Dissertations / Theses on the topic 'Seedling bank'

Abstract The aims were to examine the importance of regeneration by seeds, the influence of plant traits and disturbances, and the role of seed-seedling conflicts in regeneration and in the determination of vegetation structure. The study was carried out at in a subarctic alpine area (Kilpisjärvi 69°01'N 20°50E', Finland). Seed bank and seedling densities were high in many plant communities (ranges 99 -1109 viable seeds/m2 and 0.2-227 seedlings/m2, respectively). Effective seedling recruitment is reflected in vegetation as a high proportion of plants with poor or no vegetative reproduction ability. This development may take place in meadows and snowbeds where herbs (e.g. Gnaphalium supinum, Sibbaldia procumbens, Veronica alpina and Viola biflora) are abundant. On the other hand, the low proportion of these plants in heath vegetation reflects ineffective seedling recruitment. Floristic similarities between the consecutive phases in the regeneration pathway may be low despite effective seedling recruitment. Clonality, large and small seed sizes and appendaged diaspores limit the movement of species from phase to phase. Generally, disturbances facilitate effective regeneration by seeds. Grazing promotes species with large seed banks and is therefore one reason for high seed bank densities. Freezing and melting processes negate a negative influence of altitude on seed bank densities in the phase of seedlings. However, if disturbances are severe and continuous and the soil is compact, unstable or dry, disturbances are not beneficial. The same is true if there is a shift in the species composition of seedlings from gaps to closed vegetation. This phenomenon occurred in a rich meadow. Seed-seedling conflicts limit regeneration by seeds in low-herb snowbeds and Ranunculus glacialis-Gymnomitrion snowbeds. Vegetative reproduction and infrequent pulses of seedling recruitment negate an influence of short-term seedling recruitment on the spatial structure of vegetation. Extreme conditions, such as low temperatures, instability of the soil and late snowmelt modify the influence of factors that are important in more moderate conditions. To conclude, all transitions limit regeneration by seeds. However, favourable conditions (e.g. moist conditions in a meadow) partly eliminate the obstacles against seedling emergence. Regeneration by seeds therefore has a major impact on the dynamics and structure of vegetation. In heath vegetation, where bare soils are dry and the moss cover is thick, large seed banks and seed rains do not guarantee effective seedling recruitment. The regeneration process is reduced in the early phases, and plants that reproduce primarily by seeds have a minor role in vegetation. The accumulation of seed banks is effective in these circumstances.

The seagrass Zostera japonica Aschers. and Graebn. occurs as pure populations and in mixture with Zostera marina L. along the intertidal regions of southwest British Columbia. At the Roberts Bank study area seed and seedling dynamics were studied in three vegetation zones: a landward monospecific zone of Z. japonica, a zone of co-existing Z. japonica and Z. marina, and a seaward monospecific zone of Z. marina. Many more seeds were produced than were found in the sediment, and even fewer germinated. Zostera japonica seeds were most abundant in the seed bank in the upper zones where there is high Z. japonica density. Even though seeds remained in the water column for up to two months, very few seeds dispersed into the lower zone populated by Z. marina. thus limiting Z. japonica's colonization of the lower zones. It is unclear what limits the dispersal of Z. japonica seeds. Of the seeds that were incorporated into the sediment few germinated (5% or less). When seeds were planted in buckets placed into the sediment, with and without Z. marina, Z. japonica was able to germinate, grow, and reproduce in one year throughout the study area. Seedlings that emerged earliest (in April) either did not establish or did not survive as long as those seedlings that emerged later in May and June. Seedlings were often found uprooted, floating in the water. The rim of the buckets and the presence of Z. marina shoots appeared to protect the Z. japonica seedlings, preventing uprooting, but the results were not conclusive. Once seedlings became established, they spread vegetatively at a rapid rate and can persist throughout the winter, either as reduced shoots or as overwintering rhizomes. These overwintering plants contribute greatly to the following year's population.<br>Science, Faculty of<br>Botany, Department of<br>Graduate

xviii, 160 p. : ill. (some col.)<br>Salt marshes are intertidal communities dominated by halophytic vascular plants that are subjected periodically to tidal inundation. These species have developed various adaptations to this stress, including tolerances of fluctuating salinity, extended periods of inundation and intervals of anoxic conditions. The marshes are divided into zones of different plant communities based on species' tolerances of ambient estuarine conditions. Abiotic stresses change along the estuarine salinity gradient (marine to riverine), potentially altering development and composition of plant communities. Abiotic gradients associated with tides are not the only factors that contribute to development of plant community composition in salt marshes. Both negative (competition) and positive (facilitation) biological interactions are also important. Factors that influence community structure in salt marshes, particularly on the eastern North American seaboard, have been well studied. In contrast, salt marshes along the Oregon coast are smaller and more discrete and have received comparatively little attention. The community structure and seed bank composition of six marshes along an estuarine salinity gradient were evaluated. Four major community types dominated marshes that varied in the salinity of inundating tidal waters. Community types were relatively consistent throughout the estuary despite the distances between the marshes. Unlike the emergent plant communities, marsh seed bank composition was more similar within a marsh than within a community type. The low and high marsh community types were separated by a distinct boundary in the marine marshes. Although abiotic factors influence the physical separation of communities, competitive interactions commonly determine the upper limit of a species. In Metcalf marsh, however, the upper boundary for two dominant low marsh species was not determined by competition with the high marsh dominant species. Positive biotic interactions between seedlings and existing vegetation in a community are important factors in determining species distributions, particularly in stressful estuarine environments. In salt marshes, where abiotic stress can be harsh, presence of existing vegetation can ameliorate these conditions and enhance germination and seedling establishment. However, interaction between seedlings and the emergent marsh community was highly competitive, though germination of one species was enhanced in the presence of existing vegetation. This dissertation includes un-published co-authored material.<br>Committee in charge: Dr. Scott Bridgham, Chairperson; Dr. Richard Emlet, Advisor; Dr. Steven Rumrill, Member; Dr. Alan Shanks, Member; Dr. Gregory Retallack Outside Member

