Rivercane, Arundinaria gigantea, is the native woody evergreen grass that has exhibited rapid population decline since European colonization of North America. Agriculture and urban expansion have reduced this important ecosystem type to remnant populations. This poses challenges to current restoration efforts by minimizing genetic diversity and limiting healthy host sites for propagation. Objectives of this research were to test four methods of establishment that would promote the greatest survivability and growth of propagules. Non-irrigated field studies indicated greatest rivercane growth response when planted in increased shade (60 - 85% light reduction). Monthly plantings indicated that February offered the greatest probability of survival. Application of slow release 19-6-12 fertilizer (33.3 g) enhanced growth, but fertilizer applications are not recommended without adequate soil moisture. Halosulfuron (72.6 g a.i./ha) applications for weed control showed no damage to rivercane plants compared to control.

Sorghum (Sorghum bicolor) has the potential to be used as a cellulosic feedstock for ethanol production due to its diversity and wide adaptation to many different climates. With a wide range of diversity, this crop could be tailored specifically for use as a feedstock for ethanol production. Other factors such as water use efficiency, drought tolerance, yield potential, composition, and established production systems also make sorghum a logical choice as a feedstock for bioenergy production. The objectives of this study were to better understand the biomass potential of different types of sorghum that may be used for energy production, and determine the composition of these sorghums over the season to better understand biomass yield and composition over time. Six commercial sorghum cultivars or hybrids that represent sorghum types from grain to energy were evaluated near College Station, Texas during the 2008 and 2009 cropping years. An optimal harvest window (defined by maximum yield) was established for all genotypes, and significant variation was seen among the genotypes for fresh and dry biomass production. The later maturity genotypes, including the photo-period sensitive and modified photo-period sensitive type sorghums, produced the highest yields (up to 24 dry Mg/ha). Compositional analysis using near infrared reflectance spectroscopy (NIR) for lignin, hemicellulose, and cellulose was performed on a dry matter basis for the optimal harvest window for each genotype. Significant differences were seen in 2009 between the genotypes for lignin, hemicellulose, cellulose, ash and protein; with the earlier genotypes having higher percentage of lignin, and the later genotypes having lower percentages of lignin. Genotype x Environment interactions were also seen, and show the significance that rainfall can have. Based on this research, grain sorghum could be harvested first, followed by photo-period insensitive forage varieties, then moderately photo-period sensitive forage varieties followed by dedicated bioenergy sorghums (that are full photo-period sensitive), allowing for a more constant supply of feedstock to processing plants. Sweet sorghums would also allow the end user to obtain biomass when needed, however these types of sorghum may be much better suited to a different end application (i.e. crushing the stalks to obtain the juice).

Cover crops are widely planted in the mid-Atlantic region for their environmental and agronomic benefits, but incomplete or delayed termination can lead to cover crops becoming weeds in the subsequent cash crop, known as volunteers. Studies were conducted from 2020-2022 to evaluate the effect of four commonly grown cover crop species, winter wheat (Triticum aestivum L.), cereal rye (Secale cereal L.), hairy vetch (Vicia villosa Roth), and rapeseed (Brassica napus L.), and four termination timings; 28, 14, 5, and 1 days before corn planting (DBP). Results indicated volunteerism was only an issue with rapeseed. Delaying rapeseed termination resulted in 0, 5, 12, and 22 volunteer plants m-2 at 28, 14, 5, and 1 DBP in corn. In order to manage these rapeseed volunteers, herbicide evaluations were conducted and indicated that atrazine, isoxaflutole, metribuzin, and pyroxasulfone resulted in 92-94% control when applied preemergence. Similarly, atrazine and glyphosate provided 99% rapeseed control and glufosinate resulted in 89% control when applied postemergence. Therefore, volunteers can easily be controlled with commonly used herbicides in corn. Studies were also conducted to evaluate the benefits of these cover crops, which have the potential to overcome the aforementioned risks. Results indicate that hairy vetch produced the most biomass and provided greater control of summer annual grasses, small-seeded broadleaf and large-seeded broadleaf weeds than other cover crops. Biomass accumulation and extent of weed control increased with delaying cover crop termination. Corn yield was greatest following hairy vetch and was least in rapeseed plots. Termination of cover crops 14 DBP planting increased corn yield by 12%; whereas termination at 1 DBP decreased corn yield by 15% as compared to no cover crop-no till plots. Effective termination of cover crops is an important management consideration and information on termination efficiency can help in devising management plans. In order to assist managers by