The earliest embryonic stages, because of the simplicity of their organization and cellular structure, are logical starting points for developmental studies of plants as a whole. The zygote and early post-zygote phases of embryonic development are periods of minimum cell form differentiation, if the cells possess a potentially to develop in a number of different ways at any stages in their development, it is in all likelihood at this early date. Becoming more and more specialized with continued growth, they finally form tissues and organs with the capacity for specific functions in the division of labour of the mature plant organization. it was felt that the more specialized the cells became, the less impressionable they would be to the influence of an in-vitro environment. Accordingly, this treatise deals with the culture in artificial medium of the early post-fertilization periods in the embryonic growth of Pinus nigra, var. austriaca, in an effort to discover and assess those factors which influence and govern the embryonic development pattern. The present study was begun in 1951 at the suggestion of Professor N.W. Radforth. I wish to express my appreciation to Professor Radforth for his guidance in conducting my research, without which this investigation could not have been carried out. This work was undertaken as part of a programme which has been assisted through a grant from the Ontario Cancer Treatment and Research Foundation, for which Dr. Radforth is the grantee. / Thesis / Master of Science (MS)

Little is known about funda­mental mechanisms of growth control on the growth ff single or small groups of cells of the higher plants. Study of these effects in vitro requires the knowledge of the primary conditions for growth in vitro. In this work a procedure was outlined and used in an ef­fort to establish a basis for the standard procedure. Also the associated effects of the physical, and to some extent, the chemical environment on the growth of the proembryo and prothallium. of Linus were studied. / Thesis / Master of Science (MS)