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES<br>Many researches have been focused on reforestation projects, taking advantages on the self recuperation mechanism of the frorest such as seed rain, soil seed bank and seedling banks. Seed rain is an initial process which develops the dynamic, organization and structuration of the forest. However, the seed bank is one of the most important factors for natural recolonization of affected areas which start the succession process. Through this natural regeneration, a set of individuals are able to be recruited to the upper stages. In this way, the present study was performed aiming to evaluate the plant species establishment strategies through natural regeneration, in an area in the city of Laranjeiras-SE. Thirty plots were installed, and in center of these plots, collectors were installed (1m x 1m) to estimate the seed rain. To characterize the seed bank, was collected from August 2014 (corresponding to the rainy season in the region) to February 2015 (dry season), a soil sample from the center of each subplot (1m x 1m) through a metal jig which was introduced into the soil to remove a 5 cm layer. In the seedling bank evaluation, height and diameter of seedlings were analyzed between August 2014 (rainy season) and Februare 2015 (dry season) in subplots (1m x 1m). In seed rain were found 7,788 seeds, in which Shinus terebinthifollius Raddi (aroeira) presented a higher number of seeds collected with 6,799 samples and its frequency was 87.84% in relation with others species. The autochoric syndrome of dispersion was observed to Centrosema brasilianum (L.) Benth., Fabaceae 2 and Anadenanthera colubrina (Vell.) Brenan, for Asteraceae 1 and Bignoniaceae 1 the dispersion syndrome observed was anemocoric and to Schinus terebinthifollius and Passiflora mansoi (Mart.) Mast, the dispersion syndrome was zoochoric. In the study of seed bank, it was found a total of 171 seeds. The seed bank analyzes by the rainy season and dry season, Schinus terebinthifollius prevailed with more individuals in the rainy season. However, Fabaceae sp prevailed in the dry season. The distribution of species per plot was heterogeneous in both seasons, but presented a better distribution in the rainy season. In the study of seedlings bank, samples were found belonging to seven families and thirteen species. Shinus terebinthifollius represented 28% of total specimen, followed by Genipa Americana L. with 20%. The rainy season showed better seedling distribution along the plots. The processes of natural regeneration at studied area have presented a diversity of species into three regeneration kinds evaluated in different fructification seasons, establishing int this way, a steady supply of seeds, enabling the development of new individuals for future process.<br>Inúmeras pesquisas têm sido voltadas a projetos de reflorestamentos, aproveitando o próprio mecanismo de recuperação da floresta como chuvas de sementes, bancos de sementes do solo e bancos de plântulas. A chuva de sementes é um processo inicial que desenvolve a dinâmica, organização e estruturação da floresta. No entanto, o banco de sementes é um dos fatores mais importantes para a recolonização natural das áreas afetadas dando início ao processo sucessional. Por meio dessa regeneração natural, um conjunto de indivíduos são capazes de ser recrutados para os estádios superiores. Dessa forma, o presente trabalho foi realizado objetivando avaliar as estratégias de estabelecimentos das espécies vegetais por meio da regeneração natural, numa área em reflorestamento, no município de Laranjeiras-SE. Foram instaladas 30 parcelas, e no centro dessas parcelas foram instalados coletores (1m x 1m) para estimar a chuva de sementes. Para a caracterização do banco de sementes, foi coletada, no mês de agosto de 2014 (correspondente a estação chuvosa na região) e fevereiro de 2015 (estação seca), uma amostra de solo no centro de cada subparcela (1m x 1m), através de um gabarito metálico que foi introduzido no solo para remover uma camada de 5 cm. Na avaliação do banco de plântulas, foram realizadas análises de altura e diâmetro das plântulas, entre agosto de 2014 (estação chuvosa) a fevereiro de 2015 (estação seca), em subparcelas (1m x 1m). Na chuva de sementes foram encontradas 7.788 sementes, dentre as quais a espécie Schinus terebinthifollius Raddi (aroeira) apresentou maior número de sementes coletadas, com 6.799 amostras possuindo frequência de 87,84% em relação as outras espécies. A síndrome de dispersão autocórica foi observada para as espécies Centrosema brasilianum (L.) Benth., Fabaceae 2 e Anadenanthera colubrina (Vell.) Brenan, para Asteraceae 1 e Bignoniaceae 1 a síndrome de dispersão observada foi anemocorórica e para as espécies Schinus terebinthifollius e Passiflora mansoi (Mart.) Mast, a síndrome de dispersão presente foi a zoocórica. No estudo do banco de sementes, foi encontrado um total de 171 sementes. Nas análises por estação chuvosa e seca do banco de sementes, a espécie Schinus terebinthifollius prevaleceu com maior número de indivíduos na estação chuvosa. Contudo, prevaleceu a espécie Fabaceae 1 na estação seca. A distribuição das espécies por parcela foi heterogênea em ambas as estações, porém apresentou uma melhor distribuição no período chuvoso. No estudo do banco de plântulas, foram encontradas amostras pertencentes a sete famílias e treze espécies. A espécie Schinus terebinthifollius representou 28% dos espécimes amostrados, seguida por Genipa americana L. com 20%. Na estação chuvosa houve uma melhor distribuição de plântulas ao longo das parcelas. O processo de regeneração natural da área de estudo apresentou uma diversidade de espécies nas três formas de regeneração avaliadas com diferentes épocas de frutificação, estabelecendo assim, uma constante oferta de sementes, viabilizando o desenvolvimento de novos indivíduos para processos futuros.

O acúmulo significativo de conhecimento sobre a ecologia de restauração nos últimos anos tem conduzido a mudanças na orientação dos programas de manejo e restauração florestal. A escolha ou criação de um modelo de restauração é um processo em constante aprimoramento, exigindo a necessidade de estudos que não apenas diminuam os custos envolvidos, mas também, que garantam a efetividade do objetivo proposto. Neste sentido, este trabalho testa novas metodologias de restauração visando a obtenção de informações técnicas sobre: A) a expressão do banco de sementes autóctone e alóctone na restauração florestal de diferentes situações de degradação antrópica.; B) o resgate de plântulas e indivíduos de espécies arbustivo-arbóreas regenerantes; C) a eficiência de um modelo de plantio que utiliza conceitos de Preenchimento e Diversidade e; D) a evolução da paisagem. Para análise dos bancos de sementes autóctone e alóctone foram feitos levantamentos da densidade e das espécies arbustivo-arbóreas regeneradas. No resgate de indivíduos de espécies arbustivo-arbóreas regenerantes, as plântulas e indivíduos jovens foram resgatadas em uma floresta e levadas para adapatação em viveiro, onde tiveram seus indivíduos e espécies contabilizados em termos de densidade e sobrevivência. No modelo de plantio estudado, as espécies foram reunidas em grupos de Preenchimento e Diversidade e tiveram a cobertura de copa de cada indivíduo quantificada. A evolução da paisagem foi realizada através de fotointerpretação e principalmente checagem de campo periódica. Os principais resultados dessas metodologias foram: A) As situações identificadas na Fazenda Intermontes apresentaram diferentes expressões de regeneração natural em função do número de indivíduos germinados banco de sementes autóctone. O aproveitamento dessa expressão poderá ser realizado através de metodologias diferenciadas de restauração para cada situação estudada: B) No estudo do Banco de sementes alóctone, a densidade dos indivíduos germinados se foi de 409.334 indivíduos/ha, revelando a possibilidade de uso no programa de restauração. Os indivíduos arbóreos apresentaram na área adubada um acréscimo de 137,3 % em sua altura média em relação aos indivíduos da área não adubada. C) No resgate de plântulas e indivíduos de espécies arbustivo-arbóreas regenerantes, a densidade dos indivíduos foi muito próxima para as duas épocas do ano, sendo 38.700 ind./ha e 37.900 ind./ha, mas com uma diferença significante para os indivíduos sobreviventes que apresentaram 16.500 ind./ha e 26.600 ind./ha para os meses de julho e dezembro de 2002, respectivamente. A técnica de resgate utilizada se mostrou viável uma vez que foi possível alcançar até 70,9% de sobrevivência para os indivíduos resgatados; D) No estudo sobre o modelo de plantio foram amostrados 143 espécies, demonstrando que a função do grupo da diversidade vem sendo mantida e aumentando as chances de efetivação dos processos de sucessão. Os resultados mostraram que o grupo de Preenchimento apresentou-se com uma porcentagem de cobertura significativamente maior que a do grupo de Diversidade, sendo 73,6% e 83,3% para 1,5 e 2,5 anos respectivamente.<br>Significant accumulation of know-how about restoration ecology has been changing forest restoration management programs’ trends during the last years. Choosing or elaborating a restoration model is a process that requires constant improvement and ecological studies that not only reduces the costs involved but also warrants the achievement of the aimed proposal. This study explores new restoration methodologies, searching for technical information about: A) autochthonous and allochthonous seed bank expression on forest restoration at different situations degraded by anthropogenic disturbances; B) seedlings and woody growing individuals rescue; C) efficiency of a planting model based on fulfillment and diversity concept; D) landscape development. The autochthonous and allochthonous seed bank were analyzed through regenerating woody species and density scouting. For the rescue of regenerating woody species, seedling and young individuals were taken from a forest and transferred to a plant nursery for adjustment, where number and species were counted regarding density and survival. In this studied planting model, species were organized and gathered into a fulfillment or diversity group, and each individual had its crown area quantified. Landscape development was analyzed by photointerpretation and specially by periodical field checking. Results from these methodologies showed that: A) Identified degraded situations at Intermontes farm displayed distinguished natural regeneration expression, influenced by the number of germinated seeds of the autochthonous seed bank. Advantage can be taken from these different outcomes by using distinct restoration methodologies for each studied situation. B) For the autochthonous seed bank study, germinated seed density was 409,334 ind./ha, indicating its potential role on restoration programs. Woody individuals at fertilized sites had a medium height enhancement of 137,7% when compared to those at non fertilized sites. C) For seedlings and woody growing individuals rescue, individual density was similar for both seasons (38700ind./ha and 37900ind./ha) but significantly distinct for individual survivor, with values of 16500ind./ha for July and 2600ind./ha for December. Rescue technique turned out to be a viable possibility since it achieved survival of 70,9% for rescued individuals. D) This planting model study registered 143 species, indicating that the diversity group’s role has been maintained and enhances the chance of successional process success. The fulfilling group had a significant higher percentage of crown area than the diversity group, with 73,6% and 83,3% for 1,5 and 2,5 years, respectively.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior<br>Velloziaceae is a relatively small family from Pandanales, including approximately 250 species that are very common in the brazilians campos rupestres . The Velloziaceae have a high degree of endemism, and some species are threatened with extinction. Several species of Velloziaceae have potential ornamental use, both for plant architecture as the foliage, or due to the beauty of their flowers. However, few studies investigate the germinative behavior and the post-seminal development of these species. In order to contribute with the knowledge of the germination and post-seminal development of Velloziaceae were analyzed seeds of twelve species of Vellozia Vand. from Minas Gerais and Goiás campos rupestres . The seeds were sown in Emanueli chambers and the experiments were installed in germination chamber under controlled light and temperature. The data about germinative behavior and post-seminal development morphology and anatomy were obtained using the usual techniques for each case. The seeds of the studied species are small, preferentially photoblastic and most of them exhibit high germinability (G &#8805; 60%) and high values of mean germination rates (0,06 &#8804; v &#8804; 0,21 day-1). The coefficient of variation of the germination time and the measurements of uncertainty and synchrony revealed that the species can be separated in two groups: in the first group are the species exhibiting heterogeneous and spread germination through the time and in the second group were coupled the species exhibiting homogenous germination more concentrated over time. The photoblastism and fast germination, yet spread in time, suggest relative dormancy, which is common in seeds from species adapted to adverse environmental conditions and indicate that the seeds of these species can form seed banks. The seeds are small and bitegumented. The embryo is small and exhibits a single vascular bundle in the cotyledon. Germination begins with the protrusion of the cotyledon s base and radicle and the seedling is criptocotylar. The primary root is persistent and forms lateral roots. Eophyll and methaphyll are similar. Seedling vascularization is reduced. The Vellozia exhibited similar morphological and anatomical characters during the post-seminal development, which reinforces the genera identity.<br>As Velloziaceae, uma família relativamente pequena da ordem Pandanales, com aproximadamente 250 espécies, são frequentemente encontradas nos campos rupestres do Brasil, onde apresentam alto grau de endemismo, bem como, algumas espécies encontramse ameaçadas de extinção. Várias espécies de Velloziaceae apresentam potencial ornamental, tanto pela folhagem, quanto pela beleza das flores. No entanto, poucos são os estudos que investigam o comportamento germinativo e o desenvolvimento pós-seminal dessas espécies. Visando contribuir com esses estudos, sementes de doze espécies de Vellozia Vand. foram coletadas nos campos rupestres de Minas Gerais e Goiás. As sementes foram semeadas em Câmaras de Emanueli e os experimentos instalados em câmara de germinação, sob luz e temperatura controladas. Os dados sobre o comportamento germinativo e a morfoanatomia foram obtidos utilizando-se as técnicas usuais para cada caso. As sementes das espécies estudadas são preferencialmente fotoblásticas e a maioria delas apresentou alta germinabilidade (G &#8805; 60%) e velocidade média de germinação alta (0,06 &#8804; v &#8804; 0,21 dia-1). O coeficiente de variação do tempo de germinação, as medidas de incerteza e de sincronia revelaram que essas espécies podem ser agrupadas em dois grupos: no primeiro, aquelas que apresentam germinação heterogênea e espalhada no tempo e, no segundo, as que exibem germinação homogênea e mais concentrada no tempo. O fotoblastismo e a germinação rápida, porém espalhada no tempo, sugerem dormência relativa, que é comum para sementes de espécies adaptadas às condições ambientais adversas e indica o potencial dessas sementes para formar banco de sementes. As sementes de Vellozia são pequenas e bitegumentadas. O embrião é pequeno e exibe um único feixe vascular no cotilédone. A germinação inicia-se com a protrusão da base do cotilédone e da radícula e a plântula é criptocotiledonar. A vascularização da plântula é reduzida. A raiz primária é persistente e forma raízes laterais. Eofilo e metafilo são semelhantes. As Vellozia estudadas apresentaram caracteres morfoanatômicos semelhantes durante o desenvolvimento pós-seminal, o que reforça a identidade do gênero.<br>Mestre em Biologia Vegetal

