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Climate change at northern latitudes: rising atmospheric humidity decreases transpiration, N-uptake and growth rate of hybrid aspen.

Tullus A, Kupper P, Sellin A, Parts L, Sõber J, Tullus T, Lõhmus K, Sõber A, Tullus H - PLoS ONE (2012)

Bottom Line: Elevated air humidity significantly reduced height, stem diameter and stem volume increments and transpiration of the trees whereas these effects remained highly significant also after considering the side effects from soil-related confounders within the 2.7 ha study area.The lower growth rate in the humidified plots can be partly explained by a decrease in transpiration-driven mass flow of NO(3) (-) in soil, resulting in a significant reduction in the measured uptake of N to foliage in the H plots.The results suggest that the potential growth improvement of fast-growing trees like aspens, due to increasing temperature and atmospheric CO(2) concentration, might be smaller than expected at high latitudes if a rise in atmospheric humidity simultaneously takes place.

View Article: PubMed Central - PubMed

Affiliation: Department of Silviculture, Institute of Forestry and Rural Engineering, Estonian University of Life Sciences, Tartu, Estonia.

ABSTRACT
At northern latitudes a rise in atmospheric humidity and precipitation is predicted as a consequence of global climate change. We studied several growth and functional traits of hybrid aspen (Populus tremula L.×P. tremuloides Michx.) in response to elevated atmospheric humidity (on average 7% over the ambient level) in a free air experimental facility during three growing seasons (2008-2010) in Estonia, which represents northern temperate climate (boreo-nemoral zone). Data were collected from three humidified (H) and three control (C) plots, and analysed using nested linear models. Elevated air humidity significantly reduced height, stem diameter and stem volume increments and transpiration of the trees whereas these effects remained highly significant also after considering the side effects from soil-related confounders within the 2.7 ha study area. Tree leaves were smaller, lighter and had lower leaf mass per area (LMA) in H plots. The magnitude and significance of the humidity treatment effect--inhibition of above-ground growth rate--was more pronounced in larger trees. The lower growth rate in the humidified plots can be partly explained by a decrease in transpiration-driven mass flow of NO(3) (-) in soil, resulting in a significant reduction in the measured uptake of N to foliage in the H plots. The results suggest that the potential growth improvement of fast-growing trees like aspens, due to increasing temperature and atmospheric CO(2) concentration, might be smaller than expected at high latitudes if a rise in atmospheric humidity simultaneously takes place.

Show MeSH
Comparison of physiological traits: a) F – total sap flow, b) FD – sap flux density, c) WUE – water-use efficiency of hybrid aspens at the ages of 3 and 4 years in control (C) and humidified (H) plots (t-test) and summary effect of the treatment over two years (model), whiskers denote ± standard error.
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pone-0042648-g006: Comparison of physiological traits: a) F – total sap flow, b) FD – sap flux density, c) WUE – water-use efficiency of hybrid aspens at the ages of 3 and 4 years in control (C) and humidified (H) plots (t-test) and summary effect of the treatment over two years (model), whiskers denote ± standard error.

Mentions: The distinction in water use characteristics was more pronounced during the third growing season, with almost two times lower estimates of sap flow (F) and sap flux density (FD) in H plots (Fig. 6). At the same time water-use efficiency (WUE) was higher in H plots. Across the whole study period, F was more strongly affected by the treatment than FD (Fig. 4b). Both F and FD varied between the study years, whereas FD was strongly affected by the year×treatment interaction (Table S2).


Climate change at northern latitudes: rising atmospheric humidity decreases transpiration, N-uptake and growth rate of hybrid aspen.

Tullus A, Kupper P, Sellin A, Parts L, Sõber J, Tullus T, Lõhmus K, Sõber A, Tullus H - PLoS ONE (2012)

Comparison of physiological traits: a) F – total sap flow, b) FD – sap flux density, c) WUE – water-use efficiency of hybrid aspens at the ages of 3 and 4 years in control (C) and humidified (H) plots (t-test) and summary effect of the treatment over two years (model), whiskers denote ± standard error.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3412825&req=5

pone-0042648-g006: Comparison of physiological traits: a) F – total sap flow, b) FD – sap flux density, c) WUE – water-use efficiency of hybrid aspens at the ages of 3 and 4 years in control (C) and humidified (H) plots (t-test) and summary effect of the treatment over two years (model), whiskers denote ± standard error.
Mentions: The distinction in water use characteristics was more pronounced during the third growing season, with almost two times lower estimates of sap flow (F) and sap flux density (FD) in H plots (Fig. 6). At the same time water-use efficiency (WUE) was higher in H plots. Across the whole study period, F was more strongly affected by the treatment than FD (Fig. 4b). Both F and FD varied between the study years, whereas FD was strongly affected by the year×treatment interaction (Table S2).

Bottom Line: Elevated air humidity significantly reduced height, stem diameter and stem volume increments and transpiration of the trees whereas these effects remained highly significant also after considering the side effects from soil-related confounders within the 2.7 ha study area.The lower growth rate in the humidified plots can be partly explained by a decrease in transpiration-driven mass flow of NO(3) (-) in soil, resulting in a significant reduction in the measured uptake of N to foliage in the H plots.The results suggest that the potential growth improvement of fast-growing trees like aspens, due to increasing temperature and atmospheric CO(2) concentration, might be smaller than expected at high latitudes if a rise in atmospheric humidity simultaneously takes place.

View Article: PubMed Central - PubMed

Affiliation: Department of Silviculture, Institute of Forestry and Rural Engineering, Estonian University of Life Sciences, Tartu, Estonia.

ABSTRACT
At northern latitudes a rise in atmospheric humidity and precipitation is predicted as a consequence of global climate change. We studied several growth and functional traits of hybrid aspen (Populus tremula L.×P. tremuloides Michx.) in response to elevated atmospheric humidity (on average 7% over the ambient level) in a free air experimental facility during three growing seasons (2008-2010) in Estonia, which represents northern temperate climate (boreo-nemoral zone). Data were collected from three humidified (H) and three control (C) plots, and analysed using nested linear models. Elevated air humidity significantly reduced height, stem diameter and stem volume increments and transpiration of the trees whereas these effects remained highly significant also after considering the side effects from soil-related confounders within the 2.7 ha study area. Tree leaves were smaller, lighter and had lower leaf mass per area (LMA) in H plots. The magnitude and significance of the humidity treatment effect--inhibition of above-ground growth rate--was more pronounced in larger trees. The lower growth rate in the humidified plots can be partly explained by a decrease in transpiration-driven mass flow of NO(3) (-) in soil, resulting in a significant reduction in the measured uptake of N to foliage in the H plots. The results suggest that the potential growth improvement of fast-growing trees like aspens, due to increasing temperature and atmospheric CO(2) concentration, might be smaller than expected at high latitudes if a rise in atmospheric humidity simultaneously takes place.

Show MeSH