A part le défrichement pour l'agriculture, le comblement du déficit sur le marché local malgache en bois d'énergie et en bois d'œuvre fait partie des sources de la diminution de la couverture forestière à Madagascar. Afin de préserver les forêts naturelles malgaches, reconnues comme sources de méga-biodiversité, tout en remplissant les besoins en bois du marché local ; les forêts de plantation présentent un enjeu crucial pour Madagascar. Cependant, les bois provenant de la plantation forestière malgache, généralement dominée par les espèces du genre Eucalyptus et Pinus, offrent moins de choix et n'ont pas les qualités requises pour se substituer aux bois des forêts naturelles notamment pour l'ameublement et la menuiserie. Le bois de Liquidambar styraciflua est utilisé dans de nombreux pays en ameublement, emballage ou pour la fabrication de contreplaqués. Ce travail de thèse a pour objectif de contribuer à l'amélioration du Liquidambar styraciflua pour une sylviculture et une utilisation de son bois adaptées au contexte malgache. L'approche ici est originale car elle combine l'étude des caractères de croissance au champ, la production et la qualité grainière, la croissance juvénile et les propriétés des bois tout en considérant la variabilité génétique de l'espèce. Pour ce faire, les données d'inventaire annuels de l'essai de provenances de Liquidambar à Mandraka ont permis d'évaluer l'adaptation de l'espèce et la variabilité intraspécifique de sa croissance. Des échantillonnages de graines accompagnés de tests de germination et de croissance en pépinière ont été effectués pour évaluer la faculté de multiplication et sa variabilité afin de pouvoir se prononcer à la possibilité de vulgarisation de l'espèce. Enfin, ce travail porte également sur la caractérisation des propriétés physico-mécaniques et de durabilité naturelle du bois de Liquidambar. A l'issue de ces essais et de ces expérimentations, ce travail de thèse à mis en évidence que le Liquidambar de Mandraka montre une bonne adaptation avec une croissance élevée par rapport aux essais internationaux de provenances de Liquidambar promus par le Commonwealth Forestry Institute. De plus, la croissance de Liquidambar à Mandraka est semblable à celle des espèces du genre Eucalyptus mais meilleure par rapport à celle des Pinus quand ils sont plantés dans les mêmes conditions écologiques. La production grainière du Liquidambar de la Mandraka est plus élevée que dans son aire naturelle de distribution. Les graines de Liquidambar de la Mandraka présentent une vitesse et un taux germination élevé respectivement de 75% et de 83%. Ceci confirme la bonne adaptation de l'espèce dans les conditions d'étude. Nos travaux suggèrent que les arbres de grande dimension produisent des graines plus fertiles et les semis ont une croissance juvénile plus rapide (jusqu'à l'âge de 425 jours) par rapports aux semis issus des arbre-mères de taille plus petite. Ce travail de thèse a mis également en lumière que les méthodes indirectes de caractérisations du bois comme la Spectrométrie Proche Infra-Rouge, les ultrasons se sont avérées efficaces pour estimer les propriétés physico-mécaniques du bois de Liquidambar en plus des mesures standardisées également utilisées. Les propriétés physico-mécaniques du bois de Liquidambar sont moyennes parmi celles des bois communément utilisés. Les extractibles du bois de Liquidambar sont à l'état de traces et son bois n'est pas durable face aux attaques des termites du genre Reticulitermes et aux champignons Coniophora puteanea et Coriolus versicolor. Des corrélations phénotypiques faibles à fortes ont été observées entre les propriétés physico-mécaniques du bois de Liquidambar ; ce qui suggère qu'une amélioration sylvicole ou génétique visant à augmenter la valeur d'une propriété (physique ou mécanique) donnée pourrait avoir pour conséquence d'augmenter ou de diminuer la valeur d'autres propriétés