Orientador: Veridiana de Lara Weiser Bramante<br>Resumo: O Cerrado é considerado um dos 25 hotspots mundiais, uma das áreas prioritárias para a conservação da biodiversidade mundial, por apresentar uma alta biodiversidade, um alto grau de endemismo e suas espécies estarem ameaçadas de extinção. Sendo assim, é fundamental o desenvolvimento de estudos na vegetação de cerrado para subsidiar trabalhos de conservação, manejo e restauração ecológica. O presente estudo visou conhecer as espécies que constituem o estrato de regeneração natural de uma área de cerradão na Gleba II do Refúgio de Vida Florestal Aimorés, em Bauru, centro-oeste do estado de São Paulo, sudeste do Brasil. Por meio do método de parcelas, realizamos o inventário da regeneração natural em duas classes de altura. A classe I (H ≤ 50 cm), chamamos de banco de plântulas e amostramos em subparcelas de 2 m x 2 m e a classe II (50 cm < H ≤ 1 m) chamamos de jovens regenerantes, amostramos em subparcelas de 5 m x 5 m. Alocamos as duas subparcelas no canto inferior esquerdo de 25 parcelas permanentes de 10 m x 10 m. Para cada classe de altura da regeneração natural analisamos os parâmetros de riqueza e abundância, calculamos o índice de diversidade de Shannon (H’) e equabilidade (J), os índices de regeneração natural por classe (RNC) e total (RNT).Utilizamos o índice de Sorensen para avaliar a similaridade florística entre as classes de altura da regeneração natural e entre a regeneração natural como um todo e o estrato arbóreo amostrado em dois períodos, 2005 e 2019. Amostram... (Resumo completo, clicar acesso eletrônico abaixo)<br>Abstract: The Cerrado is considered one of the 25 hotspots, one of the priority areas for the conservation of global biodiversity, as it presents a high biodiversity, a high degree of endemism and its species are threatened with extinction. Therefore, it is essential to develop studies in the cerrado vegetation to support conservation, management and ecological restoration work. The present study aimed to know the species that constitute the natural regeneration stratum of woodland cerrado area in the Wildlife Refuge Aimorés, in Bauru, middle west of the state of São Paulo, southeastern Brazil. Using the plot method, we carried out the inventory of natural regeneration in two height classes. Class I (H ≤ 50 cm), we call the seedling bank and sample in subplots of 2 m x 2 m and class II (50 cm <H ≤ 1 m), young regenerators, we sample in sub plots of 5 m x 5 m. We allocated the two subplots in the lower left corner of 25 permanent plots of 10 m x 10 m. For each height class of natural regeneration, we analyzed the parameters of species richness and abundance, calculating the Shannon diversity index (H') and equability (J), the natural regeneration indices by class (RNC) and total (RNT). We used the Sorensen index to assess the floristic similarity between the height classes of natural regeneration and between natural regeneration and the tree strata sampled in two periods, 2005 and 2019. We sampled 617 individuals from the seedling bank, belonging to 44 species and 680 young regenerating... (Complete abstract click electronic access below)<br>Mestre