evaluating cover crop termination efficiency, studies were conducted to evaluate selective and non-selective herbicides and a roller crimper for correlating vegetative indices with visible termination efficiency. Among vegetative indices, the Green Leaf Index had the highest Pearson correlation coefficient for wheat (r = -0.79, p = <0.0001) and cereal rye (r = -0.80, p = <0.0001) with visible termination efficiency. Whereas, for rapeseed, Normalized Difference Vegetation Index (NDVI) had the highest correlation coefficient (r = -0.66, p = <0.0001). However, for hairy vetch none of the vegetative indices correlated significantly with visible termination efficiency. While further research is necessary, remote sensing technologies may help in devising management plans by increasing crop scouting efficiency. / Master of Science in Life Sciences / Cover crops reduce soil erosion, leaching of soil nutrients in the water bodies, and provide benefits like weed suppression and improving the cash crop yield. Cover crops are generally planted in fall after the harvest of cash crop and are killed (terminated) before or after planting of next cash crop in the spring. Cover crop plants can also become weedy when they grow as volunteer plants in cash crops and if not terminated effectively. Therefore, effective termination of cover crops is also an important management consideration. Keeping these aspects in view, field experiments were conducted to evaluate different cover crops, winter wheat, cereal rye, hairy vetch, and rapeseed and four termination timings, 28, 14, 5, and 1 days before corn planting (DBP) for biomass accumulation, weed control, and impact on corn yield. Among cover crops, hairy vetch was found to be the best in terms of biomass production, weed control, and improving corn yield, whereas rapeseed had least biomass accumulation and reduced corn yield. Among termination timing, 1 and 5 DBP resulted in the most biomass production and weed control, but corn yield was greatest when terminated at 14 DBP. Delaying rapeseed termination from 28 DBP to 14, 5, and 1 DBP increased volunteer rapeseed in corn by 5, 12, and 22 plants m-2. Preemergence (PRE) and postemergence (POST) herbicides were evaluated for volunteer rapeseed control in corn. Among preemergence (PRE) herbicides, mesotrione, rimsulfuron and flumioxazin provided more than 95% volunteer rapeseed control, whereas atrazine, isoxaflutole, metribuzin, and pyroxasulfone provided 92-94% control. Among postemergence (POST) herbicides, atrazine and glyphosate provided 99% visible control of rapeseed, followed by glufosinate (89%). Various selective and non-selective herbicides were also evaluated for the termination of wheat, cereal rye, hairy vetch, and rapeseed. Non-selective herbicides like glyphosate, glufosinate and paraquat were found more effective for termination of cover crops as compared to non-selective herbicides. Vegetative indices (VI) were evaluated and correlated with visible termination efficiency (ground truth data) and found that VI can be used for estimating termination efficiency and these estimates can help in devising plans for management operations. Among VI, Green Leaf Index had the highest correlation coefficient for wheat and cereal rye visible termination ratings. Whereas for rapeseed, Normalized Difference Vegetation Index (NDVI) had the highest correlation coefficient value. However, for hairy vetch none of the vegetative indices correlated significantly with visible termination efficiency. Overall, hairy vetch was found to be the best cover crop for biomass accumulation, weed control and corn yield improvement. Delayed termination of rapeseed plants resulted in infestation of volunteer rapeseed in corn and reduced corn yield. However, volunteer rapeseed plants can be effectively managed by effective termination and use of proper PRE and POST herbicides in corn. Furthermore, remote sensing-based VIs have shown potential to estimate cover crop termination efficiency.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The impact arising from livestock activity in grassland ecosystems reflects a long history of how this activity was carried. One alternative of lasting management for conservation of these lands is to use the capacity of resilience of natural grassland, in which important tools for recovery are control of leaf defoliation and nutrient replacement. Changes in vegetation take place throughout time and space by a broad range of factors and, for their interpretation, plant s mechanisms of capture and storage of resources must be understood. Plant functional types are one approach highlighted at large scale responses. However to make this framework operational, it depends on knowledge of species development and especially their role in biomass production or in ecological processes at the landscape level. This work s hypothesis is that communities ranked into functional groups of plants may show patterns of biomass distribution along the community that are related to environmental factors and management. The experiment was conducted in livestock farms (UEPAs) enrolled in a project linked to EMBRAPA-CPPSUL established since 2008. In such UEPAs rotational grazing and natural fertilizers were applied together in natural grassland paddocks. Four surveys were conducted for assessment of species contribution on biomass since April/2012 to September/2011. Poaceae