physico-mécaniques. / Beyond the clearance for agricultural, the filling of the deficiency of wood as energy and material for the Malagasy local market takes part in the reduction of the forest cover in Madagascar. In order to preserve Malagasy natural forests, known to be a mega-biodiversity reservoir, with also full-filling the local demand in wood, the plantation forests represent a crucial challenge. Nevertheless, the timbers coming from the planted Malagasy forest, generally dominated by Eucalyptus and Pine species, offer less choice and do not have the required qualities to substitute the timber from natural forest, especially for carpentry, joinery and furniture manufacturing. Liquidambar styraciflua timber is used in many countries for packaging, veneer, plywood and furniture production. The objective of this work is to contribute to the improvement of Liquidambar styraciflua for a forestry and end-use in adequation with the Malagasy context. The approach used is original because it combines the study of the growing characteristics in the field, the production and the quality of the seeds, the juvenile growth and the wood properties, with considering also the genetic variability of the species. In order to do so, the inventory annual data of the provenance trial of Liquidambar in Mandraka has allowed evaluating the adaptation of this species and the intra-specific variability of its growth. Seed samplings, germination tests and tree nursery growth tests have been performed to evaluate the multiplication ability and its variability in order to state about the vulgarization possibility for this species. Finally, this work was also about the characterization of physic-mechanical and natural durability properties of Liquidambar timber. Once these trials and experiments completed, this work showed that Liquidambar from Mandraka presents a good adaptability associated with an important growth compared to other Liquidambar international provenance trials done by the Commonwealth Forestry Institute. Moreover, the growth of Liquidambar from Mandraka is similar to Eucalyptus species and better than Pinus species when planted in the same ecological environment. The seed production of Liquidambar from Mandraka is higher than in its natural distribution area. Its seeds present a high speed and rate of germination of 75% and 83%, respectively. This confirms the good adaptation of this species for the considered studied conditions. Our study suggest that tallest trees produce more fertile seeds and seedlings have a more rapid juvenile growth (up to 425 days) compared to seedlings coming from smaller mother tree. This work has also brought into light that indirect methods such as Near Infra-Red Spectroscopy, ultrasonic methods were efficient to estimate the physic-mechanical properties of Liquidambar timber, in addition to the standardized methods used. The physico-mechanical properties of Liquidambar timber are average compared to the most commonly used. Liquidambar timber extractible content is very low and it is not durable neither towards Reticulitermes termites, nor Coniophora puteanea and Coriolus versicolor Basidiomycete fungi. Low to strong phenotypic correlations between the physic-properties have been observed ; suggesting that a genetic or silvicultural improvement aiming to up-grade a property (physic or mechanic) could, in consequence, increase or decrease the value of another physic-mechanical property. Nevertheless, it would be interesting to get adequate experiments (test descendance from cross experiments) to estimate the genetic correlations. Concerning the variability, the physico-mechanical properties of Liquidambar timber follow a linear or logarithmic tendency from pith to bark, and normal, as well as tension wood was observed. The growing and multiplication characteristics of liquidambar are more variable than its physico-mechanical properties.

