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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Tree-age distributions in a northern hardwood forest

Cook, Bryan January 1971 (has links)
No description available.
42

Paprastojo buko (Fagus sylvatica L.) paplitimas, medynų sudėtis ir struktūra Norkaičių girininkijoje / Simplex fagus (Fagus sylvatica L.) spreading, trees composition and structure in Norkaiciai district

Lukošius, Tomas 21 June 2013 (has links)
Magistro darbe tiriama paprastojo buko (Fagus sylvatica L.) paplitimas, medynų sudėtis ir struktūra Norkaičių girininkijoje Darbo objektas – paprastojo buko medynai Norkaičių girininkijoje. Darbo metodai: Medynai su buku Norkaičių girininkijoje buvo parinkti dviejuose kvartaluose – 66 (sklypai 3; 4) ir 67 (sklypai 1;2), nes labiausiai juose buvo paplitęs paprastasis bukas. Parinkti tokie medynai: grynas bukynas (1 barelis Bu1-1); pušynas su paprastuoju buku (4 bareliai Bu3-1, Bu3-2; Bu4-1, Bu4-2); ąžuolynas su paprastuoju buku (2 bareliai - Bu2-1; Bu2-2). Buvo įrengti skrituliniai tyrimo bareliai, kuriuose nustatyta medyno struktūra, atskirų ardų dendrometrinė charakteristika, trako ir pomiškio rūšinė sudėtis ir gausumas, žolinės ir samanų dangos sudėtis ir gausumas. Darbo rezultatai. Didžiausias paprastojo buko medynų plotas buvo 1991 metais – 38.4 ha, dėl polajinių ir savaiminių želdinių įveisimo. Gryname bukyne vidutinis medyno amžius – 75 metai, skersmuo 1,3m. aukštyje – 25,1 cm, aukštis 25,8 cm, skerspločių suma – 25,1m2 / ha, tūris – 295 m3/ha. Gryname bukyne rasta paprastojo buko (10800 vnt/ha) ir paprastojo klevo (400 vnt/ha) savaiminukų. Pušynų su buko antruoju ardu vidutinis amžius buvo 70 metų, skersmuo 1,3 m aukštyje – 28,2 cm, bukų ardo vidutinis aukštis – 28,1 m, lajos skerspločių suma – 23,2 m2/ha, tūris -291 m3/ha. Šiame barelyje daugiausiai rasta paprastojo klevo savaiminukų ( 46000 vnt/ha mažiausiai – paprastojo buko... [toliau žr. visą tekstą] / Final work searching simplex beech (Fagus sylvatica L.) spreading, trees composition and structure in Norkaiciai district. The object of the study – simplex beech trees in Norkaičiai district. Method of the study: trees with beech Norkaičiai district was choose in two blocks - 66 (3;4 plots) and 67 (1;2 plots) because there was a lot of simplex beech. Choose these: pure beech (1 plot Bu1-1); pine trees with beech (4 plots Bu3-1, Bu3-2, Bu4-1 Bu4-2); oak with beech (two plots Bu2-1-; Bu2-2). Was arrange circle analysis plots, there was establish trees structure, diferences layer characteristic, glade and forest kind speading and adbundance of plants. Results of the study. Maxima simplex beech stat in area esset in 1991 - 38,4 ha hospitiis et spontanea lignum plantationis herba. Beech stet aperta mediocris aetatis - 75, diametrum - 25,1 cm 25,8 cm altum, basalibus area - 25,1 m2/ ha, Volume - 295 m3/ha. Pure beech (10800 vnt/ha) and maple (200 vnt/ha) trees. Pinus with second beech layer 70 years, diametrum – 28,2 cm, fagus quatit mediocris altitudo - 28,1 m, coronam basalibus area - 23,2 m2/ha, Volume -291 m3/ha. In these area was most maple trees (46000 vnt/ha), beech (200 vnt.ha). Oak with second beech layer 70 years old, altitudo diametrum - 16,7 cm, in mediocris altitudo fagus - 23,9 m corona basalibus area - 17,1 m2/ha, Volume 194 m3/ha.
43