species were ranked according to its contribution in vegetation, through their morphological traits: specific leaf area and leaf dry matter content. This approach allows defining groups of species with different features even for large-scale environmental factors . Through biomass accumulation of plant groups with similar functional traits it was possible to diagnose vegetation patterns in response to environmental and management factors. / O impacto decorrente da atividade pecuária em ecossistemas campestres reflete um longo histórico da forma como essa atividade foi exercida. Para manutenção dessas áreas, uma alternativa de manejo durável é usar a capacidade de resiliência da pastagem natural, onde são partes importantes na recuperação: o controle da desfolha e a reposição de nutrientes. Mudanças na vegetação ocorrem ao longo do tempo e do espaço por uma ampla extensão de fatores e para a sua interpretação devem ser entendidos os mecanismos de captura e estocagem de recursos efetuados pela planta. A abordagem de tipos funcionais de plantas é destacada nas respostas em ampla escala, no entanto tornar esse conhecimento um quadro mais operacional depende do conhecimento do desenvolvimento das espécies e sobre tudo sua implicação na produção ou nos processos ecológicos em nível de pastagem. A hipótese deste trabalho é que as comunidades classificadas em grupos funcionais de plantas possam demonstrar padrões de configurações de biomassa na comunidade que se relacionam a fatores ambientais e de manejo. Este estudo foi realizado em estabelecimentos rurais (UEPAs) cadastradas em projeto vinculado a EMBRAPA-CPPSUL implantado a partir do ano de 2008. Nessas UEPAs foram realizados quatro inventários para determinação da composição botânica e contribuição das espécies na massa de forragem, no período de setembro/2011 a abril/2012. O manejo do pastoreio foi o rotativo e a pastagem natural recebeu aplicação de fertilizantes naturais. Na abordagem foram classificadas as espécies de Poaceae que possuem maior participação na vegetação, através de seus atributos morfológicos TMS e AFE, possibilitando agrupar espécies com diferentes características em diferentes condições ambientais. Através do acúmulo de biomassa nas comunidades de grupos de plantas com atributos funcionais semelhantes foi possível diagnosticar padrões de vegetação em resposta aos fatores ambientais e de manejo.

Biomes classified as Brazilian Atlantic Forest (BAF) and the Chilean Mediterranean forest (CMF) have been affected by anthropic pressure that has caused a considerable decrease of their forest surfasse. However, they are rich in biodiversity and they provide many ecosystem services and were, therefore, classified as \"hotspots\" (forests in risk). Therefore, is essential to study the natural dynamics and the climatic response of the trees of these forests to include conservation projects and strategic measures. To achieve these objectives, the scientific literature reports that tree growth rings are the only ecological indicators with annual resolution that can be efficient and highly accurate to obtain this information. In this context, the research project has as main objective the retrospective analysis of radial growth of forest species in different vegetation communities of BAF and CMF in response to climatic changes. To achieve this goal, four key questions were elaborated: 1) Which variable explains betterthe variability of radial growth at different spatial and temporal scales? 2) What is the growth resilience to recent climate changes? 3) Is there some more vulnerable population to expected climatic changes?. A total of five sites (seven populations) of Cedrela odorata and C. fissilis in BAF from the State of São Paulo in Brazil, and five sites (10 populations) of Nothofagus macrocarpa (FMC) from the central region of Chile were sampled, using a non-destructive method. Four chapters were developed to answer these questions. Chapter I seek to analyze the resilience in radial growth to changes in regional climate variability and droughts, in temporal and spatial scale, on Atlantic forest remnant forests of biogeographic region Serra do Mar. Results show that radial growth in wet sites (winter rains exceed 240 mm) depend on the moisture conditions in dry season, while the higher population is more sensitive to the favorable summer water condition, which would be explained because this population received a lower temperature than the other Cedrela spp. populations studied. Chapter II analyzed how recent climatic variability affected the radial growth in N. macrocarpa populations. It is observed that all the populations are closely linked to the precipitations of May-November (end of autumn/end of spring) and average temperature of October-December (mid-spring/early summer). In Chapter III, we continued exploring the growth responses to climate in the FMC populations in order to find biogeographic differences. In this sense, we evaluated if this significant decrease in tree growth is differentiated between populations and age classes, and determine if the positive effect of CO2 fertilization compensates the precipitation decrease and temperature increase in the last decades in the growth of older, maturer and younger trees . Results show a significant negative trend in all classes from the year 2000, which would be associated to a decrease in precipitation in all