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Auteur Caroline C Bresson
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Evidence of altitudinal increase in photosynthetic capacity : gas exchange measurements at ambient and constant CO2 partial pressures / Caroline C Bresson in Annals of Forest Science, 66 (2009)
Titre : Evidence of altitudinal increase in photosynthetic capacity : gas exchange measurements at ambient and constant CO2 partial pressures Type de document : Électronique Auteurs : Caroline C Bresson ; AndrewS Kowalski ; Antoine Kremer (1951-) ; Sylvain Delzon (1977-) Année de publication : 2009 Article en page(s) : 8 p. Langues : Anglais (eng) Catégories : [Thématique] Assimilation nette, photosynthèse, métabolisme du carbone, photorespiration, respiration, fermentation (anoxie,hypoxie)
Résumé : Because all microclimatic variables change with elevation, it is difficult to compare plant performance and especially photosynthetic capacity at different elevations. Indeed, most previous studies investigated photosynthetic capacity of low- and high-elevation plants using constant temperature, humidity and light but varying CO2 partial pressures (P CO 2). Using gas exchange measurements, we compared here maximum assimilation rates (A max) at ambient and constant-low-elevation P CO 2for two temperate tree species along an altitudinal gradient (100 to 1600 m) in the Pyrénées mountains. Significant differences in A max were observed between the CO2 partial pressure treatments for elevations above 600 m, the between-treatment differences increasing with elevation up to 4 μmol m−2 s−1. We found an increase in A max with increasing elevation at constant-low-elevation P CO 2 but not at ambient P CO 2 for both species. Given a 10% change in P CO 2, a proportionally higher shift in maximum assimilation rate was found for both species. Our results showed that high elevation populations had higher photosynthetic capacity and therefore demonstrated that trees coped with extreme environmental conditions by a combination of adaptation (genetic evolution) and of acclimation. Our study also highlighted the importance of using constant CO2 partial pressure to assess plant adaptation at different elevations.
Lien pérenne : DOI : 10.1051/forest/2009027
in Annals of Forest Science > 66 (2009) . - 8 p.Bresson, C.C., Kowalski, A., Kremer, A., Delzon, S. 2009. Evidence of altitudinal increase in photosynthetic capacity : gas exchange measurements at ambient and constant CO2 partial pressures. Annals of Forest Science, 66: 8 p..
Quantifying phenological plasticity to temperature in two temperate tree species / Yann Vitasse in Functional Ecology, (2010)
Titre : Quantifying phenological plasticity to temperature in two temperate tree species Type de document : Électronique Auteurs : Yann Vitasse (1981-) ; Caroline C Bresson ; Antoine Kremer (1951-) ; Richard Michalet ; Sylvain Delzon (1977-) Année de publication : 2010 Article en page(s) : 10.1111/j.1365-2435.2010.01748.x Langues : Anglais (eng) Catégories : [Thématique] Phénologie
[Thématique] Rôle de la températur en physiologie végétale
1. Phenotypic plasticity allows large shifts in the timing of phenology within one single generation and drives phenotypic variability under environmental changes, thus it will enhance the inherent adaptive capacities of plants against future changes of climate.
2. Using five common gardens set along an altitudinal gradient (100–1600 m asl.), we experimentally examined the phenotypic plasticity of leaf phenology in response to temperature increase for two temperate tree species (Fagus sylvatica and Quercus petraea). We used seedlings from three populations of each species inhabiting different altitudes (400, 800 and 1200 m asl.). Leaf unfolding in spring and leaf senescence in autumn were monitored on seedlings for 2 years.
3. Overall, a high phenological plasticity was found for both species. The reaction norms of leaf unfolding date to temperature linearly accelerated for both species with an average shift of −5·7 days per degree increase. Timing of leaf senescence exhibited hyperbolic trends for beech due to earlier senescence at the lowest elevation garden and no or slight trends for oak. There was no difference in the magnitude of phenological plasticity among populations from different elevations. For both species, the growing season length increased to reach maximum values at about 10–13 °C of annual temperature according to the population.
4. Since the magnitude of phenological plasticity is high for all the tested populations, they are likely to respond immediately to temperature variations in terms of leaf phenology. Consequently the mid- to high-elevation populations are likely to experience a longer growing season with climate warming. The results suggest that climate warming could lengthen the growing season of all populations over the altitudinal gradient, although the low-elevation populations, especially of beech, may experience accelerated senescence and shorter growing season due to drought and other climate changes associated with warming.
Lien pérenne : DOI : 10.1111/j.1365-2435.2010.01748.x
in Functional Ecology > (2010) . - 10.1111/j.1365-2435.2010.01748.xVitasse, Y., Bresson, C.C., Kremer, A., Michalet, R., Delzon, S. 2010. Quantifying phenological plasticity to temperature in two temperate tree species. Functional Ecology: 10.1111/j.1365-2435.2010.01748.x.
To what extent is altitudinal variation of functional traits driven by genetic adaptation in European oak and beech ? / Caroline C Bresson in Tree pysiology, 31 (11) (November 2011)
Titre : To what extent is altitudinal variation of functional traits driven by genetic adaptation in European oak and beech ? Type de document : Électronique Auteurs : Caroline C Bresson ; Yann Vitasse (1981-) ; Antoine Kremer (1951-) ; Sylvain Delzon (1977-) Année de publication : 2011 Article en page(s) : 1164-1174 Langues : Anglais (eng) Catégories : [Thématique] Adaptation au milieu
[Thématique] Adaptation au milieu et aux conditions de culture
[Thématique] Adaptation naturelle au climat, résistance
Mots-clés : Quercus L., 1753 Fagus L., 1753 Résumé : The phenotypic responses of functional traits in natural populations are driven by genetic diversity and phenotypic plasticity. These two mechanisms enable trees to cope with rapid climate change. We studied two European temperate tree species (sessile oak and European beech), focusing on (i) in situ variations of leaf functional traits (morphological and physiological) along two altitudinal gradients and (ii) the extent to which these variations were under environmental and/or genetic control using a common garden experiment. For all traits, altitudinal trends tended to be highly consistent between species and transects. For both species, leaf mass per area displayed a positive linear correlation with altitude, whereas leaf size was negatively correlated with altitude. We also observed a significant increase in leaf physiological performance with increasing altitude: populations at high altitudes had higher maximum rates of assimilation, stomatal conductance and leaf nitrogen content than those at low altitudes. In the common garden experiment, genetic differentiation between populations accounted for 0-28% of total phenotypic variation. However, only two traits (leaf mass per area and nitrogen content) exhibited a significant cline. The combination of in situ and common garden experiments used here made it possible to demonstrate, for both species, a weaker effect of genetic variation than of variations in natural conditions, suggesting a strong effect of the environment on leaf functional traits. Finally, we demonstrated that intrapopulation variability was systematically higher than interpopulation variability, whatever the functional trait considered, indicating a high potential capacity to adapt to climate change. Lien pérenne : DOI : 10.1093/treephys/tpr084
in Tree pysiology > 31 (11) (November 2011) . - 1164-1174Bresson, C.C., Vitasse, Y., Kremer, A., Delzon, S. 2011. To what extent is altitudinal variation of functional traits driven by genetic adaptation in European oak and beech ? Tree pysiology, 31(11): 1164-1174.