Bokskog för framtiden : Planer och visioner för en bokplantering / Beech for future : Plans and visions for a beech plantation

Ingestad, Gunilla January 1900 (has links)
Objekt för undersökningen är en nyplantering av bok på en mindre skogsfastighet i sydöstra Blekinge. Bok och ek, som är de viktigaste ädla lövträden för den biologiska mångfalden, intog i dessa trakter en stor andel av skogsbeståndet fram till 1960-70-talet, men har sedan minskat i takt med att de ersatts av planterad gran. Det finns idag, bland annat i Skogsstyrelsens riktlinjer, en uttalad strävan mot en högre andel ädellövskog på de breddgrader som ingår i dessa trädslags naturliga utbredningsområden. På så sätt kan det projekt, som studien beskriver, anses ligga rätt i tiden. Inledningsvis ger rapporten en översikt över skog och skogsbruk som kunskapsområde och bakgrunden till att vi nu ser tendenser till att de traditionella formerna av skogsbruk, där ekonomi är den dominerande styrfaktorn, börjar ge vika för skogsbruksmetoder som gynnar även naturvårds- och sociala värden. Detta är en tendens som nu börjar få genomslag såväl i myndigheters styrdokument som i forskning och kunskapsutveckling. I rapporten beskrivs utvecklingen av en tio-årig plantering av bok, dels resultatet av den första fasen, etableringsfasen, och dels en bedömning av hur den framtida planeringen kan göras utifrån de uppställda målen med fokus på de skötselformer som kan betecknas som ”hyggesfria” eller ”naturnära” metoder. I analysen av studiens resultat görs jämförelser dels med liknande studier och dels med schabloniserade tillväxtprognoser för bok. En satsning på naturnära skogsbruk och på lövskog ger, enligt de sammanfattande slutsatserna, inte de högsta ekonomiska vinsterna i dagsläget. Däremot kan det, med ett långsiktigt skötselprogram, ses som en framtidsinvestering. Dels fås en kvalitetshöjning av framtida jordmån och växtbetingelser och större chans att klara stormar och dess effekter. En ytterligare vinst är möjligheten att vara med och bygga erfarenheter av och kunskap om utvecklingen av ett framtida lövskogsbruk. / The aim of this study was to evaluate an area, where planting of beech, Fagus sylvatica, has been made after clear cutting of spruce, Picea abies. Focus of the study was primary to follow-up the first phase of the planting, and also make an assessment of future planning based on such achievements as "selective cutting" or "natural" methods. In the result analysis comparisons are made with similar studies and also previous results for the area. An investment in natural methods for deciduous forest gives, according to the summary conclusions, not the highest economic gains in the current situation. However, with a long-term care program you can reach investment possibilities. On the one hand you get increase in quality of future soil and growing conditions, and greater chance of passing climate change and their effects. An additional profit is the opportunity to be part of building experience and knowledge of the development of a future broadleaved forest.
44

The status of Fagus grandifolia Ehrh. in the midwest : a comparative study of four virgin forests

Clevenger, Brenda K. January 1988 (has links)
This study was undertaken to investigate the status of the american beech as a possible waning species. Contrary to several authors, the results do not suggest a decline in the american beech population. The declines previously indicated probably result from the use of disturbed study sites and incomplete consideration of differences in mortality patterns. The data suggests a stable Beech-Maple forest with neither species experiencing permanent changes in populations. / Department of Biology
45

Discontinuous distributions of iconic New Zealand plant taxa and their implications for southern hemisphere biogeography : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Plant Biology at Massey University, Palmerston North, New Zealand