populations while temperature was more associated with the northern and southern populations (distribution limit). We did not find a positive effect of rising CO2. Finally, chapter IV integrated the results of the two biomes comparing the projections of aboveground trees biomass under two climatic scenarios of CMIP5 project (light and severe), in order to know which populations are more vulnerable to rising temperature forecasted by year 2100, using ring width data, wood density and allometric equations. This study will provide an overview of adaptation to recent and projected climatic changes of two hotspot neotropical biomes. Although they are different in structure-biodiversity-climate are in risk. Thus, we can understand the vulnerability of threatened forests in South America to global warming that, although they are in protected areas, does not guarantee their persistence. / Os biomas classificados como Mata Atlancia Brasileira (MAB) e da Floresta Mediterrânea Chilena (FMC) têm sido afetados pela pressão antrópica que tem causado uma diminuição considerável de sua superfície florestal. No entanto são ricas em biodiversidade e providenciam muitos serviços ecossistêmicos, pelo que foram classificadas como hotspot (florestas em risco). Portanto, é fundamental estudar a dinâmica natural e a resposta climática das árvores dessas florestas para incluir em projetos de conservação. Para atingir esses objetivos, a literatura científica reporta que os anéis de crescimento das árvores são os únicos indicadores ecológicos com resolução anual que podem ser eficientes e de elevada precisão para obter essas informações. Neste contexto, o projeto de pesquisa tem como objetivo geral a analise retrospectivo de crescimento radial de espécies florestais em diferentes comunidades vegetacionais da MAB e FMC em resposta às mudanças climaticas. Para atingir esse objetivo foram elaboradas quatro perguntas-chave: 1) Que variable explica melhor a variabilidade do crescimento radial a diferentes escalas espaciais e temporais? 2) Qual é a resiliência em crescimento das árvores às mudanças climáticas recentes? 3) Há alguma população mais vulnerável respeito às mudanças climaticas esperadas?. Foram coletadas amostras de lenho, através de método não destrutivo, de cinco sitios (sete populações) de Cedrela odorata e C. fissilis na MAB no estado de São Paulo em Brasil, e cinco sitios (10 populações) de Nothofagus macrocarpa na FMC na região central do Chile, para aplicação de tecnicas dendrocronologicas. Para responder essas questões foram desenvolvidos quatro capitulos. O capitulo I busca analisar a resiliência em crescimento radial às mudanças na variabilidade climática regional e secas, em escala temporal e espacial, em florestas remanentes da região biogeográfica Serra do Mar da Mata Atlântica, usando as especies bioindicadoras Cedrela fissilis and C. odorata. Os resultados mostram que o crescimento radial dos sítios mais úmidos (chuvas no inverno superam os 240 mm) dependem das condições hidricas da estação seca, enquanto que a população mais alta é mais sensível à condição hídrica favorável do verão, qual seria explicado porque essa população recebi uma menor temperatura respeito às outras populações de cedrela estudadas. No capitulo II analisou-se como a variabilidade climática recente estaria afeitando o crescimento radial in N. macrocarpa populations. Observa-se que todas as populações estão estreitamente ligadas às precipitações de Maio-Novembro (fim de outono/fim de primaveira) e temperatura média de Outubro-Dezembro (mediados de primaveira/inicios do verão). Especificamente, há uma tendencia negativa significativa no crescimento radial apartir de 1980 que esta associada a uma variação do clima regional. No capitulo III, continuo-se explorando as respostas do crescimento radial ao clima nas populações da FMC com objetivo de encontrar diferencias biogeográficas. Neste sentido, foi avaliado se essa diminuição significativa de crescimento é diferenciada entre populações e classes de idade, e analisar se o efeito positivo da fertilização de CO2 compensa a diminuição da precipitação e aumento da temperatura nas ultimas decadas no crescimento de árvores velhos, maduros e jovens. Os resultados mostram uma tendencia negativa significativa em todas as clases apartir do ano 2000, qual estaria associada a diminuição da precipitação em todas as populações enquanto a temperatura teve mais associada às populações do sul. Não foi encontrado um efeito positivo do aumento de CO2. Finalmente, o capitulo IV integrou os resultados dos dois biomas comparando as proyeções de biomasa arborea sob dois escenarios climáticos do projeto CMIP5 (leve e severo), com objetivo de conocer quais populações são mais vulneraveis ao aumento da temperature previsto para o ano 2100, usando crescimento radial, densidade de madeira e ecuações alométricas. Os resultados mostram que a população com maior influencia urbana e a mais seca são as mais vulneráveis ao aumento exarcerbado de temperatura nas regiões de MAB and FMC, respectivamente. O presente estudo permitiu-nos apresentar uma visão da adaptação às mudanças climáticas recentes e projetadas de dois biomas hotspot. Embora sejam diferentes em estrutura-biodiversidade-clima estão em risco. Assim, podemos entender a vulnerabilidade de florestas neotropicais ao aquecimento global, embora estejam em áreas protegidas, não garante sua persistência.

