Academic literature on the topic 'Pin d'Orégon – Effets de la sécheresse'
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Journal articles on the topic "Pin d'Orégon – Effets de la sécheresse":
Moos, Christine, and Roland Métral. "La sécheresse croissante met-elle en danger l’effet protecteur de la forêt?" Schweizerische Zeitschrift fur Forstwesen 173, no. 4 (July 1, 2022): 178–83. http://dx.doi.org/10.3188/szf.2022.0178.
Dissertations / Theses on the topic "Pin d'Orégon – Effets de la sécheresse":
Sergent, Anne-Sophie. "Diversité de la réponse au déficit hydrique et vulnérabilité au dépérissement du douglas." Thesis, Orléans, 2011. http://www.theses.fr/2011ORLE2071.
With more than 400 000 ha, Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) is one of the most widely planted species in France. This introduced species native of western North America, is forest managers appreciated for its rapid growth and quality of its wood. However, its productivity performance could be compromised in the context of increased frequency of droughts. Following the exceptional drought of 2003, Douglas has indeed experienced major and durable shortcomings (mortality, leaf loss, reduced growth ...) marking the entry into a phase of decline. The objectives of this work are (1) to check if the hazard inducing decline is drought, (2) to determine the ecological and silvicultural factors of vulnerability to drought and (3) contribute to the exploration of the variability genetic response to drought through the study of provenances from the natural range. Analysis of reports of the Department of Health Forest showed that the two main areas affected by the dieback are post 2003 Burgundy and northeast of the Midi-Pyrenees. The dendro-ecological study conducted in these two regions allowed us to demonstrate (1) the high sensitivity of radial growth in the intensity of soil moisture deficit, (2) if the exceptional drought of 2003 is the decline inducing hazard, recurrent droughts between 2003 and 2006 induced a prolonged loss of radial growth, (3) that soils with low reserves are a factor of vulnerability to dieback. Mineral soil fertility assessed by bio-indication appears as a key factor in the recovery of growth. In the genetic study, no difference in growth in response to drought could be demonstrated between Washington and Oregon provenances. All these results allow us to make recommendations to managers to reduce the risk of dieback induced by drought
Ruiz, diaz britez Manuela. "Adaptation du douglas (Pseudotsuga menziesii (MIRB.) FRANCO) aux changements climatiques : étude rétrospective basée sur l’analyse des cernes." Thesis, Paris, Institut agronomique, vétérinaire et forestier de France, 2016. http://www.theses.fr/2016IAVF0011/document.
Forest response to the drought increase associated to the climatic warming relies on tree adaptive potential, i.e. the genetic variation and the heritability of adaptive traits involved in resistance to drought. In the first chapter, we identify easy-to-measure proxies of adaptive traits for resistance to drought. We compare the wood microdensity of dead and surviving trees after the 2003 heat wave in France. The most discriminating variables are the mean density of high and lowdensity segments, high-density proportion and coefficient of variation of the lowdensity segment. The wood of the surviving trees is always denser and more heterogeneous. If these adaptive traits are variable and heritable, then it is possible to select for improved resistance to drought in the breeding population as well as in natural regeneration. Our results also suggest that directional selection is going on in more or less water-stressed environments. The direction is variable according to the nature of the selection pressure in the different regions. In the Chapter II, we estimate the evolutionary potential to drought of the introduced Douglas-fir in France. This evolutionary potential relies on the magnitude of the genetic variation and of the heritability of the adaptive traits found in the first chapter. The heritability and the genetic variation are highly variable between provenances, sites and, to a much lower extent, between annual rings. Most variables have moderate to high heritability estimates for at least some provenances in some sites. Some traits tend to have generally higher heritability and genetic variation estimates. These are mostly variables of the density part of the annual ring. The variables having at the same time relatively high estimates of heritability and genetic variation are good candidates for becoming efficient selection traits for resistance to drought in tree breeding as well as in natural regeneration. The significant between-site variation suggests that the heritability estimates increase with site quality. The estimates are also significantly different between provenances with a strong provenance × site interaction. Conversely there is little significant between annual-ring variation. The chapter III takes advantage of the annual-ring variation to study the relationships between the genetic parameter estimates and climatic and soil variables. The heritability and genetic variation estimates of most variables significantly relates with most tested environmental variables. Very few variables never correlates with any environmental variable. The significant relationships are very variable between traits, provenances and sites. The most important predictors are temperature, evapotranspiration, and soil water reserve and water deficit. Rainfall marginally influences the genetic parameter estimates. Generally, the better the growing conditions, the higher the estimates. All components of the experimental trials affect the genetic parameters estimates. Thus, the choice of the plant material and of the experimental site strongly determines the genetic parameter estimates. The uncontrolled climatic variation may randomly affect the estimates
Van, Rooij Mahaut. "Etude du rougissement hivernal du Douglas : entre températures douces & formation de glace." Electronic Thesis or Diss., Université Clermont Auvergne (2021-...), 2023. http://www.theses.fr/2023UCFA0154.