Knapp, Michael January 2007 (has links)
Content removed due to copyright restriction: Knapp M., Stockler K., Havell D., Delsuc F., Sebastiani F. & Lockhart P.J. (2005) Relaxed molecular clock provides evidence for long-distance dispersal of Nothofagus (southern beech). Plos biology 3(1), 38-43 / New Zealand has long been regarded as a key to understanding discontinuous distributions in the Southern Hemisphere. The archipelago is a fragment of the ancient super continent Gondwana. It has been isolated for 80 million years, has an excellent fossil record, and some of its most ancient biota such as the Southern Beeches (Nothofagus) and the Araucariaceae show disjunct distribution patterns with relatives on other fragments of Gondwana. Some of the most controversial problems of Southern Hemisphere biogeography with wide ranging implications involve New Zealand taxa. Three of them have been addressed in this thesis. The transoceanic relationships of the genus Nothofagus have long been regarded as an iconic example of a distribution pattern resulting from the break up of Gondwana. Phylogenetic analyses presented here show that, though most of the extant distribution of the genus is indeed shaped by tectonic events, Southern Beeches have crossed the Tasman Sea between Australia and New Zealand at least twice during the Tertiary period These results, together with findings of studies on other plant and animal taxa, emphasise the importance of dispersal but at the same time raise the question of whether any New Zealand taxa can be considered Gondwanan relicts. There is no geological evidence for the continuous existence of land throughout the Tertiary in the New Zealand area. However, molecular clock analyses presented in this thesis indicate that Agathis australis (New Zealand Kauri) diverged from its closest Australian relative prior to the Oligocene, or period of greatest submergence during the Tertiary. Thus these findings reject the hypothesis of the complete drowning of the New Zealand landmass during the Tertiary. They cannot reject the hypothesis of Stöckler et al. (2002) that the New Zealand Kauri lineage has persisted on the archipelago since its separation from Gondwana. Explanations for forest distribution patterns within the New Zealand islands themselves are diverse. New Zealand Nothofagus species show distribution gaps that are not explained by recent environmental factors alone. Early Miocene tectonic events and alternatively Pleistocene climates have been proposed as causes for this disjunct distribution pattern. Phylogeographic analyses reported in this thesis suggest that severe Pliocene and Pleistocene climates as well as Pliocene and Pleistocene tectonic events have shaped present day distribution and diversification of Nothofagus species in New Zealand.
46

Black bear (Ursus americanus) habitat ecology as related to aspects of forest management in southern New Brunswick /

Chamberland, Paul Eric Pierre. January 1900 (has links) (PDF)
Thesis (M.Sc.)--Acadia University, 2000. / Includes bibliographical references (leaves 123-128). Also available on the Internet via the World Wide Web.
47

Succession of an Upland Oak/Hickory Forest in the Central Hardwood Region

Hoover, Nathan 01 August 2018 (has links)
For the last 9,000-10,000 years the Central Hardwood Region (CHR) has been primarily composed of a mosaic of mesophytic communities in climax and communities of successional forest types dominated by oak (Quercus Linnaeus) and hickory (Carya Nuttall). Shade intolerant oak/hickory dominated forest types have been maintained by natural disturbance processes in synergy with anthropogenic causes, resulting in a large composition of communities which are neither at climatic nor edaphic climax. Reduction in fire events, thinning, forest grazing, and other disturbance processes over the last 80-100 years have coincided with decreased regeneration of shade intolerant species due to lack of adequate light availability and recruitment of shade tolerant species of communities dominated by American beech (Fagus grandifolia L.) and maple (Acer saccharum L.) into the overstory of forests typically dominated by oak/hickory. Forest inventory data at Trail of Tears State Forest was analyzed across two separate time events (1980 and 2014) to determine compositional and structural changes which have occurred. Density, basal area, and community patterns via ordination were compared across six Ecological Land Types (ELTs) to determine topography’s effect on composition. Community trends were analyzed via NMS Ordination and between ELTs by a Mantel Test. A Multi-Response Permutation Procedures (MRRP) was also used as a nonparametric method for assessing differences between ELTs examined in the NMS. Density and basal area between years for species, ELT, and species*ELT interactions were compared. Across all ELTs, between 1980 and 2014, overstory density decreased from 218 trees/ac in 1980 to 180 trees/ac in 2014 and basal area increased from 98 ft2/ac in 1980 to 106 ft2/ac in 2014. Maple basal area increased from 5 ft2/ac to 12 ft2/ac while beech increased from 1 ft2/ac to 8ft2/ac, signifying progression of these species from the understory up into the canopy. The component of soft masting species within the forest has also decreased sharply in the last 34 years. MRPP analysis of overstory compositional gradients reported distinct species compositions between ELTs, however the trend was weak (MRPP: p < 0.001, A = 0.038). NMDS ordination graphs confirmed MRPP showing little separation among ELTs. The final stress was 18.71146 and instability was < 0.01 after 212 iterations (Table 6). Our research at TTSF is a clear example of oak/hickory succession to beech maple on an upland site among species community types as delineated by topographic moisture gradient (ELTs) within the CHR. Expansion of beech and maple onto xeric ELTs suggests a breakdown of edaphic barriers that have previously been thought to be resistant to encroachment from mesophytic species. Currently oak decline induced by lack of management is likely the number one forest health issue resulting in loss of oak/hickory and other soft masting species.
48