Conselho Nacional de Desenvolvimento Científico e Tecnológico<br>The ecology of regeneration and population dynamics is necessary information to the conservation and management of forest ecosystems. Thus, this study aimed to characterize: a) the mechanisms of natural regeneration in a Mixed Rain Forest remnant and b) the population structure of Araucaria angustifolia (Bertol.) Kuntze, Blepharocalyx salicifolius (Kunth) O. Berg and Ilex paraguariensis A. St.-Hil. Therefore, the structure of the sample project PELD/CNPq was utilized, which was installed in the National Forest of São Francisco de Paula, RS, Brazil to evaluate six clusters (1 ha), with 16 plots (20 x 20m) each, disregarding 10m surround. The mechanisms of regeneration that have been evaluated were seed rain (SR), soil seed bank (SB) and a seedling bank (SeB) (individuals ≥ 30cm in height and diameter at breast height (DBH) <1cm). Additionally, natural regeneration establishment (RNE) (1 ≤ DBH <4.8 cm) sampled in cells of 3.16 x 3.16m, the size class I (SC I) ( 4.8 ≤ DBH <9.55 cm) in plots 10 x 10m and SC II (DBH ≥ 9.55 cm) shown on 96 plots of 20 x 20m were also considered for the study of populations. These data were collected in 2008, also being measured the DBH and sociological position. The mechanisms of regeneration were evaluated for the floristic composition and horizontal structure. In addition, the cluster analysis method TWINSPAN (Two-way Indicator Species Analysis) and canonical correspondence analysis (CCA) were performed for the SeB. The population structure of the three species was examined by characterization of the sociological position, spatial distribution and frequency in size classes. In SR, we sampled 81 species, 46 genera and 28 families, in SB, 103, 65 and 41 and in SeB, 88, 57 and 36, respectively. The analysis by TWINSPAN ordered the formation of three groups in SeB, with their history of interference and environmental conditions. The CCA indicated the slope as environmental variable with the greatest influence on the distribution of plots and species. Group 1 had higher deposition of seeds, however, the lowest densities for the SB and SeB, which is correlated with a decrease in slope. The highest values in SR, SB and SeB were observed in Group 2, with the highest level of anthropogenic interference. Group 3, with lower SR and intermediate density for the other mechanisms, had its plots distributed in accordance with the increase in slope. Allophylus edulis (A. St.- Hil., Cambess & A. Juss.) Radlk., Piper xylosteoides Steud. and Piper aduncum L. showed positive correlation with the increase in slope. The population structure of the three species that were studied showed clustered distribution. Araucaria angustifolia, which is an emerging species, showed high density of individuals regenerating in environments with higher levels of alteration. Blepharocalyx salicifolius and Ilex paraguariensis, have distributed themselves predominantly in the upper and middle strata, and have shown higher population stability within the group on more advanced successional stage. Consequently, it is possible to conclude that the groups determine different patterns in forest regeneration and the structure of populations; therefore, they should be considered in case of possible interventions in the ecosystem.<br>A ecologia da regeneração e a dinâmica de populações constituem informações necessárias à conservação e ao manejo dos ecossistemas florestais. Assim, este estudo teve como objetivos caracterizar: a) os mecanismos de regeneração natural em um remanescente de Floresta Ombrófila Mista; e b) a estrutura populacional de Araucaria angustifolia (Bertol.) Kuntze, Blepharocalyx salicifolius (Kunth) O. Berg e Ilex paraguariensis A. St. Hil. Deste modo, utilizou-se a estrutura amostral do projeto PELD/CNPq, instalada na Floresta Nacional de São Francisco de Paula, RS, Brasil, sendo avaliados seis conglomerados (1ha), com 16 parcelas (20 x 20m) cada, desconsiderando 10m de bordadura. Os mecanismos de regeneração avaliados foram chuva de sementes (CS), banco de sementes do solo (BS) e banco de plântulas (BP) (indivíduos com altura ≥ 30cm e diâmetro à altura do peito (DAP) < 1cm). Adicionalmente, para o estudo das populações, considerou-se: a regeneração natural estabelecida (RNE) (1 ≤ DAP < 4,8cm) amostrada em células de 3,16 x 3,16m; a classe de tamanho I (CT I) (4,8 ≤ DAP < 9,55cm) em subparcelas 10 x 10m; e a CT II (DAP ≥ 9,55cm) inventariada nas 96 parcelas de 20 x 20m. Esses dados foram coletados em 2008, sendo mensurados o DAP e a posição sociológica. Os mecanismos de regeneração foram avaliados quanto à composição florística e estrutura horizontal. Além disso, para o BP foi realizada a análise de agrupamento, pelo método TWINSPAN (Two-way Indicator Species Analysis) e análise de correspondência canônica (CCA). A estrutura populacional das três espécies foi analisada pela caracterização da posição sociológica, distribuição espacial e frequência em classes de tamanho. Na CS, foram amostradas 81 espécies, 46 gêneros e 28 famílias, no BS, 103, 65 e 41 e no BP, 88, 57 e 36, respectivamente. A análise pelo TWINSPAN determinou a formação de três grupos no BP, com respectivos históricos de interferência e condições mbientais. A CCA indicou a declividade como variável ambiental com maior influência sobre a distribuição das parcelas e espécies. O Grupo 1 apresentou elevada deposição de diásporos, porém, as menores densidades para o BS e BP, estando correlacionado com a diminuição na declividade. Os maiores valores, na CS, BS e BP foram observados no Grupo 2, com maior nível de interferência antrópica. O Grupo 3, com menor CS e densidade intermediária para os demais mecanismos, teve suas parcelas distribuídas de acordo com o aumento na inclinação do terreno. Allophylus edulis (A. St.-Hil., Cambess & A. Juss.) Radlk., Piper xylosteoides Steud. e Piper aduncum L. apresentaram correlação positiva com o aumento na declividade. A estrutura populacional das três espécies estudadas indicou distribuição espacial agregada. Araucaria angustifolia, espécie emergente, apresentou elevada densidade de indivíduos regenerantes em ambientes com maior nível de alteração. Blepharocalyx salicifolius e Ilex paraguariensis distribuíram-se, predominantemente, nos estratos superior e médio respectivamente, e apresentaram maior estabilidade populacional no grupo em estádio sucessional mais avançado. Pelo exposto, concluí-se que os agrupamentos determinam padrões diferenciados, na regeneração da floresta e na estrutura das populações, devendo ser considerados em caso de possíveis intervenções no ecossistema.

Three species of woody plants, Ilex crenata 'Helleri', Juniperus chinensis procumbens 'Nana', and Ligustrum lucidum, were grown in one-liter containers filled with pine bark to determine Fe and Mn requirements with regard to rate and ratio. FeEDTA and MnEDTA were applied at either a 2:1 or 1:2 ratio of Fe:Mn at 5 concentrations each, 3 times per week with each irrigation. Medium solutions were collected every 21 days on one species and analyzed for Fe and Mn levels. Dry weight and tissue Fe and Mn levels were determined for all three species. Neither rate nor ratio of applied Fe and Mn had an effect on shoot dry weights. Control treatments, in general, had the lowest medium solution and tissue levels of Fe and Mn, however, there was no difference in dry weights between control and treatment plants. These results suggest that pine bark supplies adequate levels of Fe and Mn for growth under the conditions of this study. In a second study, three sources of Fe and Mn were applied to Tagetes erecta 'Inca' growing in 500 cc plastic pots containing sieved pine bark at 3 lime rates: 0, 3, and 6 kg m⁻³. Sources of Fe and Mn were pre-plant Micromax, liquid sulfate salts, and liquid chelates applied in the irrigation water. No difference in growth between micronutrient sources was detected, however, growth was greater at the 3 and 6 kg m⁻³ lime rates. Levels of Fe and Mn in medium solution and tissue decreased with increasing lime rate, with availability of Fe and Mn greatest with chelate as the source, regardless of lime rate. A similar study was conducted with a control and liquid sulfate treatment. There was no difference in dry weight between the sulfate treatment and the control, except at 0 kg m⁻³ lime where the control plants were larger. Again, lime additions increased growth, and Fe and Mn availability in medium solution and tissue levels decreased. These results suggest that if Fe and Mn additions are needed, all sources provide adequate Fe and Mn for growth.<br>M.S.