The Douglas fir is the first reforestation species in the Auvergne-Rhône-Alpes region and the second in France as a whole, and is of considerable economic importance in France, where 13 million trees are produced each year. Winter reddening affects young Douglas-fir (< 15 years old), affecting up to 80% of the plantation. A reddening tree has no silvicultural future and typically dies within a year after reddening. The objectives of my PhD thesis were to have a better understanding of winter reddening by identifying the climatic parameters that trigger reddening and, more importantly, the physiological mechanism(s) that cause needle reddening.A thorough literature review and bioclimatic analysis were undertaken to identify critical climatic factors. The literature synthesis identified certain climatic conditions characteristic of 'reddening' years, including anticyclonic periods after winter and/or alternating cold and warm periods. Both the literature synthesis and the bioclimatic analysis identified a combination of climatic variables: warm daily temperatures, high daily temperature amplitude, at least moderate wind speeds and relative humidity. However, the freeze-thaw cycles with cold night temperatures did not emerge from the climate analysis, although they are mentioned in the literature.In order to understand how Douglas fir reddens, we first identified gaps in our knowledge of winter reddening and proposed potential mechanisms, either single or interacting, that cause this physiological disorder: 1) winter drought leading to hydraulic failure, 2) photo-oxidative stress, and 3) premature deacclimation. Under controlled conditions, young Douglas fir trees were exposed to winter drought through a temperature differential between roots and canopy (TSOIL < 5°C; TMOY_AIR ~ 14°C). Some of these trees were exposed to light intensities that could induce photooxydative stress (> 1800 PPFD). Cold soil temperatures induced moderate water stress by limiting root water uptake, while warm air temperatures caused water loss at the needle level. However, Douglas fir was able to acclimate to this new environment and even resumed growth. Exposure to high light intensity did not cause irreversible damage to PSII or photooxydative stress. No reddening of the Douglas fir was observed, thus refuting hypothesis 2, but partially supporting hypothesis 1, as the canopy was not exposed to freezing stress. In the field, continuous measurements of young Douglas fir diameter variation were coupled with temperature/humidity measurements from four plots in the Massif Central from December 2020 to June 2023. Spring frosts in April 2021 on deacclimated Douglas fir did not result in needle reddening or cambial damages, thus failing to validate hypothesis 3. Nevertheless, comparison of a asymptomatic winter (2021) with a asymptomatic winter i.e. with winter reddening (2022) revealed significant hydraulic stress generated from the apex, associated with an anticyclone period in January 2022. Hydraulic failure could be exacerbated by daily transpiration, combined with freeze-thaw cycles that increase hydraulic stress, leading to canopy hydraulic failure that could explain needle desiccation and reddening. We therefore favour hypothesis 1, which should be tested under controlled conditions
Dubos, Christian. "Réponse moléculaire de jeunes plants de pin maritime soumis à un stress hydrique en milieu hydroponique." Nancy 1, 2001. http://docnum.univ-lorraine.fr/public/SCD_T_2001_0183_DUBOS.pdf.
