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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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Variation in mean Fagus sylvatica and Nothofagus spp. δ13C, Δ13C, δ18O, Ci, iWUE, and BAI.Symbols with the error bars (±1 standard error, n = 4) are means of individuals per site in 10-years total values (±1 standard error n = 4). Temporal trends of Ca and atmospheric δ13C are also reported (dashed lines). Sites are referred to by symbols in the legend: Pian del Cansiglio, Sasso Fratino, Val Cervara, and Montedimezzo (North-Central Italy); Gargano, Cilento, Aspromonte, and Sila (Southern Italy); Omora low, Omora high, Torres del Paine, Villarrica, and Chillan (Chile). Site and species details are reported in Table 1. Populations are listed from North to South (Northern Hemisphere) or South to North (Southern Hemisphere).
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pone-0113136-g002: Variation in mean Fagus sylvatica and Nothofagus spp. δ13C, Δ13C, δ18O, Ci, iWUE, and BAI.Symbols with the error bars (±1 standard error, n = 4) are means of individuals per site in 10-years total values (±1 standard error n = 4). Temporal trends of Ca and atmospheric δ13C are also reported (dashed lines). Sites are referred to by symbols in the legend: Pian del Cansiglio, Sasso Fratino, Val Cervara, and Montedimezzo (North-Central Italy); Gargano, Cilento, Aspromonte, and Sila (Southern Italy); Omora low, Omora high, Torres del Paine, Villarrica, and Chillan (Chile). Site and species details are reported in Table 1. Populations are listed from North to South (Northern Hemisphere) or South to North (Southern Hemisphere).

Mentions: In general terms, similar trends in δ13C, Δ13C, δ18O, Ci and iWUE were found throughout the chronologies corresponding to F. sylvatica and Notophagus spp. trees from the different forest sites (Fig. 2). Tree rings δ13C on forest trees showed variable patterns (e.g., increasing at Torres del Paine, while decreasing at Omora high). When the atmospheric effect over plants carbon isotopic ratios is excluded, the discrimination (Δ13C) trends during the past decades showed the opposite (decreasing) trend. The more negative δ13C values resulted in higher discrimination (Δ13C) and lower iWUE. Yet, δ18O showed relatively stable patterns throughout the past century, with some increases in the last thirty years in several sites, but not in others.


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)

Variation in mean Fagus sylvatica and Nothofagus spp. δ13C, Δ13C, δ18O, Ci, iWUE, and BAI.Symbols with the error bars (±1 standard error, n = 4) are means of individuals per site in 10-years total values (±1 standard error n = 4). Temporal trends of Ca and atmospheric δ13C are also reported (dashed lines). Sites are referred to by symbols in the legend: Pian del Cansiglio, Sasso Fratino, Val Cervara, and Montedimezzo (North-Central Italy); Gargano, Cilento, Aspromonte, and Sila (Southern Italy); Omora low, Omora high, Torres del Paine, Villarrica, and Chillan (Chile). Site and species details are reported in Table 1. Populations are listed from North to South (Northern Hemisphere) or South to North (Southern Hemisphere).
© Copyright Policy
Related In: Results  -  Collection

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

pone-0113136-g002: Variation in mean Fagus sylvatica and Nothofagus spp. δ13C, Δ13C, δ18O, Ci, iWUE, and BAI.Symbols with the error bars (±1 standard error, n = 4) are means of individuals per site in 10-years total values (±1 standard error n = 4). Temporal trends of Ca and atmospheric δ13C are also reported (dashed lines). Sites are referred to by symbols in the legend: Pian del Cansiglio, Sasso Fratino, Val Cervara, and Montedimezzo (North-Central Italy); Gargano, Cilento, Aspromonte, and Sila (Southern Italy); Omora low, Omora high, Torres del Paine, Villarrica, and Chillan (Chile). Site and species details are reported in Table 1. Populations are listed from North to South (Northern Hemisphere) or South to North (Southern Hemisphere).
Mentions: In general terms, similar trends in δ13C, Δ13C, δ18O, Ci and iWUE were found throughout the chronologies corresponding to F. sylvatica and Notophagus spp. trees from the different forest sites (Fig. 2). Tree rings δ13C on forest trees showed variable patterns (e.g., increasing at Torres del Paine, while decreasing at Omora high). When the atmospheric effect over plants carbon isotopic ratios is excluded, the discrimination (Δ13C) trends during the past decades showed the opposite (decreasing) trend. The more negative δ13C values resulted in higher discrimination (Δ13C) and lower iWUE. Yet, δ18O showed relatively stable patterns throughout the past century, with some increases in the last thirty years in several sites, but not in others.

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