El fuego constituye un elemento clave en la configuración del paisaje mediterráneo. Sin embargo, desde hace unos treinta años, se vienen registrando importantes incrementos en la frecuencia, intensidad y dimensiones máximas alcanzadas por los incendios en este ámbito bioclimático, por lo que la regeneración postincendio actual de muchas de sus masas boscosas resulta dificultosa. Para algunas especies llega a suponer, incluso, una reducción importante de su área de distribución. Este es el caso del Pinus nigra en Cataluña, cuya distribución se ha visto reducida recientemente en un 30% por los dos mayores incendios registrados hasta la fecha en esta comunidad (1994 y 1998). Pinus nigra es una especie germinadora, que dispersa durante el invierno y cuyas semillas perduran poco tiempo, por lo que su reclutamiento depende cada año de nueva producción. Sin embargo, en incendios muy grandes, todo el plantío joven es devastado y la supervivencia de árboles es generalmente muy baja.En esta tesis hemos tratado de recabar el máximo de información empírica posible sobre cada etapa del reclutamiento de los bosques de Pinus nigra afectados por estos dos incendios y, posteriormente, hemos elaborado con toda esa información un modelo mecanicista que nos permita simular la regeneración más probable a un plazo de tiempo dado.En el primer capítulo evaluamos la supervivencia y la capacidad para producir piñas de los árboles afectados en mayor o menor medida por el fuego durante los tres primeros años posteriores a él. La supervivencia resultó ser mayor en los árboles más grandes y en los menos afectados por fuego de copa. La producción de piñas fue mayor y más frecuente en los árboles grandes y en las "islas verdes" de árboles supervivientes, especialmente las pequeñas. Por ello, destacamos el interés de preservar los árboles mayores supervivientes y las "islas verdes" como probables focos de dispersión que mejoren las posibilidades de regeneración de la especie.En el segundo capítulo exploramos los patrones de variación espacio-temporal de la depredación post-dispersión del banco de semillas del suelo. Los resultados muestran que al inicio del periodo de dispersión, los roedores son los principales depredadores mientras que a partir de la primavera lo son las hormigas, resultando ambos grupos muy eficaces. Teniendo en cuenta la corta viabilidad de los piñones diseminados, esta elevada depredación hace que la probabilidad de que alguna semilla siga disponible para germinar en otoño sea prácticamente nula.El tercer capítulo estudia el establecimiento de las plántulas, mediante un experimento bajo condiciones controladas de luz y agua, y otro bajo diferentes condiciones naturales de campo. Los resultados sugieren que el establecimiento de plántulas tras el incendio es muy escaso en condiciones de campo y bajo un rango amplio de grados de cobertura. A pesar de ello, Pinus nigra se comporta como una especie más tolerante a la sombra que otros pinos, pero, dado que ésta es una condición muy poco frecuente en las áreas recientemente quemadas, su regeneración se ve muy condicionada por los incendios.En el capítulo cuarto, desarrollamos un modelo de simulación que integra toda la información recabada acerca de la biología de la regeneración de esta especie, procendente en parte de los capítulos anteriores. El estudio muestra que es posible calibrar un modelo mecanístico que simule el reclutamiento de una especie arbórea a partir de información empírica obtenida para los distintos procesos, incluso cuando las bases de datos disponibles carezcan de series temporales o espaciales amplias. Las posibilidades de este modelo como herramienta de trabajo son muy valiosas a la hora de tomar decisiones sobre la gestión de las áreas quemadas. / Fire constitutes a key factor in the configuration of Mediterranean landscapes. Nevertheless, from nearly thirty years ago, an important increment in the frequency, intensity and size of fires has been registered in this bioclimatic environment. For this reason, the postfire regeneration of many burned areas may be difficult, representing, for some species, an important reduction of their distribution areas. This is the case of Pinus nigra in Catalonia (NE Spain), whose distribution area has been reduced in 30% due to the two largest wildfires (1994 and 1998) occurred historically in this region. Pinus nigra is a seeder species, which disperses its seeds in winter, but they remain viable for a short period of time. Thus, the recruitment of this species depends on the year-to-year seed production. However, in very large fires, all seedlings and saplings are burned and tree survival is usually very low.In this Ph. D. Thesis, we have compiled the maximum empirical information concerning the different stages of the recruitment process of Pinus nigra in burned areas. Afterwards, we have elaborated a mechanistic model with all this information to simulate the potential regeneration at the mid-term.In the first chapter, we have evaluated tree survival and cone production of burned and unburned trees, during the tree years after fire. Tree survival was higher in the largest and less affected trees. Cone production was higher and more frequent in the large trees, and also in the "green islands" of vegetation, particularly in the small ones. For this reason, we enhance the interest to keep the largest trees and the "green islands" as possible seed dispersal sources, for improving the regeneration of this species. In the second chapter, we explore the spatial and temporal patterns of post dispersal seed predation. The results show that in winter, at the beginning of dispersal period, rodents are the main seed predators, while in spring ants become dominant as seed predators. The two groups are very efficient. Taking in account that seed viability is very short on the ground, this high predation rate makes that the probability of P. nigra seeds to germinate in autumn is almost nil.The third chapter studies the establishment of seedlings, by means of an experiment of controlled conditions of light and water, and another field experiment in natural conditions. The results suggest that seedling establishment after fire is very scarce in natural conditions and in a extensive range of cover degrees. In spite of it, Pinus nigra behaves as a more shade-tolerant species than other pines. However, as this situation is rare in recently burned areas, its regeneration is very conditioned by fires.In the fourth chapter, we develop a simulation model integrating all the information obtained about the regeneration stages of this species, in part obtained in the previous chapters. The study shows that it is possible calibrate a mechanistic model to simulate the recruitment of a tree species, using empirical information obtained for the different processes, even though when the databases available do not always have extensive temporal or spatial series. The possibilities of this model as an interesting tool may be very interesting for the management of burned areas.