Drought greatly affects the growth and development of plants. For long lived woody species, water deprivation should be considered not only in the short-term, i. E. Summer drought, but also in the long-term because of the inflence of global warming. Such climatic modifications will coincide with the time lag required to achieve a breeding cycle. The maintenance of sufficient growth under stress conditions will therefore require the availability of varieties or natural resources that are adapted to present and future climatic conditions, if major losses are to be avoided. Our study is in keeping with an interdisciplinary program for the identification of phenotypic and molecular selection criteria. This thesis focuses on the molecular mechanisms involved in water-deficit response, of young seedlings growing in a hydropononic medium. An expression study carried out at the transcriptome level was developed using mRNA extracted from control and stress conditions for both the aerial part and the roots. This approach was completed by the analysis of protein accumulation
Podor, Myriam. "Effets de la sécheresse et de l'ozone sur le statut hydrique et la gestion du carbone chez le pin d'Alep (Pinus halepensis Mill. )." Vandoeuvre-les-Nancy, INPL, 1997. http://www.theses.fr/1997INPL040N.
Bogeat-Triboulot, Marie-Béatrice. "Effets du stress osmotique et de la carence en potassium sur la croissance racinaire du pin maritime : étude biomécanique du grandissement cellulaire." Nancy 1, 1996. http://docnum.univ-lorraine.fr/public/SCD_T_1996_0019_TRIBOULOT.pdf.
This work allowed us to improve our knowledge about the control of root growth of maritime pine. This study, which is based on a biophysical analysis of cell expansion, utilised two new microtechnologies: the cell pressure probe and the picolitre osmometer. In unstressed plants, cell turgor pressure was uniform over the entire elongation zone. On the other hand, cell wall rheological properties changed during cell maturation and controlled cell expansion. Three levels of osmotic stress affected root growth differently. A moderate water deficit stimulated root growth by increasing cell wall extensibility, in spite of a small decrease of cell turgor pressure. During the medium water deficit, a reduction of cell turgor pressure was compensated by an increase of cell wall extensibility, root growth rate was not affected. During the highest water deficit, root growth was inhibited by a strong reduction of turgor pressure. The root system responded heterogeneously to a potassium shortage. Tap root growth was not modified by this constraint: neither turgor pressure nor rheological properties were affected. On the other hand, lateral roots growth was strongly inhibited by a reduction of cell wall extensibility. Moreover, in the apex of the tap root, a small reduction in potassium concentration (divided by 2), and also of other inorganic ions, was completely compensated by an increase of soluble sugars and glutamine concentrations. In the apex of lateraI roots, a large reduction in potassium concentration (divided by 8), and of other inorganic ions, was practically not compensated, inducing a reduction of the osmotic pressure in mature tissues
Lu, Ping. "Ecophysiologie et réaction à la sécheresse de trois espèces de conifères (Abies alba Miller, Picea abies (L. ) Karsten et Pinus sylvestrisS L. ) : effet de l'âge." Nancy 1, 1992. http://www.theses.fr/1992NAN10339.
Water relations and gas exchange of 3 conifer species (seedlings, saplings and adult trees) were examined under controlled and/or natural conditions. Under controlled conditions, measurement on 9 month old seedlings showed that Abies alba had weak stomatal control when subjected to soil drought, while Pinus sylvestris and Picea abies exhibited a stronger stomatal sensitivity to drought. For 5-6 year old saplings, differences between these species were not significant. The passage from seedling stage to sapling stage increased the gas exchange rate for Picea abies and Pinus sylvestris, the inverse was found for Abies alba. Water transfer in the trees was assessed in an adult stand of Picea abies in the Vosges (NE France). Transpiration fell from 60% to 10% of Penman’s evapotranspiration while the predawn water potential decreased from -0. 5 to -1. 0 MPa. Whole-tree hydraulic conductance calculated from diurnal sap flow and twig water potential measurements also showed an important decrease during this dry period. Partitioning of whole-tree hydraulic conductance and measurement of xylem embolism in the twigs showed that the major modification of water movement in the soil-leaves pathway was at the soil-root interface. No embolism was detected for these trees in spite of a severe drought
Picon-Cochard, Catherine. "Effets combinés d'un doublement de la concentration en C02 de l'air et de sécheresses édaphiques sur la croissance et l'efficience d'utilisation de l'eau de Quercus petraea, Quercus robur et Pinus pinaster." Nancy 1, 1996. http://www.theses.fr/1996NAN10076.
