Inter- and intra-annual stable carbon and oxygen isotope signals in response to drought in Mediterranean pines

Sarris, Dimitrios; Siegwolf, Rolf; Körner, Christian

doi:10.1016/j.agrformet.2012.08.007

Cited by 141 publications

(116 citation statements)

References 49 publications

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“…The positive correlation between the values of δ 13 C and productivity has also been reported in other studies (SARRIS et al, 2013) and may be due to a lower stomata conductance associated with the maintenance of the photosynthetic rate by the tolerant clone (DUCREY et al, 2008). This suggests that this clone has mechanisms that provide a greater transpiration efficiency and hence higher productivity than the drought-sensitive one when growing in environments under severe water deficit.…”

supporting

confidence: 58%

Carbon isotope discrimination and differential drought tolerance in eucalypt clones

Nunes¹,

Barros²,

Novais³

et al. 2016

Sci. For.

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ResumoUma estratégia utilizada para superar a limitação por água é o uso de materiais genéticos tolerantes à seca, com maior eficiência de utilização da água (EUA). A EUA está associada à discriminação isotópica do 13 C (δ 13 C), que pode refletir resposta integrada das árvores ao estresse hídrico durante seu ciclo de vida. O objetivo desse trabalho foi verificar a relação entre δ 13 C e a tolerância ao déficit hídrico de dois clones de eucalipto, cultivados na região do cerrado. Plantios com espaçamento entre plantas de 3x3 m, de duas regiões do norte de Minas Gerais, Brasil, com quatro anos de idade, com clones de eucalipto sensível ou tolerante ao déficit hídrico, foram amostrados no fim da estação seca de 2007. Foi determinado o potencial hídrico foliar (Ψ wf ) e δ 13 C para os dois clones, nas duas regiões. Passados dois anos, nos mesmos locais, foram determinados o índice de sobrevivência de plantas e o volume de madeira das plantas vivas e das mortas, em parcelas com espaçamento 3x3 m (espaçamento original), 3x4 e 4x6 m em uma das regiões, e 3x3, 3x6 e 4x6 m na outra região. O clone tolerante ao déficit hídrico apresentou menor δ 13 C (-26.3 ‰ versus -27.4 ‰) e Ψ wf (-1.7 MPa versus -1.3 MPa), que o sensível. O clone tolerante também apresentou maior índice de sobrevivência e maior produtividade. Os resultados sugerem que o uso da δ 13 C, como indicador de clones de eucalipto tolerantes ao déficit hídrico, requer melhor entendimento dos processos que controlam esta característica.Palavras-chave: déficit hídrico, Eucalyptus urophylla, produtividade florestal. AbstractWater stress is the main constraint to Eucalyptus growth in the Brazilian cerrado -a savannah type of vegetation. A strategy to overcome this constraint is the use of drought tolerance genotypes, with higher water use efficiency (WUE). WUE has been linked to isotopic discrimination of 13 C (δ 13 C) which may reflect the time-integrated tree responses to drought stress during its lifespan. The relationship between δ 13 C and water stress tolerance of two contrasting Eucalyptus clones cultivated in the cerrado region was investigated. Sites with four-year-old trees of a drought-sensitive and a drought-tolerant clone, planted in a 3 x 3 m spacing, in two regions of Minas Gerais State, Brazil, were sampled in 2007 in the end of an extreme dry season. Leaf water potentials (Ψ wf ) and δ 13 C were determined for both clones in both regions. Two years later, in the same location, assessments of survival rates and stem volumes of dead and living trees were performed in plots with 3x3 m (the original spacing), 3x4 m and 4x6 m in one region, and 3x3 m, 3x6 m and 4x6 m in the other region. The drought-tolerant clone showed a slightly lower δ 13 C (-26.3 ‰ versus -27.4 ‰) and Ψ wf (-1.7 MPa versus -1.3 MPa) than the sensitive one. The tolerant clone also had a higher survival rate and yield. The results suggest that the use of δ 13 C as an indicator of drought tolerance for Eucalypt clones requires a better understanding of the underlying processes that c...

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supporting

confidence: 58%

Carbon isotope discrimination and differential drought tolerance in eucalypt clones

Nunes¹,

Barros²,

Novais³

et al. 2016

Sci. For.

