Recent economic and social changes in north Mediterranean regions have led to an important rural ... more Recent economic and social changes in north Mediterranean regions have led to an important rural depopulation. Consequently, meadows developed on abandoned agricultural lands (characterized by high species richness) undergo reforestation. These former fields are mainly colonized by Pinus halepensis Miller, which is known to synthetize a wide range of secondary metabolites, among these, some could influence plant succession through allelopathy. The allelopathic potential of P. halepensis, was tested against two target species (Lactuca sativa L. and Linum strictum L.) with aqueous extracts obtained from different organs (root and needle) taking into account the individual age (±10, ±30 and >60 years old). Root and needle extracts affected differently germination and growth of the two target species, the responses varying with concentration of extracts, age and organs tested. The strongest inhibitory effect was observed on the germination and growth of L. strictum, exposed to needle extracts of young P. halepensis (±10 years old), and root extracts of older P. halepensis (>30 years old). These extracts contained several phenolic acids (e.g. 4-hydroxybenzoic acid and p-coumaric acid), which are known as allelochemicals and their concentrations vary with age and organ tested. Hence, P. halepensis could influence secondary succession through the release of potential allelochemicals in the environment by leaf leachates or root exudates.
Growth trends observed on trees are interpreted as the result of global changes. Among them 13 cl... more Growth trends observed on trees are interpreted as the result of global changes. Among them 13 climate change with exceptional climatic events is becoming a major issue. In the present study, 14 we focused on the largest Scots pine forest situated near Marseille, on the North side of the 15 Sainte-Baume mountain range. We present some results of a study aiming at assessing the impact 16 of the exceptional drought and heat wave of 2003 on health status and the growth of Scots pine. 17
SUMMARY - This paper deals with the impact of climate change on the productivity of Pinus halepen... more SUMMARY - This paper deals with the impact of climate change on the productivity of Pinus halepensis and Pinus silvestris in the French Mediterranean area and the shift of the bioclimatic limit between theses two pines. It also gives some of the main synthetic results of this research, based mainly on dendroecology. The experimental design includes a series of plots distributed along an altitudinal transect on the north slope of Sainte-Baume mountain. The choice of the site, homogeneous for rainfall regime, as well as the homogeneity in substrata, soil and topography at the level of plots, allows to focus on the variations of the response of trees due to differences in mean annual temperatures. Additional plots with soils much deeper or much shallower than those of the main transect also allow studying the interaction between climate and soil water balance on the growth of trees. The impact of the exceptional scorching heat and drought of year 2003 is also analyzed. The response of ...
Mediterran ean area. In : Leone V. (ed.), Lovreglio R. (ed.). Proceedings of the international wo... more Mediterran ean area. In : Leone V. (ed.), Lovreglio R. (ed.). Proceedings of the international workshop MEDPINE 3: conservation, regeneration and restoration of Mediterranean pines and their ecosystems.
Le changement climatique a des effets à long terme en raison de la dérive de ses paramètres moyen... more Le changement climatique a des effets à long terme en raison de la dérive de ses paramètres moyens : élévation de la température, réduction des pluies de printemps ou d'été. Mais le climat a aussi un impact fort lorsque des conditions extrêmes dépassent les seuils supportables par certaines espèces : c'est le cas des canicules comme celle de l'année 2003 ou, en Provence, de la répétition exceptionnelle des sécheresses entre 2003 et 2008. On observe entre 1996 et 2008 une modification sensible de la composition floristique des forêts. Les plantes les plus exigeantes en eau et en fraîcheur ont beaucoup perdu de terrain, tandis que les plus résistantes à la sécheresse gagnaient en surface comme en abondance. La productivité et la croissance en hauteur des arbres méditerranéens comme le pin d'Alep ont progressé de 40% durant le 20ème siècle, tandis que celle des espèces plus nordiques et montagnardes comme le pin sylvestre perdait au moins autant. En raison de la répétit...
Les deux auteurs, l'un astronome l'autre botaniste (et chargé de mission patrimoine de l&... more Les deux auteurs, l'un astronome l'autre botaniste (et chargé de mission patrimoine de l'université d'Aix-Marseille), présentent quelques idées sur la gestion des collections historiques d'astronomie, dans un contexte universitaire. Nous mettons en avant la spécificité de ces collections par rapport à celles des musées traditionnels et leur importance pour l'histoire des sciences notamment. Nous rappelons également la nécessité de suivre la déontologie muséale soutenue par l'association Universeum, réseau européen pour le patrimoine universitaire. Enfin nous rappelons le rôle essentiel que jouent les réserves et la nécessité de travailler en collaboration.