Fort, Christine. "Régulation des échanges hydriques de jeunes plants de différentes espèces forestières feuillues et résineuses : effet de la contrainte hydrique, rôle du substrat et origine de la régulation stomatique." Nancy 1, 1997. http://www.theses.fr/1997NAN10262.
This work had as first objective the analysis of growth and water relations of three forest species (Quercus petraea, Pinus pinaster and Betula pendula), in relation with soil type, under optimal and water stress conditions. Clear differences were observed between species. In absence of water stress, birch presented the greatest plasticity with respect to soil type. It is also characterised by higher values of stomatal conductance and hydraulic conductance than the two other species. It's stomatal regulation under water stress is belated and has only been evidenced for very lower values of soil water content (3%). In parallel, strong leaf shedding has been observed. No interaction related to the nature of substrate has been observed. A second aim was to tested, under water stress conditions, the impact of root-sourced abscisic acid (ABA) in stomatal regulation. The existence of such root signalling, based only on root ABA has not been confirmed and this, on the three forest species studied (Quercus robur, Pinus pinaster and Betula pendula). The stomatal regulatory mechanisms are certainly more complex and probably implicate a double mechanism, foliar and root mediating
Pelloux, Jérôme. "Contribution à l'étude des effets de l'ozone, de la sécheresse et du stress salin sur le métabolisme carboné du pin d'Alep (Pinus halepensis Mill. ). Régulation de la rubisco et de la rubisco activase." Nancy 1, 2000. http://www.theses.fr/2000NAN10086.
The decline of aleppo pine forests (Pinus halepensis M. ) observed in natural conditions have prompted research concerning the effects of abiotic stresses on this species. For this purpose, the effects of ozone, water stress and salt stress on aleppo pine's carbon metabolism were carried out in this study. Ozone did induce chlorotic mottles, linked to a decrease in chlorophyll content. A decline in total rubiseo activity, and an increase in the activities of several enzymes associated to the catabolic pathway such as pyruvate kinase (PK), phosphoenolpyruvate carboxylase (PEPc) and malic enzymes (EM-NAD and EM-NADP) were shown in needles of pines submitted to ozone. These results tend to show that an increase in compounds potentially used in detoxifying repair processes is occuring under ozone stress. Water and salt stresses would limit the deleterious effects of ozone on plant metabolism, presumably by inducing stomatal closure which would limit the pollutant input into the leaves. Studies on the regulation of rubisco and rubisco aetivase, were undertaken at a molecular level in needles of pines submitted to ozone and/or drought. For this purpose, the cloning of cDNA fragments coding for rubisco large subunit (LSU) and for rubisco activase (RCA) was realized, allowing a phylogenetic analysis of both proteins. A decrease of LSU and RCA protein quantities, associated to a transcriptional regulation, was shown in response to ozone,> suggesting a potential coregulation of both proteins in those particular conditions. Even though the effects of drought on the large subunit of rubisco and on rubisco activase were similar, no correlation between the effects of this stress on the two proteins could be drawn. When ozone was combined to drought, a difference in the regulation of rubisco large subunit and of rubisco activase was shown. Under those conditions, rubisco large subunit was under a transcriptional control whereas rubisco activase was under a post transcriptionnal regulation. For the very first time in this study, a conifer' s rubisco activase is partially cloned and its regulation studied in reponse to abiotic constraints