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No. of bitstreams: 1 Tese-Gerlandio Suassuna Gonçalves.pdf: 1253081 bytes, checksum: bb8f078c3065d7b328b0bbf489d24eba (MD5) Previous issue date: 2015-02-10 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The determination of the critical period of weed interference is very important because it indicates the phase of the culture in which the management of weed shall be performed, furthermore, it limits the number of weeding and other management practices to the minimum, allowing the plant express its maximum yield potential at lower cost to the producer. The aim of this study was to identify the critical period of weed interference in the culture of orange ‘Pera’ tree by parameters valuated: falling immature fruits, productivity, juice yield, juice chemical characteristics, production of photosynthetic pigments and proline in leaves of orange tree, identify the weed species and their accumulation of biomass and nutrients. The experiment was installed in october 2012 and conducted until september 2014, in Rio Preto da Eva - AM. To define the treatments with and without interference of weeds in orange tree, was taken as reference the water balance in the region. The interference periods were defined considering the degree of water availability or absence in the soil: from october to january; february to may; june to september; october to may; october to January, june to september and february to september; period without weed interference (control treatment), and without producer management practices interference. The control of weed was obtained using the herbicide glyphosate (1.720 g ha-1 e.a.). The characteristics evaluated were: Falling immature fruits, productivity, juice yield, total soluble solids (SS), titratable acidity (TA), technological index (TI), chlorophyll production and carotenoids, proline content, biomass accumulation and nutrients by weeds. The treatment with weed interference in the period from october to may increase the fruit drop, reduced the number of fruits per plant and productivity, promoted an increase in soluble solids (SS), total acidity (TA) and reduced values of SS/TA ratio. The different periods of weed interference did not promote significant changes in the contents of chlorophyll a, b, total and of carotenoids in orange tree leaves, but viii promoted significant changes in the free proline content in the leaves. The weed species differ from each other in the accumulation of biomass and nutrients. The critical period of weed interference to the culture of orange ‘Pera’ was from october to may. / A determinação do período crítico de interferência de plantas infestantes é muito importante, pois seu conhecimento indica a fase da cultura em que o manejo das infestantes deve ser realizado, limita o número de capinas e de outras práticas de manejo ao mínimo necessário, possibilitando que a planta expresse o seu máximo potencial produtivo com menor custo para o produtor. O objetivo deste trabalho foi identificar o período crítico de interferência de plantas infestantes na cultura da laranja ‘Pera’ pela avaliação dos parâmetros: queda de frutos imaturos, produtividade, rendimento em suco e suas características químicas, produção de pigmentos fotossintéticos e de prolina nas folhas de laranjeira e identificar as espécies infestantes assim como a acumulação de biomassa e de nutrientes por elas. O experimento foi instalado em outubro de 2012 e conduzido até setembro de 2014, no município de Rio Preto da Eva – AM. Para definição dos tratamentos de interferência ou não de plantas infestantes em laranjeira, tomou-se como referência o balanço hídrico da região. Os períodos de interferência estabelecidos levaram em consideração o grau de disponibilidade ou não de água no solo: de outubro a janeiro; fevereiro a maio; junho a setembro; de outubro a maio; outubro a janeiro e de junho a setembro; fevereiro a setembro; sem interferência das plantas infestantes – tratamento controle; e sem interferência com práticas de manejo do produtor. O controle das plantas infestantes foi obtido com uso do herbicida glyphosate (1.720 g ha-1 e.a.). As características avaliadas foram: queda de frutos imaturos, produtividade, rendimento em suco, sólidos solúveis totais (SS), acidez titulável (AT), índice tecnológico (IT), produção de clorofila e de carotenoides, teor de prolina, acumulação de biomassa e nutrientes pelas infestantes. O tratamento com interferência das plantas infestantes no período de outubro a maio aumentou a queda de frutos prematuros, reduziu o número de frutos por planta e a produtividade, promoveu incremento dos sólidos solúveis (SS), da acidez total (AT) e reduziu vi os valores da relação SS/AT. Os diferentes períodos de interferência de plantas infestantes não promoveram alterações significativas nos teores de clorofila a, b, total e de carotenoides em folhas de laranjeira, mas promoveram mudanças significativas no conteúdo de prolina livre nas folhas. As espécies infestantes diferiram entre si na acumulação de biomassa e de nutrientes. O período crítico de interferência de plantas infestantes para a cultura da laranjeira foi de outubro a maio.

