Controls of evapotranspiration and CO2 fluxes from scots pine by surface conductance and abiotic factors.
Evapotranspiration (E) and CO2 flux (Fc ) in the growing season of an unusual dry year were measured continuously over a Scots pine forest in eastern Finland, by eddy covariance techniques. The aims were to gain an understanding of their biological and environmental control processes. As a result, t...
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| Format: | Article |
| Language: | English |
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Public Library of Science (PLoS)
2013-01-01
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| Series: | PLoS ONE |
| Online Access: | http://europepmc.org/articles/PMC3722186?pdf=render |
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| author | Tianshan Zha Chunyi Li Seppo Kellomäki Heli Peltola Kai-Yun Wang Yuqing Zhang |
| author_facet | Tianshan Zha Chunyi Li Seppo Kellomäki Heli Peltola Kai-Yun Wang Yuqing Zhang |
| author_sort | Tianshan Zha |
| collection | DOAJ |
| description | Evapotranspiration (E) and CO2 flux (Fc ) in the growing season of an unusual dry year were measured continuously over a Scots pine forest in eastern Finland, by eddy covariance techniques. The aims were to gain an understanding of their biological and environmental control processes. As a result, there were obvious diurnal and seasonal changes in E, Fc , surface conductance (gc ), and decoupling coefficient (Ω), showing similar trends to those in radiation (PAR) and vapour pressure deficit (δ). The maximum mean daily values (24-h average) for E, Fc , gc , and Ω were 1.78 mmol m(-2) s(-1), -11.18 µmol m(-2) s(-1), 6.27 mm s(-1), and 0.31, respectively, with seasonal averages of 0.71 mmol m(-2) s(-1), -4.61 µmol m(-2) s(-1), 3.3 mm s(-1), and 0.16. E and Fc were controlled by combined biological and environmental variables. There was curvilinear dependence of E on gc and Fc on gc . Among the environmental variables, PAR was the most important factor having a positive linear relationship to E and curvilinear relationship to Fc , while vapour pressure deficit was the most important environmental factor affecting gc . Water use efficiency was slightly higher in the dry season, with mean monthly values ranging from 6.67 to 7.48 μmol CO2 (mmol H2O)(-1) and a seasonal average of 7.06 μmol CO2 (μmol H2O)(-1). Low Ω and its close positive relationship with gc indicate that evapotranspiration was sensitive to surface conductance. Mid summer drought reduced surface conductance and decoupling coefficient, suggesting a more biotic control of evapotranspiration and a physiological acclimation to dry air. Surface conductance remained low and constant under dry condition, supporting that a constant value of surface constant can be used for modelling transpiration under drought condition. |
| first_indexed | 2024-12-24T14:04:02Z |
| format | Article |
| id | doaj.art-ce7bf160673f4320a60b4b3b40bf0316 |
| institution | Directory Open Access Journal |
| issn | 1932-6203 |
| language | English |
| last_indexed | 2024-12-24T14:04:02Z |
| publishDate | 2013-01-01 |
| publisher | Public Library of Science (PLoS) |
| record_format | Article |
| series | PLoS ONE |
| spelling | doaj.art-ce7bf160673f4320a60b4b3b40bf03162022-12-21T16:52:23ZengPublic Library of Science (PLoS)PLoS ONE1932-62032013-01-0187e6902710.1371/journal.pone.0069027Controls of evapotranspiration and CO2 fluxes from scots pine by surface conductance and abiotic factors.Tianshan ZhaChunyi LiSeppo KellomäkiHeli PeltolaKai-Yun WangYuqing ZhangEvapotranspiration (E) and CO2 flux (Fc ) in the growing season of an unusual dry year were measured continuously over a Scots pine forest in eastern Finland, by eddy covariance techniques. The aims were to gain an understanding of their biological and environmental control processes. As a result, there were obvious diurnal and seasonal changes in E, Fc , surface conductance (gc ), and decoupling coefficient (Ω), showing similar trends to those in radiation (PAR) and vapour pressure deficit (δ). The maximum mean daily values (24-h average) for E, Fc , gc , and Ω were 1.78 mmol m(-2) s(-1), -11.18 µmol m(-2) s(-1), 6.27 mm s(-1), and 0.31, respectively, with seasonal averages of 0.71 mmol m(-2) s(-1), -4.61 µmol m(-2) s(-1), 3.3 mm s(-1), and 0.16. E and Fc were controlled by combined biological and environmental variables. There was curvilinear dependence of E on gc and Fc on gc . Among the environmental variables, PAR was the most important factor having a positive linear relationship to E and curvilinear relationship to Fc , while vapour pressure deficit was the most important environmental factor affecting gc . Water use efficiency was slightly higher in the dry season, with mean monthly values ranging from 6.67 to 7.48 μmol CO2 (mmol H2O)(-1) and a seasonal average of 7.06 μmol CO2 (μmol H2O)(-1). Low Ω and its close positive relationship with gc indicate that evapotranspiration was sensitive to surface conductance. Mid summer drought reduced surface conductance and decoupling coefficient, suggesting a more biotic control of evapotranspiration and a physiological acclimation to dry air. Surface conductance remained low and constant under dry condition, supporting that a constant value of surface constant can be used for modelling transpiration under drought condition.http://europepmc.org/articles/PMC3722186?pdf=render |
| spellingShingle | Tianshan Zha Chunyi Li Seppo Kellomäki Heli Peltola Kai-Yun Wang Yuqing Zhang Controls of evapotranspiration and CO2 fluxes from scots pine by surface conductance and abiotic factors. PLoS ONE |
| title | Controls of evapotranspiration and CO2 fluxes from scots pine by surface conductance and abiotic factors. |
| title_full | Controls of evapotranspiration and CO2 fluxes from scots pine by surface conductance and abiotic factors. |
| title_fullStr | Controls of evapotranspiration and CO2 fluxes from scots pine by surface conductance and abiotic factors. |
| title_full_unstemmed | Controls of evapotranspiration and CO2 fluxes from scots pine by surface conductance and abiotic factors. |
| title_short | Controls of evapotranspiration and CO2 fluxes from scots pine by surface conductance and abiotic factors. |
| title_sort | controls of evapotranspiration and co2 fluxes from scots pine by surface conductance and abiotic factors |
| url | http://europepmc.org/articles/PMC3722186?pdf=render |
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