Failure of seed production in the genus Arundo L. (Poaceae) is often attributed to polyploidy. Th... more Failure of seed production in the genus Arundo L. (Poaceae) is often attributed to polyploidy. This study tested the impact of two ploidy levels (2n=12 and 18x) on the fertility of four Mediterranean Arundo. Viable pollen was screened from its production to its germination, and seed occurrence was monitored in admixture or isolated conditions. In addition, insights on restructuration of polyploid genomes were analysed using molecular cytogenetics. Our results show that high ploidy levels do not automatically induce failure of sexual reproduction. The two ploidy levels are able to produce viable pollen and seed set depending on species and cultural conditions. The sterility of A. micrantha (2n=12x) and A. donax (2n=18x) is due to the early failures of gametogenesis steps. For 18x cytotypes of A. donaciformis and A. plinii, seed absence for isolated genotype vs. seed production in admixed culture support their auto-incompatibility.
Comptes rendus de l'Académie des sciences. Série III, Sciences de la vie, 2000
The climatic impact on tree radial growth resulting from an atmospheric CO2 doubling was studied ... more The climatic impact on tree radial growth resulting from an atmospheric CO2 doubling was studied for 24 populations of five tree species in the French Alps and the French Mediterranean area. The Arpege AGCM, which predicts a 3 degrees C increase in mean temperature and a light increase of precipitation, is used to estimate the climatic perturbation. The method is based on the integration of estimated climate in an empirical tree-ring to climate model, involving artificial neural networks. Only a few populations are sensitive to the climatic change; all are located on the boundaries of their ecological area and can be divided in two groups. The first one is composed of high altitude populations which show a growth increase induced by the warmer climate during the growing season. The second one, composed of a single Mediterranean Scots pine population, reacts with a severe growth reduction induced by the stronger water stress in summer.
Aim Although recognized as hotspots of biodiversity, Mediterranean peninsulas have been poorly st... more Aim Although recognized as hotspots of biodiversity, Mediterranean peninsulas have been poorly studied with regard to the evolutionary legacy of Quaternary environmental changes for endemic lowland biota. Using the phylogeography of the lowland Arundo plinii Turra (Poaceae), we evaluated two hypotheses regarding the genetic structure of southern European species, that there is: (H 1 ) a decrease in regional genetic diversity with increasing latitude induced by past contractions towards southern refugia; and (H 2 ) a strong differentiation between isolated refugia without a latitudinal gradient in genetic diversity.
Recent economic and social changes in north Mediterranean regions have led to an important rural ... more Recent economic and social changes in north Mediterranean regions have led to an important rural depopulation. Consequently, meadows developed on abandoned agricultural lands (characterized by high species richness) undergo reforestation. These former fields are mainly colonized by Pinus halepensis Miller, which is known to synthetize a wide range of secondary metabolites, among these, some could influence plant succession through allelopathy. The allelopathic potential of P. halepensis, was tested against two target species (Lactuca sativa L. and Linum strictum L.) with aqueous extracts obtained from different organs (root and needle) taking into account the individual age (±10, ±30 and >60 years old). Root and needle extracts affected differently germination and growth of the two target species, the responses varying with concentration of extracts, age and organs tested. The strongest inhibitory effect was observed on the germination and growth of L. strictum, exposed to needle extracts of young P. halepensis (±10 years old), and root extracts of older P. halepensis (>30 years old). These extracts contained several phenolic acids (e.g. 4-hydroxybenzoic acid and p-coumaric acid), which are known as allelochemicals and their concentrations vary with age and organ tested. Hence, P. halepensis could influence secondary succession through the release of potential allelochemicals in the environment by leaf leachates or root exudates.
Growth trends observed on trees are interpreted as the result of global changes. Among them 13 cl... more Growth trends observed on trees are interpreted as the result of global changes. Among them 13 climate change with exceptional climatic events is becoming a major issue. In the present study, 14 we focused on the largest Scots pine forest situated near Marseille, on the North side of the 15 Sainte-Baume mountain range. We present some results of a study aiming at assessing the impact 16 of the exceptional drought and heat wave of 2003 on health status and the growth of Scots pine. 17
SUMMARY - This paper deals with the impact of climate change on the productivity of Pinus halepen... more SUMMARY - This paper deals with the impact of climate change on the productivity of Pinus halepensis and Pinus silvestris in the French Mediterranean area and the shift of the bioclimatic limit between theses two pines. It also gives some of the main synthetic results of this research, based mainly on dendroecology. The experimental design includes a series of plots distributed along an altitudinal transect on the north slope of Sainte-Baume mountain. The choice of the site, homogeneous for rainfall regime, as well as the homogeneity in substrata, soil and topography at the level of plots, allows to focus on the variations of the response of trees due to differences in mean annual temperatures. Additional plots with soils much deeper or much shallower than those of the main transect also allow studying the interaction between climate and soil water balance on the growth of trees. The impact of the exceptional scorching heat and drought of year 2003 is also analyzed. The response of ...
