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Tree-ring stable isotopes reveal twentieth-century increases in water-use efficiency of Fagus sylvatica and Nothofagus spp. in Italian and Chilean mountains.

Tognetti R, Lombardi F, Lasserre B, Cherubini P, Marchetti M - PLoS ONE (2014)

Bottom Line: A continuous enhancement in isotope-derived iWUE was observed throughout the twentieth century, which was common to all sites and related to changes in Ca (ambient CO2 concentration) and secondarily to increases in temperature.In contrast to other studies, we observed a general increasing trend of BAI, with the exception of F. sylvatica in Aspromonte.The substantial warming observed during the twentieth century did not result in a clear pattern of increased drought stress along these latitudinal transects, because of the variability in temporal trends of precipitation and in specific responses of populations.

View Article: PubMed Central - PubMed

Affiliation: Dipartimento di Bioscienze e Territorio, Università degli Studi del Molise, Pesche, Italy; The EFI Project Centre on Mountain Forests (MOUNTFOR), Edmund Mach Foundation, San Michele all'Adige, Italy.

ABSTRACT
Changes in intrinsic water use efficiency (iWUE) were investigated in Fagus sylvatica and Nothofagus spp. over the last century. We combined dendrochronological methods with dual-isotope analysis to investigate whether atmospheric changes enhanced iWUE of Fagus and Nothofagus and tree growth (basal area increment, BAI) along latitudinal gradients in Italy and Chile. Post-maturation phases of the trees presented different patterns in δ13C, Δ13C, δ18O, Ci (internal CO2 concentration), iWUE, and BAI. A continuous enhancement in isotope-derived iWUE was observed throughout the twentieth century, which was common to all sites and related to changes in Ca (ambient CO2 concentration) and secondarily to increases in temperature. In contrast to other studies, we observed a general increasing trend of BAI, with the exception of F. sylvatica in Aspromonte. Both iWUE and BAI were uncoupled with the estimated drought index, which is in agreement with the absence of enduring decline in tree growth. In general, δ13C and δ18O showed a weak relationship, suggesting the major influence of photosynthetic rate on Ci and δ13C, and the minor contribution of the regulation of stomatal conductance to iWUE. The substantial warming observed during the twentieth century did not result in a clear pattern of increased drought stress along these latitudinal transects, because of the variability in temporal trends of precipitation and in specific responses of populations.

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Temporal evolution of drought index (DI = P−ETo) calculated for the period beginning October (Italy) or April (Chile) of the previous year and ending with September (Italy) or March (Chile) of the current year, and used to select climatically contrasting years.It must be pointed out that the great heterogeneity of the local environment in these mountainous areas can contribute errors to estimated values of drought index.
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pone-0113136-g001: Temporal evolution of drought index (DI = P−ETo) calculated for the period beginning October (Italy) or April (Chile) of the previous year and ending with September (Italy) or March (Chile) of the current year, and used to select climatically contrasting years.It must be pointed out that the great heterogeneity of the local environment in these mountainous areas can contribute errors to estimated values of drought index.

Mentions: A downward trend of climate index at the end of last century, indicating increasingly drier conditions, was found for Val Cervara, Sasso Fratino and Montedimezzo (Fig. 1). However, the climate index was variable from year to year and below −25 mm only in several years (and only for Val Cervara, Gargano, Cilento and Chillan), indicating that trees were rarely subjected to severe and prolonged drought stress over the past century.


Tree-ring stable isotopes reveal twentieth-century increases in water-use efficiency of Fagus sylvatica and Nothofagus spp. in Italian and Chilean mountains.

Tognetti R, Lombardi F, Lasserre B, Cherubini P, Marchetti M - PLoS ONE (2014)

Temporal evolution of drought index (DI = P−ETo) calculated for the period beginning October (Italy) or April (Chile) of the previous year and ending with September (Italy) or March (Chile) of the current year, and used to select climatically contrasting years.It must be pointed out that the great heterogeneity of the local environment in these mountainous areas can contribute errors to estimated values of drought index.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4232607&req=5

pone-0113136-g001: Temporal evolution of drought index (DI = P−ETo) calculated for the period beginning October (Italy) or April (Chile) of the previous year and ending with September (Italy) or March (Chile) of the current year, and used to select climatically contrasting years.It must be pointed out that the great heterogeneity of the local environment in these mountainous areas can contribute errors to estimated values of drought index.
Mentions: A downward trend of climate index at the end of last century, indicating increasingly drier conditions, was found for Val Cervara, Sasso Fratino and Montedimezzo (Fig. 1). However, the climate index was variable from year to year and below −25 mm only in several years (and only for Val Cervara, Gargano, Cilento and Chillan), indicating that trees were rarely subjected to severe and prolonged drought stress over the past century.

Bottom Line: A continuous enhancement in isotope-derived iWUE was observed throughout the twentieth century, which was common to all sites and related to changes in Ca (ambient CO2 concentration) and secondarily to increases in temperature.In contrast to other studies, we observed a general increasing trend of BAI, with the exception of F. sylvatica in Aspromonte.The substantial warming observed during the twentieth century did not result in a clear pattern of increased drought stress along these latitudinal transects, because of the variability in temporal trends of precipitation and in specific responses of populations.

View Article: PubMed Central - PubMed

Affiliation: Dipartimento di Bioscienze e Territorio, Università degli Studi del Molise, Pesche, Italy; The EFI Project Centre on Mountain Forests (MOUNTFOR), Edmund Mach Foundation, San Michele all'Adige, Italy.

ABSTRACT
Changes in intrinsic water use efficiency (iWUE) were investigated in Fagus sylvatica and Nothofagus spp. over the last century. We combined dendrochronological methods with dual-isotope analysis to investigate whether atmospheric changes enhanced iWUE of Fagus and Nothofagus and tree growth (basal area increment, BAI) along latitudinal gradients in Italy and Chile. Post-maturation phases of the trees presented different patterns in δ13C, Δ13C, δ18O, Ci (internal CO2 concentration), iWUE, and BAI. A continuous enhancement in isotope-derived iWUE was observed throughout the twentieth century, which was common to all sites and related to changes in Ca (ambient CO2 concentration) and secondarily to increases in temperature. In contrast to other studies, we observed a general increasing trend of BAI, with the exception of F. sylvatica in Aspromonte. Both iWUE and BAI were uncoupled with the estimated drought index, which is in agreement with the absence of enduring decline in tree growth. In general, δ13C and δ18O showed a weak relationship, suggesting the major influence of photosynthetic rate on Ci and δ13C, and the minor contribution of the regulation of stomatal conductance to iWUE. The substantial warming observed during the twentieth century did not result in a clear pattern of increased drought stress along these latitudinal transects, because of the variability in temporal trends of precipitation and in specific responses of populations.

Show MeSH
Related in: MedlinePlus