Made available in DSpace on 2014-06-11T19:30:20Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-08-09Bitstream added on 2014-06-13T19:39:48Z : No. of bitstreams: 1 camara_atr_me_botfca.pdf: 536810 bytes, checksum: 57f5286522d61f84e18be56157805a7d (MD5)<br>Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)<br>Sementes recalcitrantes sempre apresentam dificuldades em seu armazenamento, tornandose um problema para produtores de mudas que muitas vezes não têm como realizar a semeadura logo após a colheita das sementes ou necessitam produzir mudas em diferentes épocas do ano, além de dificultar a conservação de germoplasma. As sementes de ingá, depois de colhidas, perdem sua viabilidade rapidamente, geralmente não ultrapassando 15 dias. As espécies de sementes recalcitrantes normalmente não utilizam bancos de sementes como estratégia de regeneração em condições naturais. Observações ecológicas têm mostrado que é mais comum sua regeneração natural ser por meio de bancos de plântulas. O objetivo do trabalho foi avaliar o armazenamento de sementes pré-germinadas de Inga vera Willd., provenientes de frutos em dois estádios diferentes de maturação, em três condições diferentes de umidade de substrato e em baixa temperatura. Os frutos de Inga vera Willd. colhidos foram separados em duas categorias, de acordo com sua coloração de casca, entre verdes e maduros. Após seu beneficiamento, as sementes foram prégerminadas e armazenadas em substrato sem adição de água (testemunha), com 30 e 60% de umidade sob baixa temperatura (10°C), por um ano. O armazenamento feito a 30 e 60% de umidade mostrou-se com melhor eficiência, tanto para plântulas provenientes de frutos verdes, como as de frutos maduros. Entre os dois tipos de frutos, observou-se que as plântulas obtidas de vagem verde, obtiveram melhor desempenho sob as condições de armazenamento, em relação àquelas obtidas de vagem madura. Podem ser armazenadas por até quatro meses, mantendo 50% de sobrevivência das plântulas do lote, quando o armazenamento é feito sob baixa temperatura (10 ± 5°C) e em substrato com 30 e 60% de umidade. Após um período de armazenamento...<br>Recalcitrant seeds always present difficulties for storage procedures, becoming a problem for seedling producers that often have no choice to sow them immediately after seed harvest or when they need to produce seedlings through different times by the year. Inga seeds, once harvested, lose quickly their viability, often not exceeding a period of 15 days. Species of recalcitrant seeds do not use seed banks as regeneration strategy into the natural environment. Ecological observations have shown that is common occur their natural regeneration through seedling banks. The objective of this work was to evaluate pregerminated seed storage of Inga vera Willd. from two fruit maturation stages, under different conditions of substrate humidity, and under low temperature. The collected fruits of I. vera 9were splited into two types, according to their color, between unripe and ripe. After the processing of those seeds, they were pre-germinated on substrate and stored in substrate with no water addition (control), 30, and 60% humidity under low temperature (10°C) for a year. The storage made under 30 and 60% humidity showed to be the best for both, seedlings from unripe and ripe fruits. Between two types of fruits, we observed that the seedlings from unripe fruits, presented better performance under storage conditions, when compared to those obtained from mature fruits. They can be stored for until four months, with 50% of seedling survivals when stored under low temperature (10 ± 5°C) and with 30 and 60% of substrate humidity. After a year of seedling storage it was possible to get until 10% of survival... (Complete abstract click electronic access below)

Studies of seed dynamics and seedling establishment at the community level in savanna ecosystems are scant, particularly in the tropical savannas of Central Brazil. The Brazilian savannas (cerrado) have the largest diversity of plant species among Neotropical savannas. Cerrado vegetation exhibits consistent changes in tree density and tree size along shallow topographic gradients. Vegetation types differ from closed savannas with high tree density, and a nearly continuous canopy cover in the uppermost portions, to open savannas with scattered short trees in the low portions of the topographic gradients. Whether or not dynamics of seeds and seedlings of woody species are consistent with variations in tree density and tree canopy cover across the cerrado landscape has not been determined, but could potentially influence such spatial patterns of tree density and canopy cover. The main objective of this study was to evaluate seed dynamics (i.e., seed rain, soil seed banks, and seed characteristics) and seedling establishment of woody species in three major cerrado vegetation types (closed, intermediate and open savannas) which differ in tree canopy cover and tree height. These vegetation types are located along topographic gradients of approximately 30 m in elevation and 1000 m in length. I conducted field work from June 2005 to August 2008 at the Instituto Brasileiro de Geografia e Estatística (IBGE) reserve, a field experimental station located 35 Km south of Brasilia, Brazil (15˚ 56' S, 47˚ 63' W, altitude 1100 m). I established permanent plots in each of the three vegetation types to assess seed rain, seed limitation, seed predation, and seed removal. I also quantified density and composition of the soil seed bank in each vegetation type and studied seed characteristics (i.e., kind of dormancy, moisture content, longevity) of 14 common cerrado woody species. In the field, I quantified establishment of woody seedlings in fire-protected savannas as well as in accidentally burned and frequently burned savannas. In the greenhouse I performed experiments to evaluate the effect of litter cover and light level on seedling emergence of 9 common cerrado woody species. Finally, I evaluated the effect of pulses of heat on seed germination of 5 common cerrado woody species under controlled conditions. The overall results of this study show that regardless of tree canopy cover, cerrado vegetation types are limited in seeds and seedlings of woody species, but these limitations are higher in open than in closed savannas. Most woody species do not form persistent soil seed banks along cerrado vegetation types because their seeds are short-lived, predated and quickly removed from the ground. In addition, dispersal season and dormancy appear to control timing of germination at the onset of the rainy season to ensure survival of seedlings in the field. In the absence of fire, establishment of woody seedlings is higher in closed than in open savannas because canopy cover mitigates the stressful environmental conditions of open savannas and thus facilitates establishment of woody seedlings. As a result, closed savannas are likely to maintain higher density of woody elements over time than open savannas. In burned savannas, however, species composition of woody and herbaceous seedlings is significantly affected because establishment of seedlings of woody and herbaceous species decreases but vegetative reproduction increases. This dissertation study indicates that interactions of early life-history stages of woody species with environmental and disturbance factors appear to play a more significant role in maintaining woody cover variations along cerrado topographic gradients than previously recognized.

Orientador: Edson Seizo Mori<br>Banca: Marcia Balistiero Figliolia<br>Banca: Edvaldo Aparecido Amaral da Silva<br>Resumo: Sementes recalcitrantes sempre apresentam dificuldades em seu armazenamento, tornandose um problema para produtores de mudas que muitas vezes não têm como realizar a semeadura logo após a colheita das sementes ou necessitam produzir mudas em diferentes épocas do ano, além de dificultar a conservação de germoplasma. As sementes de ingá, depois de colhidas, perdem sua viabilidade rapidamente, geralmente não ultrapassando 15 dias. As espécies de sementes recalcitrantes normalmente não utilizam bancos de sementes como estratégia de regeneração em condições naturais. Observações ecológicas têm mostrado que é mais comum sua regeneração natural ser por meio de bancos de plântulas. O objetivo do trabalho foi avaliar o armazenamento de sementes pré-germinadas de Inga vera Willd., provenientes de frutos em dois estádios diferentes de maturação, em três condições diferentes de umidade de substrato e em baixa temperatura. Os frutos de Inga vera Willd. colhidos foram separados em duas categorias, de acordo com sua coloração de casca, entre verdes e maduros. Após seu beneficiamento, as sementes foram prégerminadas e armazenadas em substrato sem adição de água (testemunha), com 30 e 60% de umidade sob baixa temperatura (10°C), por um ano. O armazenamento feito a 30 e 60% de umidade mostrou-se com melhor eficiência, tanto para plântulas provenientes de frutos verdes, como as de frutos maduros. Entre os dois tipos de frutos, observou-se que as plântulas obtidas de vagem verde, obtiveram melhor desempenho sob as condições de armazenamento, em relação àquelas obtidas de vagem madura. Podem ser armazenadas por até quatro meses, mantendo 50% de sobrevivência das plântulas do lote, quando o armazenamento é feito sob baixa temperatura (10 ± 5°C) e em substrato com 30 e 60% de umidade. Após um período de armazenamento... (Resumo completo, clicar acesso eletrônico abaixo)<br>Abstract: Recalcitrant seeds always present difficulties for storage procedures, becoming a problem for seedling producers that often have no choice to sow them immediately after seed harvest or when they need to produce seedlings through different times by the year. Inga seeds, once harvested, lose quickly their viability, often not exceeding a period of 15 days. Species of recalcitrant seeds do not use seed banks as regeneration strategy into the natural environment. Ecological observations have shown that is common occur their natural regeneration through seedling banks. The objective of this work was to evaluate pregerminated seed storage of Inga vera Willd. from two fruit maturation stages, under different conditions of substrate humidity, and under low temperature. The collected fruits of I. vera 9were splited into two types, according to their color, between unripe and ripe. After the processing of those seeds, they were pre-germinated on substrate and stored in substrate with no water addition (control), 30, and 60% humidity under low temperature (10°C) for a year. The storage made under 30 and 60% humidity showed to be the best for both, seedlings from unripe and ripe fruits. Between two types of fruits, we observed that the seedlings from unripe fruits, presented better performance under storage conditions, when compared to those obtained from mature fruits. They can be stored for until four months, with 50% of seedling survivals when stored under low temperature (10 ± 5°C) and with 30 and 60% of substrate humidity. After a year of seedling storage it was possible to get until 10% of survival... (Complete abstract click electronic access below)<br>Mestre