Fosfito de potássio no controle de Phytophthora spp. em citros e faia e seu modo de ação / Potassium phosphite in the control of Phytophthora spp. in citrus and beech plants and its mode of action

Dalilla Carvalho Rezende 29 January 2015 (has links)
A citricultura brasileira ocupa lugar de destaque no agronegócio nacional, sendo o país o maior produtor de laranja e suco de laranja do mundo. A faia (Fagus sylvatica) é uma das principais espécies das florestas na Europa, sendo usada como ornamental e por possui alto valor econômico devido à produção de madeira. Um dos principais entraves no cultivo dessas espécies é a ocorrência de doenças principalmente as causadas por espécies de Phytophthora que além de causar grandes prejuízos, os métodos de controle são difíceis e onerosos. Existem trabalhos na literatura que apontam os fosfitos como alternativa sustentável, eficaz e economicamente viável para o controle de doenças causadas por oomicetos. Entretanto, o Comitê de Ação a Resistência à Fungicidas (FRAC) classifica os fosfitos, como produtos com ingrediente ativo sem mecanismo de ação definido. Neste contexto, este trabalho teve como objetivo avaliar o produto comercial à base de fosfito de potássio, Phytogard&reg; no controle das doenças causadas por Phytophthora nicotianae em citros e Phytophthora plurivora em faia, bem como avaliar através de análises bioquímicas se esse produto induz resistência em plântulas de citros. Além disso, foram realizados estudos in vitro para avaliar o efeito direto do Phytogard&reg; sobre o desenvolvimento de P. nicotianae e P. plurivora e verificar os possíveis mecanismos de ação desse produto sobre esses patógenos. Foram utilizadas plântulas de citros e faia que foram aspergidas com diferentes concentrações de Phytogard&reg; e, posteriormente, inoculadas com os patógenos. Foram avaliadas a incidência das doenças, o consumo de água e a quantidade de DNA dos patógenos nos tecidos das raízes dos hospedeiros. Ao final do experimento, foram realizadas análises bioquímicas dos tecidos das plântulas de citros. Nos experimentos in vitro, o micélio dos patógenos foi exposto a concentrações crescentes de Phytogard&reg; sendo determinado o crescimento micelial, produção de massa fresca de micélio e de zoósporos. Avaliou-se a perda de eletrólitos, peroxidação de lipídios e a atividade da enzima &beta;-1,3 glucanase do micélio exposto ao produto. Foi avaliada também a morfologia das hifas tratadas ou não com o Phytogard&reg; através da técnica de Microscopia Eletrônica de Varredura (MEV). Os resultados mostraram que o Phytogard&reg;, em todas as concentrações aplicadas controla de maneira preventiva as doenças causadas por P. nicotianae e P. plurivora em citros e faia, respectivamente. Em citros, o produto altera a atividade de algumas proteínas relacionadas à patogênese, mas não é possível concluir que o controle seja mediado por indução de resistência. O Phytogard&reg; inibe o crescimento micelial e a produção de zoósporos de P. nicotianae e P. plurivora. Além disso, o produto modifica a morfologia das hifas, atua na permeabilidade de membrana e na síntese de parede celular do micélio dos patógenos. / The Brazilian citrus production is important to national agribusiness, and the country is the largest orange and orange juice world producer. Beech (Fagus sylvatica) is one of the main forest species in Europe and is used as ornamental and also it has a high economic value due to the production of wood. One of the main problems in the cultivation of these species is the occurrence of diseases, mainly caused by Phytophthora species. Besides causing extensive damage control methods are difficult and costly. There are studies in the literature that show phosphites as a sustainable alternative, effective and economically viable for the control of diseases caused by oomycetes. However, the Fungicide Resistance Action Committee (FRAC), classifies the phosphites as products with the active ingredient with no defined mode of action. In this context, this work aimed to evaluate the commercial product based on potassium phosphite Phytogard&reg; on the control of diseases caused by Phytophthora nicotianae in citrus plants and Phytophthora plurivora in beech plants and evaluate through biochemical assays whether this product induces resistance in citrus seedlings. In addition, in vitro studies were carried out to evaluate the direct effect of Phytogard&reg; on the development of P. nicotianae and P. plurivora and to understand the possible mode of action of the product on these pathogens. Citrus seedlings were sprayed with different concentrations of Phytogard&reg; and then inoculated with the pathogen. We evaluated the diseases incidence, water uptake and the amount of pathogens DNA in the host roots. At the end of the experiment, biochemical assays with citrus seedlings were made. In in vitro experiments, the pathogen mycelium was exposed to increasing concentrations of Phytogard&reg; and mycelial growth, production of fresh mycelium and zoospores by these pathogens were determined. We also evaluated the electrolyte leakage, lipid peroxidation and the &beta;-1,3 glucanase activity in the mycelium exposed to the product. It was also evaluated the hyphae morphology from mycelium treated or not with Phytogard&reg; by using scanning electron microscopy. The results showed that in all concentrations of Phytogard&reg; preventively controled diseases caused by P. nicotianae and P. plurivora in citrus and beech plants, respectively. In citrus, the product changed the activities of some pathogenesis-related proteins, but it is not possible to conclude that the control was mediated by resistance induction. The Phytogard&reg; inhibited mycelial growth and zoospore production by P. nicotianae and P. plurivora. Furthermore, the product modified the hyphae morphology, changed membrane permeability and mycelium cell wall synthesis in the pathogens.
49