L'étude de l'écologie des micro-organismes est récente malgré son importance pratique et théorique intrinsèque mais également son rôle central dans la niche des macro-organismes. Les interactions plantes-champignons, de par leur importance socio-écologique et de leur diversité -- du mutualisme au parasitisme en passant par le commensalisme --, offrent un modèle judicieux pour étudier l'écologie des communautés de micro-organismes en interaction avec des macro-organismes. À l'aide de techniques de séquençage à haut débit (NGS) et d'analyse des réseaux, nous explorons certains déterminants de la structure des champignons des forêts corses à travers trois guildes : les champignons ectomycorhiziens, endophytiques et saprotrophes. Ce travail considère les processus de dispersion, les perturbations (feux et chablis), les facteurs environnementaux (par ex. la profondeur du sol) et les contraintes dérivées de l'interaction avec les hôtes (par ex. taxinomie). Les assemblages des communautés des différentes guildes présentent des patrons communs qui pourraient être issus de mécanismes identiques. Ainsi, l'ensemble des guildes étudiées présentent des variations fortes à l’échelle des micro-régions de Corse et entre forêts ayant des histoires de feux différentes. En revanche, l'importance des différents processus d'assemblage et les échelles spatiales auxquelles ils s'appliquent varient selon les guildes. Nous discutons des implications que suscitent ce travail pour les écologues des communautés et pour les gestionnaires d'espaces naturels. / Study of micro-organisms ecology arose recently despite its intrinsic importance -- both practical and theoretical --, but also despite its overriding role in the niches of macro-organisms. Plant-fungi interactions offer a relevant model to study the ecology of micro-organisms interacting with macro-organisms because of their considerable ecological and economical values in addition to their high taxonomic and ecological diversity. Using next-generation sequencing (NGS) and network analysis, we explore some drivers of fungal community composition in Corsica, at various scales and through three guilds: ectomycorrhizal, endophytic and saprotrophic fungi. We investigate the effect of disturbance (e.g. fire and treefall), environmental variables (e.g. soil depth), constraints due to the interacting plants (e.g. taxonomy) and dispersion on fungal communities. Some community assembly rules are similar across guilds. For instance, forests in different micro-regions of Corsica harbor dissimilar fungal communities. However relative importance of processes and the scales at which they occur vary across guilds. In Corsican pine forests, fifteen years after fire occurrence, soil fungal diversity is close to the level of diversity in unburnt stand. Despite the absence of effect on diversity, fire induces marked shifts in soil fungal community composition, in particular for soil saprobic fungi. We discuss the implication of this work for ecologists -- both plant and fungal ecologist -- and stakeholders.

More than half of the Pinaceae is including in genus Pinus covers the large parts of vegetation of northern hemisphere. The Anatolian Black Pine is one of the subspecies of European Black Pine, growing naturally as a widespread mid elevation species of Taurus, western Anatolian and northern Anatolian Mountains of Turkey. Although it is disputed that there are 5 varieties of Anatolian black pine but three of these are well recognized. These are Pinus nigra subsp. pallasiana var. pallasiana, Pinus nigra Arnold subsp. pallasiana var. pyramidata (pyrimidal black pine) and Pinus nigra Arnold subsp. pallasiana var. seneriana. To determine the genetic relationship between Anatolian black pine and its well recognized varieties, 3 different taxa of Anatolian black pine (well recognized varieties) were sampled in the natural range of species and non-coding trn regions of chloroplast DNA (cpDNA) were sequenced to assess the genetic structure of the species. Three sectors of trn region were examined. Analysis was assessed with using MEGA version 4.0 and Arlequin 2.000 softwares. Considering genetic diversity of three Anatolian black pine taxa with respect to trn regions and parsimonic sites, the result showed that P. nigra subsp pallasiana var seneriana was more polymorphic than other two taxa. Also, the most distant taxon that show differences in trn sequences when compared to other taxa was P. nigra subp pallasiana var pyramidata. The constructed phylogenetic tree showed that individuals of P.nigra subsp pallasiana var pyramidata were grouped together. However, other two taxa showed a dispersed allocation in the tree. This result indicates that var pyramidata was the most distant taxon. According to present study, there is no clear speciation between varieties and var pallasiana. The differences between them may be a result of mutation which may have occured in the genes coding for growth and form of Anatolian black pine.