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior<br>This study evaluated the mechanisms of natural regeneration represented by seeds rain, seeds bank of the soil and the regeneration vegetation, considering the seedlings bank and the established regeneration, in a fragment of Estacional Decidual Forest. The evaluation was made with 70 randomized samplings in 14 parcels inside four bands, with systematic distribution in the area. The seeds rain was studied using 70 collectors with 1 m x 1 m, the collected material was analyzed monthly, during a year. In the seeds bank was collect 70 samplings using an iron collector (25 x 25 cm) on the soil surface and adjusting the studied samplings to 5 cm of deep. The collected material was taken to the Laboratory of Silvicultura of the Departament of Ciências Florestais of the Federal University of Santa Maria, where it was evaluated during seven months. The seeds bank was evaluated in 70 sampling units of 2 x 2 m where was identified and measured all plants with h ≥ 30 cm and DBH < 1 cm, the natural regeneration in the area was evaluated in 70 sampling units of 5 x 5 m, in which were identified and measured all plants with 1cm ≤ DBH ≤ 5 cm. The regeneration mechanisms were analyzed in groups formed in the adult vegetation. In the seeds rain it was observed the presence of 73 species, mainly trees. The seeds bank of the soil show predominance of herbaceous species, and some trees and bush-like species, pioneer species and secondary species. In the seedlings bank, was observed the presence of light demanding tree species and eciofiles species, while in the established natural regeneration the predominance was of shadow species. The seed bank of the soil and the established natural regeneration show different comportment for the group 1 and 2 in the adult vegetation, while the seeds rain and seedlings bank show uniformity in the forest. The species with the bigger probability to perpetuate in the studied forest reminiscent and in the near areas were Gymnanthes concolor, Soroceae bonplandii, Eugenia rostrifolia, Trichilia claussenii, Trichilia elegans, Myrocarpus frondosus, Cupania vernalis, Nectandra megapotamica and Dasyphylum spinescens, these species can be used to enrichment and recuperation of the forest. The most restricted species were Cordia tricotoma, Luehea divaricata, Sebastiania commersoniana and Syagrus rommanzoffiana, these species may grow in the forest if used the right treatments to their perpetuation. The indicative species in the adult vegetation groups have the seeds rain and the seedlings bank as the main mechanisms for their conservation in the forest reminiscent.<br>Este estudo avaliou os mecanismos de regeneração natural, representada pela chuva de sementes, banco de sementes do solo, e vegetação em regeneração, considerando banco de plântulas e regeneração natural estabelecida, em remanescente de Floresta Estacional Decidual. A avaliação foi realizada em 70 subparcelas, aleatorizadas em 14 parcelas, dentro de 4 faixas distribuídas sistematicamente, na área. A chuva de sementes foi estudada em 70 coletores de 1 m x 1 m, cujo material era coletado mensalmente para avaliação, no curso de um ano. No banco de sementes do solo foram coletados 70 amostras, a partir de um gabarito de ferro (25 x 25 cm), que colocado sob a superfície do solo permitia a padronização da área para coleta em 5 cm de profundidade. O material coletado foi levado para o Laboratório de Silvicultura do Departamento de Ciência Florestais da Universidade Federal de Santa Maria, onde foi avaliado durante 7 meses. O banco de plântulas foi avaliado em 70 unidades amostrais de 2 x 2 m, onde identificaram-se e mediram-se todos os indivíduos com h ≥ 30 cm e DAP < 1 cm. A regeneração natural estabelecida foi avaliada em 70 unidades amostrais de 5 x 5 m. Nestas, identificaram-se e mediram-se todos os indivíduos com 1cm ≤ DAP < 5 cm. Os mecanismos de regeneração foram analisados em agrupamentos, formados na vegetação adulta. Na chuva de sementes, observou-se a presença de 73 espécies, principalmente, arbóreas. O banco de sementes do solo teve predomínio de espécies herbáceas, além de arbóreas e arbustivas, espécies pioneiras e secundárias iniciais. No banco de plântulas observou-se a presença de espécies heliófilas e eciófilas, enquanto na regeneração natural estabelecida foi verificado o predomínio de espécies de sombra. O banco de sementes do solo e a regeneração natural estabelecida apresentaram comportamento diferente para o grupo 1 e 2 da vegetação adulta, enquanto a chuva de sementes e banco de plântulas apresentaram uniformidade na floresta. As espécies com maior potencialidade para perpetuar no remanescente de floresta estudado foram Gymnanthes concolor, Soroceae bonplandii, Eugenia rostrifolia, Trichilia claussenii, Trichilia elegans e Dasyphylum spinescens, sendo indicadas para enriquecimento. As espécies com maior restrição, foram Cordia tricotoma, Myrocarpus frondosus, Cupania vernalis, Nectandra megapotamica, Luehea divaricata, Sebastiania commersoniana e Syagrus rommanzoffiana, dependendo de tratamentos silviculturais na floresta para garantir sua perpetuação. As espécies indicadoras dos agrupamentos, na vegetação adulta, têm a chuva de sementes e banco de plântulas como principais mecanismos de conservação das espécies no remanescente.

