGVM LPJ-GUESS.Using LPJ-GUESS, we simulated this experiment using climate data from a nearby weather station.

View Article: PubMed Central - PubMed

Affiliation: School of Applied Sciences, Auckland University of Technology Auckland, New Zealand ; Forest Ecology, ETH Zurich Zurich, Switzerland ; Institute of Botany, University of Basel Basel, Switzerland.

ABSTRACT
Rising levels of atmospheric CO(2) have often been reported to reduce plant water use. Such behavior is also predicted by standard equations relating photosynthesis, stomatal conductance, and atmospheric CO(2) concentration, which form the core of dynamic global vegetation models (DGVMs). Here, we provide first results from a free air CO(2) enrichment (FACE) experiment with naturally growing, mature (35 m) Picea abies (L.) (Norway spruce) and compare them to simulations by the DGVM LPJ-GUESS. We monitored sap flow, stem water deficit, stomatal conductance, leaf water potential, and soil moisture in five 35-40 m tall CO(2)-treated (550 ppm) trees over two seasons. Using LPJ-GUESS, we simulated this experiment using climate data from a nearby weather station. While the model predicted a stable reduction of transpiration of between 9% and 18% (at concentrations of 550-700 ppm atmospheric CO(2)), the combined evidence from various methods characterizing water use in our experimental trees suggest no changes in response to future CO(2) concentrations. The discrepancy between the modeled and the experimental results may be a scaling issue: while dynamic vegetation models correctly predict leaf-level responses, they may not sufficiently account for the processes involved at the canopy and ecosystem scale, which could offset the first-order stomatal response.

No MeSH data available.


Related in: MedlinePlus