Pinus nigra subsp. pallasiana is one of the most widespread and economically important forest tree species in Turkey. Primary objective of the present study was to to reveal the effects of forestry practices by determining genetic diversity of natural and managed seed sources by means of RAPD markers. Secondly, two varieties were also investigated to reveal their pattern of genetic variation. Seed stands, seed orchards and plantations were screened against 11 RAPD primers and generated 152 polymorphic DNA loci. Two varieties were compared with a reference seed source and 4 natural seed sources. Seven primers generated 66 polymorphic DNA loci. An overall average for effective number of alleles was 1.68&plusmn / 0.030 / observed heterozygosity was 0.49&plusmn / 0.024 / expected heterozygosity was 0.38&plusmn / 0.014 and proportion of polymorphic loci was 93% for all seed sources considered. Results revealed that there was no considerable variation between seed source categories but some degree of variation was observed within seed orchards and plantations. Mean FST value estimated for the natural populations revealed that 94% of the total genetic variation was within populations. Nei&rsquo / s genetic distance values were also estimated for seed source categories (0.03-0.14). Nevertheless, varieties&rsquo / genetic distance values were considerably higher than other natural seed sources (0.07-0.19). Their dendrogram also claimed that two varieties are genetically different from natural populations. The extent of genetic diversity explored by RAPD markers revealed that forestry practices caused no major changes in the managed populations with respect to natural populations. Moreover, further study is needed to illustrate genetic divergence of varieties.

No description available.

L'architecture des plantes est le résultat combiné des développements des structures topologique et géométrique qui interviennent dans l'acquisition de la biomasse et sa répartition sous l'influence des processus physiologiques. Pourtant cet aspect a été longtemps négligé dans la communauté des modèles dynamiques. Récemment les modèles structures fonction se sont montrés pertinents pour prendre en compte des questions comme les interactions plantes environnement (l'interception de la lumière), les interactions entre croissance et développement (répartition de la biomasse) en se plaçant au niveau de l'organe. Cependant les couts en calcul de la simulation numérique de ces processus rendent les applications impraticables en agriculture. Cette thèse vise a combiner le modèle structure fonction Greenlab avec d'une part un modèle de culture et d'autre part un modèle forestier basés sur le peuplement afin d'y introduire le concept d'architecture des plantes. Le modèle de culture Pilote fournit des prédictions de récoltes basés sur les paramètres de l'environnement (radiation, précipitations) et l'indice foliaire et l'indice de récolte. Une étude sur Maïs conjointe entre Pilote et GreenLab a permis d'expliciter en détail les paramètres de la production. Les indices foliaires et de récolte dépendent directement des paramètres sources puits, et la variabilité individuelle entre plantes est explicitée directement par les variations des retards a la germination et celles des surfaces disponibles par plantes (compétition spatiale). Tous ces paramétrés peuvent être calibré par méthodes inverses. Ainsi la jonction des deux types de modèles est réalisée au niveau du passage de la plante au peuplement.Une autre étude conjointe a été effectuée avec le modèle forestier empirique PNN qui modélise la croissance des peuplements forestiers de Pins noirs. A partir des données statistiques classiques sur les mesures de troncs et de houppiers, combinées avec les connaissances architecturales du Pin issues d'AMAP, GreenLab peut restituer l'architecture de l'arbre et visualiser des scenarios de sylviculture incorporant des élagages. Le procédé va jusqu'à l'obtention d'images de synthèse réalistes des peuplements. En conséquence il semble efficace de coupler les modèles de cultures et les modèles forestiers qui intègrent les connaissances écophysiologiques au niveau peuplement avec les modèles structures fonctions qui intègrent ces connaissances au niveau de l'architecture de la plante. Le modèle GreenLab par ses affinités avec ces deux types de modèles et ses performances en calcul, permet d'apporter un complément d'information essentiel sur la description du fonctionnement d'un peuplement tant du point de vue développement, que du point de vue des relations sources puits dans la plante. Enfin le modèle couplé a une plateforme comme Xplo (AMAP) permet en plus une simulation réaliste 3D du peuplement végétal aux divers stades de la croissance. / Plant architecture implies the development of both topological and geometrical structure over time, which determines resource acquisition, in the meantime interacts with physiological processes. However it has long been overlooked in traditional community dynamics models. Based on plant architecture, functional-structural plant models (FSPM) have showed their particular capability in addressing questions like interactions between plant and environment (e.g. light interception), between structure development and growth (e.g. carbon allocation), as they take into account morphogenesis with organ-level explicit descriptions. Anyway, high demand of time and memory for simulation and inverse calculation prevents FSPM from further agricultural or sylvicultural practice. This thesis attempts the combination of a mathematic FSPM GreenLab and a crop model or an empirical forest model (EFM) to introduce individual-based architectural support for community growth study. In the case of maize, disagreement from stand level (by crop model PILOTE) and individual level (by GreenLab) growth simulations implies different emergence time of individuals, which is used to quantify the distribution. By supposing that theoretical projective area (Sp) is determined by the growth situation and the final size of individual architecture, the variance of Sp is reversely computed with the variance of organ compartment measurements to characterize individual variability. In the case of Black pine, architecture dynamics built in GreenLab according to Rauh's model (architecture model for pine tree) are adapted to the simulation of an EFM PNN. As a consequence, thinning scenarios are well incorporated in the final stand visualization. From these preliminary applications, following conclusions can be drawn: (i) FSPM is able to provide individual performances (i.e. organ development and expansion) inside an area of crop field for crop models. (ii) The crop model may regulate the combined form of individuals from integral level. Both aspects are significant to deepen understanding of stand growth. (iii) Architecture conceptions integrated in FSPM may be adapted to EFM simulations for a data-driven visualization. (iv) EFM can guarantee ecological/sylvicultural function for 3D stand visualization. To take into consideration biomass processes, additional observations are needed. As models are independent in combinations, the same methods can be extended to linkage with other stand models.