Submitted by Deyse Queiroz (deysequeirozz@hotmail.com) on 2018-06-13T12:15:00Z No. of bitstreams: 1 MARIA DO SOCORRO ROCHA - DISSERTAÇÃO PPGEA 2004..pdf: 12014866 bytes, checksum: e5b21eb998760e2ed7cd6bdeddf94a3e (MD5)<br>Made available in DSpace on 2018-06-13T12:15:00Z (GMT). No. of bitstreams: 1 MARIA DO SOCORRO ROCHA - DISSERTAÇÃO PPGEA 2004..pdf: 12014866 bytes, checksum: e5b21eb998760e2ed7cd6bdeddf94a3e (MD5) Previous issue date: 2004-11<br>A conservação e manipulação dos recursos genéticos vegetais de espécies de valor económico são de fundamental importância para a conservação em banco de germoplasma. Este trabalho teve como objetivo; a) avaliar a crioconservação de sementes de algodão das cultivares BRS-Verde, BRS-200, BRS-187-8H e 6MMocó e b) estudar a indução ao superbrotamento dos nós cotiledonares de plântulas do algodoeiro cultivados in vitro, para as mesmas cultivares supracitadas. Neste trabalho propôs-se inicialmente determinar do teor de água limite para crioconservação (TALC). Para esta determinação as sementes foram imersas ao nitrogénio líquido (-196°C) por cinco dias e após esse período elas forma descongelados e submetidas ao teste de germinação e vigor. Utilizou as armazenagem das sementes a 23°C por 5 dias como testemunha. O delineamento estatístico empregado foi o inteiramente casualizado com arranjo fatorial representado por (quatro cultivares x duas temperaturas x seis teor de água). Na crioconservação utilizou-se um lote de sementes com teor de água limite previamente determinado para as diferentes cultivares, a partir do qual se procedeu ao seu armazenamento em nitrogénio líquido (-196°C) e no vapor do nitrogénio (-170°C), durante 5, 30, 60 e 90 dias. O delineamento experimental utilizado nesta etapa foi o inteiramente casualizado em parcela sub-dividida no tempo, sendo a parcela representas pela interação (quatro cultivares x duas temperaturas de armazenamento) e a sub-parcela pelos quatro períodos de armazenamento. Em cada período de armazenamento, as sementes foram submetidas a testes de germinação e vigor. De acordo com os resultados obtidos póde-se concluir que: a) estudar a determinação do teor de água limite para crioconservação-TALC, durante 5 dias, o teor de água limite para a crioconservação das cultivares BRS-Verde, BRS-200, 6M-Mocó e BRS-187-8H considerando-se a germinação dessas cultivares está entre 6 e 8% (b.u.) e considerando-se o vigor das sementes o TALC é de 6% (b.u.); b) sementes de algodoeiro, das diferentes cultivares podem ser crioconservados em banco de germoplasma nas duas temperaturas, ou seja no vapor a -170°C ou imersa ao nitrogénio líquido a -196°C; c) a crioconservação aumenta o percentual de germinação e vigor das sementes de algodão, devido a essa temperatura a promover uma quebra de dormência pela ação do frio. No Capítulo II propôs-se a indução de superbrotamento, empregando como explante dos nós cotiledonares, plântulas cultivadas in vitro durante 25 dias. Os explantes foram cultivados em tubos de ensaio contendo o meio básico MS, suplementado com citocininas BAP, KIN e TDZ, isolados ou associados em diferentes concentrações. Os tubos de ensaio contendo os explantes foram mantidos em sala de crescimento regulada à temperatura de 28°C, fotoperíodo de 16/8h (claro/escuro) e intensidade luminosa de 50umol.m2.s1 , durante 40 dias os quais foram avaliados por meio do delineamento inteiramente casualizado, com arranjo fatorial de 4x17 (quatro cultivares x dezessete meios), sendo então avaliadas quanto ao número de brotos emitidos e altura de brotos. De acordo com os resultados obtidos póde-se concluir que: O meio MS suplementados com BAP (2,0 mg.L"1) isolado ou associado com KIN (1,0mg.L"1), promoveu uma maior capacidade de regeneração e altura de brotos; b) o meio MS suplementados com BAP (2,5 mg.L"1) estimulou maior altura de brotos;c)o meio MS suplementados com TDZ (1,0 mg.L"1 , 0,50 mg.L"1e 0,25 mg.L"1) afetou a capacidade de regeneração de brotos, obteve formação de calos.<br>A conservação e manipulação dos recursos genéticos vegetais de espécies de valor económico, são de fundamental importância para a conservação em banco de germoplasma. Este trabalho teve como objetivo: a) avaliar a crioconservação de sementes de algodão das cultivares BRS-Verde, BRS-200- Marrom, BRS-187-8H-Branco e 6 M-Mocó-Branco e b) estudar a indução ao superbrotamento dos nós cotiledonares de plântulas do algodoeiro cultivados in vitro, para as mesmas cultivares supracitadas. Inicialmente, determina-se do teor de água limite para crioconservação (TALC). Para esta determinação, as sementes foram imersas no nitrogénio líquido (-196°C) durante cinco dias e após este período elas foram descongelados e submetidas ao teste de germinação e vigor. Utilizou-se a armazenagem das sementes a 23°C por 5 dias, como testemunha. O delineamento estatístico empregado foi o inteiramente casualizado com arranjo fatorial representado por (quatro cultivares x duas temperaturas x seis teores de água). Na crioconservação utilizou-se um lote de sementes com teor de água limite previamente determinado para as diferentes cultivares, a partir do qual se procedeu ao seu armazenamento em nitrogénio líquido (-196°C) e no vapor do nitrogénio (-170°C), durante 5, 30, 60 e 90 dias. O delineamento experimental usado nesta etapa foi o inteiramente casualizado, em parcela subdividida no tempo, sendo a parcela representada pela interação (quatro cultivares x duas temperaturas de armazenamento) e a subparcela pelos quatro períodos de armazenamento. Em cada período de armazenamento as sementes foram submetidas a testes de germinação e vigor. De acordo com os resultados obtidos concluiu-se que: a) O teor de água limite para crioconservação-TALC, durante 5 dias, para a crioconservação das cultivares BRS-Verde, BRS-200-Marrom, 6MMocó- Branco e BRS-187-8H-Branco, considerando-se a germinação dessas cultivares está entre 6 e 8% (b.u.) e, quanto os vigor das sementes, o TALC foi de 6% (b.u.); b) sementes de algodoeiro das diferentes cultivares podem ser crioconservadas em banco de germoplasma, nas duas temperaturas, ou seja, no vapor a -170°C ou imersa ao nitrogénio líquido a -196°C; c) a crioconservação aumenta o percentual de germinação e vigor das sementes de algodão, em virtude dessa temperatura promover quebra de dormência, pela ação do frio. No Capítulo II propôs-se a indução de superbrotamento, empregando-se como explante nós cotiledonares de plântulas cultivadas in vitro durante 25 dias. Os explantes foram inoculados em tubos de ensaio contendo o meio básico MS, suplementado com citocininas BAP, KIN e TDZ, isolados ou associados a diferentes concentrações. Os tubos de ensaio contendo os explantes foram mantidos em sala de crescimento regulada à temperatura de 28°C, fotoperíodo de 16/8h (claro/escuro) e intensidade luminosa de 50umol.m2.s1 , durante 40 dias, os quais foram avaliados por meio do delineamento inteiramente casualizado, com arranjo fatorial de 4x17 (quatro cultivares x dezessete meios), sendo então avaliadas quanto ao número de brotos emitidos e altura do comprimento de brotos. De acordo com os resultados obtidos pôde-se concluir que: a) o meio MS suplementado com BAP (2,0mg.L~1) isolado ou associado a KIN (1,0mg.L~1), promoveu maior capacidade de regeneração e altura de brotos; b) o meio MS suplementado com BAP(2,5mg.L"1 ) estimulou altura superior de brotos; c) o meio MS suplementado com TDZ (1,0mg.L~1, 0,50mg.L"1 e 0,25mg.L"1) afetou a capacidade de regeneração de brotos e a formação de calos.

Despite its long tradition in our country, livestock grazing almost disappeared from Czech landscape. This form of land use has winded down in the middle of 20th century, when compulsory co-operative farming was introduced. Decrease of pasturage is especially visible on fragmented areas of steep slopes and in dry places. These areas are often highly valuable and protected for its nature richness. When a grazing management is introduced, its effects on plant species communities are not clear. Also the exact mechanisms of vegetation changes caused by grazing are often unknown. In 2005, administration of PLA Český kras reinstated grazing management as a mean of preservation of dry grassland ecosystems. As part of this project I studied, how generative regeneration contributes to vegetation changes. The aim of the present study is to ascertain: a) how is seedling recruitment and survival affected by grazing, b) what are limitations of generative reproduction, and c) what is the contribution of soil seed bank to vegetation changes. In 2005, monitoring of seedling recruitment and survival had started, repetitive sowing experiment was performed and species composition of persistent seed bank was analyzed. Grazing had a positive effect on seedling - both numbers of seedling and their species composition....

Integrating cultural weed management practices with herbicides is an important strategy to reduce wild oat (Avena fatua L.) populations in Alberta, Canada. The purpose of this thesis is to expand the knowledge on wild oat seed banks and seedling emergence within integrated weed management systems. Field experiments were conducted from 2006-2007 to examine the impact of crop rotation, barley cultivar, barley seeding rate and herbicide rate on wild oat seed bank density, seed mortality, seedling emergence and seedling survivorship. Management systems consisting of diverse crop rotations, tall barley cultivars and increased barley seeding rates reduced wild oat seed bank density, seedling emergence and seedling survivorship, especially at low herbicide rates. Wild oat seed banks predicted subsequent wild oat emergence, whereas biomass and emergence strongly predicted seed banks. Lastly, 50% wild oat emergence was achieved at 537 and 509 growing degree days in 2006 and 2007, respectively, in Lacombe, Alberta.<br>Plant Science

Thesis (Ph. D.)--University of Georgia, 2006.<br>Directed by Stephen Hubbell. Includes articles submitted to The journal of vegetation science and Journal of ecology. Includes bibliographical references (leaves 77-84).

碩士<br>國立中興大學<br>植物學系<br>89<br>The disturbances at Guandaushi forest ecosystem include earthquake-caused landslides, treefalls and fires. The composition and density of the soil seed bank, and the seedling emergence and morality have been monitored at landslide sites and treefall gaps. A total of 602 seedlings germinated from the collected soil samples. 526 seedlings belonging to 28 families and 48 species have been indentified. The seeds of shade-intolerant species were common in the soil of disturbed sites. The main components of the soil seed bank were Rubus species in disturbed sites. The results of seedling emergence indicated that the amount of remaining topsoil and the stability of newly formed topsoils influenced the density of soil seed bank. The fluctuation of the soil seed density was related to the stability of newly formed topsoil, the seed germination and also the time of disturbance. The composition and density of seedlings in the field plots were surveyed at 2 month intervals from January 2000 to June 2001. Totally 945 seedling were tagged. 885 seedlings belonging to 28 families and 51 species have been indentified. Most seedlings at landslide sites were shade-intolerant species with relatively small seeds that are easily to be dispersed by wind (Crassocephalum rabens, Acer serrulatus, Schima superb, Mallotus paniculatus ) and by birds ( Litsea cubeba ). The main components of the seedlings at treefall gaps were shade-tolerant species of shrub and vine. Seedling density was related to the existence of the original topsoil, the stability of new topsoil and the size of disturbed site. The fluctuation of density and morality of seedlings were also related to the existence of the original topsoil, the stability of new topsoils, the germination of seeds and the growth of seedlings. The fluctuation of the seedling density at treefall gaps was related to seasonal change. The result of DCA suggested that seedling distribution was correlated to slope, elevation and soil stoniness. Most shade-intolerant species were distributed at landslide sites with steep slope and high stoniness . Among the life forms (tree, shrub, vine and herb), seedlings of tree species were more abundant with lower morality. The above results implied that shade-intolerant tree species seem to be more adaptable to landslide sites. The similarity indices of soil seed bank between disturbed sites and adjacent understory were between 19.51% ~ 77.92%. The similarity indices between upper canopy species and understory seedlings were higher than those between upper canopy species and soil seed banks. Results in this study implied that the major source for the regeneration at landslide sites were the seeds of shade-intolerant species which were apart from the disturbed areas. The seedling bank, instead of the soil seed bank, would be the major source for gap regeneration and the recruitment of upper canopy species.