Impact of naturalness-promoting beech forest management on the forest structure and the diversity of breeding birds

Begehold, Heike 12 December 2017 (has links) (PDF)
Currently, existing European beech forests (Fagus sylvatica L.) are scarce and fragmented across vast parts of their potentially natural distribution. About 25 % of the global range of beech forests is located in Germany. Thus, Germany has a particular responsibility to integrate biodiversity conservation aspects into beech forest use. In this thesis, the influence of naturalness-promoting management on forest structure and breeding birds was investigated – in comparison to management without a biodiversity focus (different management) and forests sites that have been unmanaged for different periods of time (recently: unmanaged for 14-32 years as of 2012, and long-term: unmanaged for 65 years or since at least 1900). With a total area of 714 ha, 22 study sites located in the northeastern part of Germany were studied. Forest structure was studied using forest development phases (FDPs), which divide the forest life cycle into different periods. FDPs are characterized by a defined combination of five structural parameters such as canopy cover, diameter at breast height, tree height, regeneration cover and deadwood amount. FDPs were mapped during the winters of 2012 and 2013 according to a dichotomic decision tree. Breeding bird abundances were determined in 19 study sites and each study site was mapped 10 times between March and July of the same years using a territory mapping method. FDP patterns such as proportions, patch sizes, distances between patches of the same FDP, evenness, FDP transition within a decade and transition diversity, as well as bird abundances and development of bird densities within a decade were analyzed. Study sites under naturalness-promoting management differ clearly from differently managed sites and they are comparable or develop similarly to (long-term) unmanaged stands regarding FDP patterns. This also applies for the composition of the breeding bird community and the development of breeding bird species within a decade. The effect of naturalness-promoting management within the last decade is strong as evidenced by: significant decreases in FDP patches in size, the development of FDP richness towards a complete set; the comparability of transition proportion and transition diversity with long-term unmanaged sites (for former gaps, regeneration phase, early-, mid- and late optimum phase as well as disintegration phase); the higher total abundances of all breeding birds as compared with differently managed and recently unmanaged sites; and the highest number of increasing bird species amongst all management types. Further, the occurrence of breeding birds is linked to FDPs. On the one hand, the breeding bird community has a strong preference for FDPs of later-stages such as the terminal and disintegration phases. On the other hand, every bird species has its own set of preferred and avoided FDPs and every FDP has several bird species preferring it. Thus, a complete set of all FDPs at small scale is necessary for the habitat requirements of birds inhabiting beech forests. In conclusion, 1) the positive impact of naturalness-promoting management on forest biodiversity is already detectable after a decade and 2) FDPs are a suitable indicator can be used as an innovative indicator for monitoring the impact of forest management on biodiversity.
50