Mediterran ean area. In : Leone V. (ed.), Lovreglio R. (ed.). Proceedings of the international wo... more Mediterran ean area. In : Leone V. (ed.), Lovreglio R. (ed.). Proceedings of the international workshop MEDPINE 3: conservation, regeneration and restoration of Mediterranean pines and their ecosystems.
Le changement climatique a des effets à long terme en raison de la dérive de ses paramètres moyen... more Le changement climatique a des effets à long terme en raison de la dérive de ses paramètres moyens : élévation de la température, réduction des pluies de printemps ou d'été. Mais le climat a aussi un impact fort lorsque des conditions extrêmes dépassent les seuils supportables par certaines espèces : c'est le cas des canicules comme celle de l'année 2003 ou, en Provence, de la répétition exceptionnelle des sécheresses entre 2003 et 2008. On observe entre 1996 et 2008 une modification sensible de la composition floristique des forêts. Les plantes les plus exigeantes en eau et en fraîcheur ont beaucoup perdu de terrain, tandis que les plus résistantes à la sécheresse gagnaient en surface comme en abondance. La productivité et la croissance en hauteur des arbres méditerranéens comme le pin d'Alep ont progressé de 40% durant le 20ème siècle, tandis que celle des espèces plus nordiques et montagnardes comme le pin sylvestre perdait au moins autant. En raison de la répétit...
Les deux auteurs, l'un astronome l'autre botaniste (et chargé de mission patrimoine de l&... more Les deux auteurs, l'un astronome l'autre botaniste (et chargé de mission patrimoine de l'université d'Aix-Marseille), présentent quelques idées sur la gestion des collections historiques d'astronomie, dans un contexte universitaire. Nous mettons en avant la spécificité de ces collections par rapport à celles des musées traditionnels et leur importance pour l'histoire des sciences notamment. Nous rappelons également la nécessité de suivre la déontologie muséale soutenue par l'association Universeum, réseau européen pour le patrimoine universitaire. Enfin nous rappelons le rôle essentiel que jouent les réserves et la nécessité de travailler en collaboration.
Failure of seed production in the genus Arundo L. (Poaceae) is often attributed to polyploidy. Th... more Failure of seed production in the genus Arundo L. (Poaceae) is often attributed to polyploidy. This study tested the impact of two ploidy levels (2n=12 and 18x) on the fertility of four Mediterranean Arundo. Viable pollen was screened from its production to its germination, and seed occurrence was monitored in admixture or isolated conditions. In addition, insights on restructuration of polyploid genomes were analysed using molecular cytogenetics. Our results show that high ploidy levels do not automatically induce failure of sexual reproduction. The two ploidy levels are able to produce viable pollen and seed set depending on species and cultural conditions. The sterility of A. micrantha (2n=12x) and A. donax (2n=18x) is due to the early failures of gametogenesis steps. For 18x cytotypes of A. donaciformis and A. plinii, seed absence for isolated genotype vs. seed production in admixed culture support their auto-incompatibility.
Comptes rendus de l'Académie des sciences. Série III, Sciences de la vie, 2000
The climatic impact on tree radial growth resulting from an atmospheric CO2 doubling was studied ... more The climatic impact on tree radial growth resulting from an atmospheric CO2 doubling was studied for 24 populations of five tree species in the French Alps and the French Mediterranean area. The Arpege AGCM, which predicts a 3 degrees C increase in mean temperature and a light increase of precipitation, is used to estimate the climatic perturbation. The method is based on the integration of estimated climate in an empirical tree-ring to climate model, involving artificial neural networks. Only a few populations are sensitive to the climatic change; all are located on the boundaries of their ecological area and can be divided in two groups. The first one is composed of high altitude populations which show a growth increase induced by the warmer climate during the growing season. The second one, composed of a single Mediterranean Scots pine population, reacts with a severe growth reduction induced by the stronger water stress in summer.
Aim Although recognized as hotspots of biodiversity, Mediterranean peninsulas have been poorly st... more Aim Although recognized as hotspots of biodiversity, Mediterranean peninsulas have been poorly studied with regard to the evolutionary legacy of Quaternary environmental changes for endemic lowland biota. Using the phylogeography of the lowland Arundo plinii Turra (Poaceae), we evaluated two hypotheses regarding the genetic structure of southern European species, that there is: (H 1 ) a decrease in regional genetic diversity with increasing latitude induced by past contractions towards southern refugia; and (H 2 ) a strong differentiation between isolated refugia without a latitudinal gradient in genetic diversity.
Uploads
Papers by Bruno Vila