Rapid subsidence and eustatic sea level rise are leading to increased flooding and perpetually waterlogged soils along the Gulf Coast. This study addresses the impact of this environmental change on coastal Louisiana bottomland hardwood forests. I employed a space-for-time substitution to compare seed banks, seedling banks, and seed rain in two sites of different hydroperiod, and to predict how small increase in hydroperiod may affect forested wetland community composition and dynamics Within terrestrial ecosystems, seed banks respond to disturbances by providing individuals for regeneration. In this study the wetter ('swamp') site's seed hank was more dense and species rich than the drier ('ridge') site's. Herbaceous species dominated both sites' seed banks. Tree and shrub seeds were most numerous and species rich in the ridge site, suggesting regeneration of the woody community requires a seed bank like that encountered in drier soils. Thus, as hydroperiod Continue to increase, seed of woody species will become unavailable for disturbance response Like seed banks, seedling hanks are active in disturbance response. While the cumulative number of seedlings censured over two years was equivalent at both sites, the ridge site hod greater seedling density, longer mean seedling lifespan, and greater seedling survivorship. In both sites, woody seedlings were denser and more species rich than herbaceous seedlings. Although a severe drought caused short-term decreases in seedling density, health, and leaf number regardless of site, the expected increase in hydroperiod will have long-term implications Lastly, I used the seed bank, seedling bank, and seed rain data to construct site-specific static life tables for selected woody species and life form groupings. These illustrate how individual species would respond to increases in hydroperiod. While some woody species, including Acer rubrum and Brunnichia ovata, will benefit from more hydric soils, most, including Celtis laevigata and Liquidambar styraciflua, will decline This study indicates that environmental changes already underway will lead to a loss of coastal plain bottomland hardwood forests as communities shift to species adapted to greater hydroperiod. If these trends are allowed t0 continue unabated, an eventual loss of all woody species, and therefore coastal forested wetlands, is expected<br>acase@tulane.edu

The release of the seed eating beetle Sulcobruchus subsuturalis for biological control of Caesalpinia decapetala in South Africa has been ongoing since 2000. This is the first post release evaluation of the efficacy of the agent against the weed. The study assessed the phenology of C. decapetala and S. subsuturalis at two sites and included determining the establishment of the beetle on the target weed at 25 study sites. In addition, the effects of S. subsuturalis on seed densities as well as seed germination and seedling recruitment were examined. Furthermore predation by native ants and attacks by native parasitoids were also examined at two release sites. Mature filled pods were available on the tree from September (spring) to March (summer) when the beetle is expected to be reproductively active. The majority of beetle releases by Working for water took place in summer. However the proportion of beetle infested seeds, which were only recovered inside pods in the tree canopy at study sites, was low (0 to 15.5%). Consequently high seed densities and seedling recruitment were observed in the field. In the laboratory, S. subsuturalis did not lay eggs on buried seeds, however seed infestation levels were generally high. Only 8.3% of the seeds containing adults germinated and 6.3% emerged into seedlings. Of the seeds containing larvae, only 14.6% germinated and 2.1% emerged into seedlings. Thus far, S. subsuturalis has failed to maintain high populations on the target weed, possibly due to egg predation by native ants (Crematogaster species, Pheidole megacephala, Messor natalensis and Tetramorium avium) and attacks by native parasitoids. Egg predation reached 100% within 10 days. Egg parasitism by unknown parasitoids ranged between 80 and 93.1% in Limpopo. The parasitic wasp Dinarmus altifrons was recovered once developing inside a C. decapetala seed infested with S. subsuturalis. Further investigations regarding attacks by indigenous parasitoids on S. subsuturalis are required to determine the extent of this problem. Meanwhile releases of S. subsuturalis against C. decapetala should continue. However release efforts need to be improved by (a) using inundative rather than inoculative releases (b) Releasing every year between September and March (summer) and (c) involving land owners, farmers and nature reserve authorities in release activities. Ultimately an additional agent should be sought for release against C. decapetala as the weed may not be the preferred host for S. subsuturalis.

碩士<br>國立屏東科技大學<br>森林系<br>89<br>Different regeneration strategies for forest plants will effect the future succession of forest community. It is helpful to understand the dynamics of the forest by investigating the various regeneration methods of plants. The soil seed bank is one of the important regeneration strategies. Through this research of 1 ha area of research site, we try to check the composition of the soil seed bank in the broadleaf-coniferous forest of Dona, and investigate the responses of growth and physiology in three different light environments using Litsea cubeba, Eurya nitida var. nitida and Cycolbalanopsis longinux as materials. The Dona forest were dominated by Castanopsis carlesii、Pseudotsuga wilsoniana、Illicium tashiroi、Cyclobalanopsis longinux and Machilus thunbergii. The J shape of diameter structure of Pseudotsuga wilsoniana reveals this specie can not regenerate in this forest. Another species of dominant species in Dona forest present opposite J shape of diameter structure and can regenerate continuously by forming a lot of seedlings. The soil seed band is dominated by pioneer species, including 15 species、716 seedlings of pioneers and 1 species、11 seedlings of late successional plants. Both shows outstanding different. The soil seed bank has a higher proportion of herbs and shrubs, being 7.4% and 81% of all germinated seeds respectively, including Litsea cubeba、Rubus linearifolius and Eurya nitida var. nitida. Eurya nitida var. nitida has 1129 germinated seeds, involves 52% of all germinated seeds and spreads from 0-30 cm of soil. Machilus thunbergii and Eurya nitida var. nitida of Dona forest were the only species appearing in the soil seeds bank. But Machilus thunbergii is produced in this year and may germinate soon to form seedling bank. So the regeneration strategy of the dominant plants of late successional forest is not from the soil seed bank. This research try to compare the difference of germinated soil numbers of soil seed bank between gap and understory environment of forest in man-made forest. It reveals the numbers of gap environment is 2.6 times to the ones of understory environment. So gap environment can advance the germination of seeds in soil seed bank. The various microenvironments in the forest, especially the light environment, have a severe impacts on the growth and survival of different successional seedlings.In the research environment of high light , gap and understory, the Amax and relative growth rate of tree height per month in Litsea cubeba is obvious higher than the other species in high light environment, being 8.7 μmol m-2s-1and 18.6%, respectively. It is obvious higher than Cyclobalanopsis longinux, being 6.6μmol m-2s-1 and 2.2%. It shows Litsea cubeba can grow well, and utilize light resources efficiently in a high light environment. However, the dark respiration, light saturation point, and maximum photosynthetic rate of Litsea cubeba and Cycolbalanopsis longinux has no conspicuous difference. The result reveals that Cycolbalanopsis longinux has no better physiological characteristics in understory of the forest, but could have other advantageous mechanisms for flourishing growth and development. The relative growth rate of Eurya nitida var. nitida in tree height is 18.8% in high light environment, and do not differs significantly from Litsea cubeba. In the understory of forest, the dark respiration and light saturation point of Eurya nitida var. nitida are lower than the other species, but the photosynthesis is higher significantly. These characteristics can enhance survival rate of Eurya nitida var. nitida. These representations indicate that Eurya nitida var. nitida can grow well in the understory of forest or in a full light environment. The outcome shows that changes in light from gap formation will be beneficial for the growth and survival of different successional species. Keyword: soil seed bank, photosynthesis, pioneer species, Shade tolerant species

This thesis is focused on environmental preferences of wood-decaying fungi and their relationships with forest structure and development. Relationships of fungi to properties of wood and forest stands were studied on the basis of field observations in Central-European mountain spruce forests. Plot-based approach was used to reveal a general pattern in the diversity of fungi within a single forest stand and between different stands. The analysis of stand structure provided a background for plot-based approach. Substrate-based approach was used to study single species preferences and their communities. In addition, the influence of wood properties (including fungi and their rots) on the regeneration of spruce on logs was studied.