Vers une voie de valorisation du hêtre : synthèse de monomères furaniques biosourcés et furfurylation / Towards a valorisation pathway of beech : synthesis of bio-based furan monomers and furfurylation

Imbert, Aurélia 19 December 2017 (has links)
Le hêtre est une essence très répandue sur le territoire français et plus particulièrement dans la région Grand-Est. Toutefois, son bois est peu exploité, notamment pour des utilisations en conditions extérieures en raison de sa faible durabilité et son instabilité dimensionnelle. Pour favoriser et développer son utilisation, il est nécessaire de le traiter afin de limiter sa reprise en humidité et de le protéger contre les champignons de pourriture. Par ailleurs, la réglementation actuelle sur les produits de traitement du bois impose la mise au point de solutions alternatives respectueuses de l’environnement et de la santé. Dans ce cadre, les travaux développés durant cette thèse visent la valorisation du hêtre en tant que matériau via sa protection par un traitement « non-biocide », la furfurylation. Cette méthode consiste à polymériser in situ de l’alcool furfurylique dans le bois de hêtre. La mise au point du procédé a permis d’aboutir à du hêtre composite dont la durabilité et la stabilité dimensionnelle sont nettement améliorées. D’autre part, le hêtre est une essence feuillue pour laquelle la fraction hémicellulosique est riche en pentoses et plus précisément en xylose, précurseur de furfural. Des travaux ont donc été menés pour produire du furfural par hydrodistillation acide à partir de connexes issus de l’industrie de la première transformation du hêtre. Le furfural a ensuite été réduit en alcool furfurylique par transfert d’hydrogène. Les résultats prometteurs obtenus montrent qu’il est possible de mettre en place une filière locale alliant le hêtre comme source de molécules furaniques et le bois de hêtre comme matériau / Beech is a wood species present in the French territory, particularly in the Grand-Est region. However, beech is a under used wood, especially for outdoor uses, because it is non durability and it is dimensional unstability. To promote and develop its use, it is necessary to limit its recovery in moisture and treat to protect it against fungi decay. Futhermore, current regulation on wood treatment products imposes the development of alternative wood treatments more respectful of the environment and health. In this context, the work developed during this thesis is focused on valorisation of beech as a material through its protection by a “non-biocide” treatment, furfurylation. This method consists in an polymerisation in situ by heating a furfuryl alcohol solution into beech solid wood. The development of process led to a bio-based beech composite with significantly improved durability and dimensional stability.On the other hand, beech is a hardwood species in which the hemicellulosic fraction is rich in pentoses, and more precisely in xylose, precursor of furfural. Work has been done to produce furfural by acidic steam distillation, from beech primary wood processing by products. This molecule is then chemically reduced to furfuryl alcohol by hydrogen transfer.These promising results to show that it is possible to set up a local production combining beech as a local source of furanic molecules and beech wood as a solid material

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