View full text Add to dashboard Cite

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“…Barbour et al, 2002;Sarris et al, 2013), but there is a lack of focus in the literature on relating these changes to the discrete hydrological processes which control the availability of water at the rooting zone. Furthermore, to date, most studies have relied on differences between cellulosic isotope values from tree rings to infer water source variations, without deconvolving the actual signature of source water (Marshall and Monserud, 2006;Singer et al, 2013).…”

Section: Discussionmentioning

confidence: 99%

“…O values for Pinus radiata reflected the seasonal variations in water source use as did Sarris et al (2013) with Mediterranean Pinus halepensis which relied on deeper moisture sources, (depleted δ 18 O cell ), during drought conditions. To reliably interpret highly resolved δ 18 O cell values in relation to water sources requires a clear isotopic characterization of local and regional sources of water (e.g.…”

mentioning

confidence: 99%

“…We believe that such methods could be further enhanced through the incorporation of a dual isotope approach, utilizing δ 13 C to uncover the historical physiological responses of riparian trees to changes in source water availability (e.g. Sarris et al, 2013). Furthermore, we posit that trends in channel morphology (Slater and Singer, 2013;Slater et al, 2015), as well as within site heterogeneity in hydro-geomorphic characteristics may prove to be important controls on the seasonal availability of water sources for tree growth (Singer et al, 2014), which should be a focus of future research.…”

mentioning

confidence: 99%

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Sub‐annual variability in historical water source use by Mediterranean riparian trees

Sargeant

Singer

2016

Ecohydrology

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The seasonal availability of water within a tree's rooting zone may be an important determinant for individual tree growth and overall forest health, particularly in riparian corridors of Mediterranean climate zones that are vulnerable to water stress. Here, we present a new method that combines dendro-isotopes and isotope modelling for determining how water source use varies over 10 consecutive growing seasons (2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010) for co-occurring species Populus nigra and Fraxinus excelsior, along the Rhône River, south-eastern France. We conducted highly resolved δ 18 O analysis of cellulose micro-slices within tree-rings and back-calculated the δ 18 O signature of source water available at the time of growth using a biochemical fractionation model. We related these patterns to inferred seasonal hydrological partitioning through comparison with δ 18 O of waters from the vadose and phreatic zones, precipitation and streamflow. The shallowly rooted Fraxinus displayed greater sub-annual source water variability, as well as greater isotopic enrichment, reflecting use of precipitation-derived vadose moisture. Its earlywood was formed mainly from winter rainfall (δ 18 O depleted) whilst the latewood was composed from growing season precipitation (δ 18 O enriched). In Populus, the sub-annual source water use was relatively depleted, suggesting use of hyporheic water and regional groundwater. From 2007, both species converged in their pattern of water source uptake which was attributed to a decline in phreatic water access for Populus. These results demonstrate that the seasonal variability in source water use can be identified retrospectively, a method which may prove important for anticipating the future consequences of climate-driven changes to the hydrological cycle.

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“…S1). This warming increases water evaporation and causes 18 O enrichment of water at the soil surface that is then archived in the tree-ring isotopic signature (Sarris et al, 2013). The second explanation relates to the increased soil water availability at the HT plot, where trees can use more accessible, shallower water sources that are relatively more 18 O enriched.…”

mentioning

confidence: 99%

Improvement of water and light availability after thinning at a xeric site: which matters more? A dual isotope approach

et al. 2015

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SummaryThinning fosters individual tree growth by increasing the availability of water, light and nutrients. At sites where water rather than light is limiting, thinning also enhances soil evaporation and might not be beneficial. Detailed knowledge of the short-to long-term physiological response underlying the growth responses to thinning is crucial for the management of forests already suffering from recurrent drought-induced dieback.We applied a dual isotope approach together with mechanistic isotope models to study the physiological processes underlying long-term growth enhancement of heavily thinned Pinus sylvestris in a xeric forest in Switzerland. This approach allowed us to identify and disentangle thinning-induced changes in stomatal conductance and assimilation rate.At our xeric study site, the increase in stomatal conductance far outweighed the increase in assimilation, implying that growth release in heavily thinned trees is primarily driven by enhanced water availability rather than increased light availability.We conclude that in forests with relatively isohydric species (drought avoiders) that are growing close to their physiological limits, thinning is recommended to maintain a less negative water balance and thus foster tree growth, and ultimately the survival of forest trees under drought.

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Inter- and intra-annual stable carbon and oxygen isotope signals in response to drought in Mediterranean pines

Cited by 141 publications

References 49 publications

Carbon isotope discrimination and differential drought tolerance in eucalypt clones

Carbon isotope discrimination and differential drought tolerance in eucalypt clones

Sub‐annual variability in historical water source use by Mediterranean riparian trees

Improvement of water and light availability after thinning at a xeric site: which matters more? A dual isotope approach

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