ABSTRACT GENETIC DIFFERENTIATION OF LIQUIDAMBAR ORIENTALIS MILL. VARIETIES WITH RESPECT TO matK REGION OF CHLOROPLAST GENOME &Ouml / ZD&amp / #272 / LEK, Asli M.S., Department of Biology Supervisor: Prof. Dr. Zeki Kaya August 2007, 87 pages Liquidambar L. genus is represented with mainly 4 species in the world and one of these species, Turkish sweet gum (Liquidambar orientalis Mill.) which is a relictendemic species is naturally found in only southwestern Turkey, mainly in Mugla Province. The limited distribution of species with two disputed varieties (var. integriloba Fiori and var. orientalis) and increased anthropogenic threats to its genetic resources signify the importance of studying genetic diversity in the species to have better conservation and management programs. For this purpose, 18 different populations were sampled throughout the species range and matK region of chloroplast DNA (cpDNA) was sequenced to assess the genetic structure of the species. Turkish Liquidambar orientalis populations were evaluated at two categories: variety level and geographic level. Also, two sectors of matK region were examined to assess which part of the region was more variable. All molecular analysis was conducted in this study by using MEGA version 3.1 and Arlequin 2.000 softwares. v Moleculer diversity analysis indicated that the population located in Fethiye- G&uuml / nl&uuml / kbasi district has the highest number of polymorphic sites. This population is also genetically the most distant from the others (average genetic distance 0.0038). Among the studied varieties, the average genetic distance within var. integriloba (0.0016) which also includes population Fethiye-G&uuml / nl&uuml / kbasi was the greatest. Among the geographic regions, Mugla-1 including Fethiye-K&ouml / ycegiz-Aydin district as well as population Fethiye-G&uuml / nl&uuml / kbasi showed the highest average genetic distances within the region with a value of 0.0015. According to the molecular variance results, among varieties and among geographic regions, there was no significant differentiation, but great amount of total variation was found (~86%) within Turkish sweet gum populations. With respect to the Fst values among varieties, the highest genetic differentiation was observed between var. orientalis and unknown group (0.040). Furthermore, based on the results of phylogenetic analysis, Turkish populations of L. orientalis have genetically closer to USA relative (L. styraciflua L.) than Chinese relatives (L. acalycina H.T Chang and L. formosana Hance). In conclusion, 10 Turkish sweet gum populations were found to be important for conservation issues. Furthermore, eight of these located in Mugla province and sixth of them belong to var. integriloba. Especially Fethiye-G&uuml / nl&uuml / kbasi, Marmaris&Ccedil / etibeli and Mugla-Kiyra populations should be included in either insitu or exsitu or in both conservation programs in the future.

Liquidambar L. genus are represented with four species in the world and one of these species, Turkish sweet gum (Liquidambar orientalis Miller) is naturally found only in southwestern Turkey with limited distribution in Mugla Province. The presence of increasing threats to its genetic resources signifies the importance of studying the phylogenetic relationships and genetic diversity in this relict endemic species. In this study, 18 different populations were sampled throughout the species range and noncoding transfer ribonucleic acid (trn) region of chloroplast DNA was studied to asses the phylogenetic relationships and genetic diversity. Experimental studies included the extraction of DNA, amplification and sequencing of the trn region of the chloroplast DNA. Molecular evolutionary analysis was done by using MEGA version 3.1 and Arlequin 2.000 softwares. Sequences from six other species of Liquidambar (L. styraciflua from USA, L. macrophylla from Mexico, L. formosana from Vietnam, L. acalycina from China, L. formosana from China and L. acalycina from USA) in the database were also included in the analysis. Moleculer diversity results show that population located in Mugla-Yatagan district has the highest number of polymorphic sites among the other populations of Turkish sweet gum. Population located in Marmaris-G&uuml / nn&uuml / cek has an average genetic distance value of 0.0032 within population, being the highest within the studied populations of Turkish sweet gum. The average genetic distance within variety orientalis (0.0011) was the greatest among all the varieties, but the most separated or divergent populations were members of variety integriloba. For both varieties and geographic groups, average diversity within was found to be the greatest portion (greater than 80%) of the total sequence diversity. The geographic groups located in Denizli and Mugla-Yatagan showed the highest average genetic distances within location, with a value of 0.0014. The genetic distance between the closest neighbor of Turkish sweet gum, American L. styraciflua was 0.0002, whereas the genetic distance between the most distant neighbors (Vietnamese L. formosana, Chinese L. acalycina and L. formosana) was 0.0051. Based on the molecular diversity analysis, seven populations were found to be important for conservation issues and two of them located in Marmaris have the highest priority. The most variant geographic groups are located in Denizli and Mugla-Yatagan districts. These populations could be considered as good candidates for future in-situ or ex-situ conservation programs

Thesis (Ph. D.)--University of Florida, 2006. / Includes bibliographical references (p. 97-106). Also available via the World Wide Web: http://etd.fcla.edu/UF/UFE0017365/morris_a.pdf.