La capitalisation sur pied et la substitution d'essences sont deux stratégies sylvicoles analysées dans cette thèse, chacune pressentie pour être favorable au stockage du carbone, enjeu majeur de ce XXIème siècle pour la lutte contre le réchauffement climatique. La première correspond à un ralentissement des récoltes, qui devrait générer un puits de carbone additionnel par l'augmentation des stocks moyens de biomasse sur pied. La substitution d'essences à croissance lente comme le Chêne sessile ou le Hêtre par des essences résineuses à croissance rapide comme le Pin laricio ou le Douglas pourrait entraîner une absorption plus rapide du CO2. L'impact sur le carbone de ces deux stratégies est d'autant plus intéressant à étudier que les gestionnaires forestiers les pratiquent déjà. La construction d'une chaîne de modèles prenant en compte l'ensemble des compartiments dans lesquels le carbone est impliqué, à savoir la biomasse forestière, le sol, mais aussi les produits forestiers issus de l'exploitation, permet d'effectuer des simulations donnant des résultats quantitatifs sur ces pratiques. Nous montrons qu'une capitalisation sur pied engendrerait un puits de carbone additionnel dépendant de l'état initial des peuplements, de la fertilité et de la nouvelle sylviculture pratiquée. Il pourrait s'élever jusqu'à 142 tC/ha après obtention du régime permanent dans le cas le plus favorable. La substitution de feuillus à croissance lente par des résineux à croissance rapide serait également un puits de carbone important (jusqu'à 2 tC/ha/an) pendant plusieurs décennies, mais s'avérerait d'un stock de carbone moyen inférieur sur le long terme.

Cloning of trees using somatic embryogenesis could have a major impact on tree breeding and commercial plantation forestry. To initiate somatic embryogenesis in Anatolian black pine (Pinus nigra Arnold. subspecies pallasiana), one-year old cones containing immature seeds were collected from eight trees located in METU campus, Ankara. Embryogenic tissues were derived from immature zygotic embryos excised from the seeds. The zygotic embryos at the time of collection were at the precotyledonary stage of development. For this study, Douglas-fir cotyledon revised medium (DCR) supplemented with 13.6&micro / M 2,4-D, 2.2&micro / M BAP, 0.5 g/L casein hydrolysate, 0.25 g/L L-glutamine and 3% sucrose was used. The media was solidified with 0.2% gelrite. Embryogenic tissue initiation was calculated for each genotype and collection date. Overall initiation frequencies were recorded as 0.92% for 2004 and 1.96% for 2005. Highest initiation frequency was calculated for 5-July 2005 sampling time (4.06). ANOVA revealed significant differences between trees and collection date for initiation frequencies. Also, ECL (Established cell lines) recorded after five subcultures. Overall, 0.38% and 0.62% of the initial explants were converted into ECLs for 2004 and 2005 respectively.