Biomes classified as Brazilian Atlantic Forest (BAF) and the Chilean Mediterranean forest (CMF) have been affected by anthropic pressure that has caused a considerable decrease of their forest surfasse. However, they are rich in biodiversity and they provide many ecosystem services and were, therefore, classified as \"hotspots\" (forests in risk). Therefore, is essential to study the natural dynamics and the climatic response of the trees of these forests to include conservation projects and strategic measures. To achieve these objectives, the scientific literature reports that tree growth rings are the only ecological indicators with annual resolution that can be efficient and highly accurate to obtain this information. In this context, the research project has as main objective the retrospective analysis of radial growth of forest species in different vegetation communities of BAF and CMF in response to climatic changes. To achieve this goal, four key questions were elaborated: 1) Which variable explains betterthe variability of radial growth at different spatial and temporal scales? 2) What is the growth resilience to recent climate changes? 3) Is there some more vulnerable population to expected climatic changes?. A total of five sites (seven populations) of Cedrela odorata and C. fissilis in BAF from the State of São Paulo in Brazil, and five sites (10 populations) of Nothofagus macrocarpa (FMC) from the central region of Chile were sampled, using a non-destructive method. Four chapters were developed to answer these questions. Chapter I seek to analyze the resilience in radial growth to changes in regional climate variability and droughts, in temporal and spatial scale, on Atlantic forest remnant forests of biogeographic region Serra do Mar. Results show that radial growth in wet sites (winter rains exceed 240 mm) depend on the moisture conditions in dry season, while the higher population is more sensitive to the favorable summer water condition, which would be explained because this population received a lower temperature than the other Cedrela spp. populations studied. Chapter II analyzed how recent climatic variability affected the radial growth in N. macrocarpa populations. It is observed that all the populations are closely linked to the precipitations of May-November (end of autumn/end of spring) and average temperature of October-December (mid-spring/early summer). In Chapter III, we continued exploring the growth responses to climate in the FMC populations in order to find biogeographic differences. In this sense, we evaluated if this significant decrease in tree growth is differentiated between populations and age classes, and determine if the positive effect of CO2 fertilization compensates the precipitation decrease and temperature increase in the last decades in the growth of older, maturer and younger trees . Results show a significant negative trend in all classes from the year 2000, which would be associated to a decrease in precipitation in all populations while temperature was more associated with the northern and southern populations (distribution limit). We did not find a positive effect of rising CO2. Finally, chapter IV integrated the results of the two biomes comparing the projections of aboveground trees biomass under two climatic scenarios of CMIP5 project (light and severe), in order to know which populations are more vulnerable to rising temperature forecasted by year 2100, using ring width data, wood density and allometric equations. This study will provide an overview of adaptation to recent and projected climatic changes of two hotspot neotropical biomes. Although they are different in structure-biodiversity-climate are in risk. Thus, we can understand the vulnerability of threatened forests in South America to global warming that, although they are in protected areas, does not guarantee their persistence. / Os biomas classificados como Mata Atlancia Brasileira (MAB) e da Floresta Mediterrânea Chilena (FMC) têm sido afetados pela pressão antrópica que tem causado uma diminuição considerável de sua superfície florestal. No entanto são ricas em biodiversidade e providenciam muitos serviços ecossistêmicos, pelo que foram classificadas como hotspot (florestas em risco). Portanto, é fundamental estudar a dinâmica natural e a resposta climática das árvores dessas florestas para incluir em projetos de conservação. Para atingir esses objetivos, a literatura científica reporta que os anéis de crescimento das árvores são os únicos indicadores ecológicos com resolução anual que podem ser eficientes e de elevada precisão para obter essas informações. Neste contexto, o projeto de pesquisa tem como objetivo geral a analise retrospectivo de crescimento radial de espécies florestais em diferentes comunidades vegetacionais da MAB e FMC em resposta às mudanças climaticas. Para atingir esse objetivo foram elaboradas quatro perguntas-chave: 1) Que variable explica melhor a variabilidade do crescimento radial a diferentes escalas espaciais e temporais? 2) Qual é a resiliência em crescimento das árvores às mudanças climáticas recentes? 3) Há alguma população mais vulnerável respeito às mudanças climaticas esperadas?. Foram coletadas amostras de lenho, através de método não destrutivo, de cinco sitios (sete populações) de Cedrela odorata e C. fissilis na MAB no estado de São Paulo em Brasil, e cinco sitios (10 populações) de Nothofagus macrocarpa na FMC na região central do Chile, para aplicação de tecnicas dendrocronologicas. Para responder essas questões foram desenvolvidos quatro capitulos. O capitulo I busca analisar a resiliência em crescimento radial às mudanças na variabilidade climática regional e secas, em escala temporal e espacial, em florestas remanentes da região biogeográfica Serra do Mar da Mata Atlântica, usando as especies bioindicadoras Cedrela fissilis and C. odorata. Os resultados mostram que o crescimento radial dos sítios mais úmidos (chuvas no inverno superam os 240 mm) dependem das condições hidricas da estação seca, enquanto que a população mais alta é mais sensível à condição hídrica favorável do verão, qual seria explicado porque essa população recebi uma menor temperatura respeito às outras populações de cedrela estudadas. No capitulo II analisou-se como a variabilidade climática recente estaria afeitando o crescimento radial in N. macrocarpa populations. Observa-se que todas as populações estão estreitamente ligadas às precipitações de Maio-Novembro (fim de outono/fim de primaveira) e temperatura média de Outubro-Dezembro (mediados de primaveira/inicios do verão). Especificamente, há uma tendencia negativa significativa no crescimento radial apartir de 1980 que esta associada a uma variação do clima regional. No capitulo III, continuo-se explorando as respostas do crescimento radial ao clima nas populações da FMC com objetivo de encontrar diferencias biogeográficas. Neste sentido, foi avaliado se essa diminuição significativa de crescimento é diferenciada entre populações e classes de idade, e analisar se o efeito positivo da fertilização de CO2 compensa a diminuição da precipitação e aumento da temperatura nas ultimas decadas no crescimento de árvores velhos, maduros e jovens. Os resultados mostram uma tendencia negativa significativa em todas as clases apartir do ano 2000, qual estaria associada a diminuição da precipitação em todas as populações enquanto a temperatura teve mais associada às populações do sul. Não foi encontrado um efeito positivo do aumento de CO2. Finalmente, o capitulo IV integrou os resultados dos dois biomas comparando as proyeções de biomasa arborea sob dois escenarios climáticos do projeto CMIP5 (leve e severo), com objetivo de conocer quais populações são mais vulneraveis ao aumento da temperature previsto para o ano 2100, usando crescimento radial, densidade de madeira e ecuações alométricas. Os resultados mostram que a população com maior influencia urbana e a mais seca são as mais vulneráveis ao aumento exarcerbado de temperatura nas regiões de MAB and FMC, respectivamente. O presente estudo permitiu-nos apresentar uma visão da adaptação às mudanças climáticas recentes e projetadas de dois biomas hotspot. Embora sejam diferentes em estrutura-biodiversidade-clima estão em risco. Assim, podemos entender a vulnerabilidade de florestas neotropicais ao aquecimento global, embora estejam em áreas protegidas, não garante sua persistência.