http://hdl.handle.net/10316/15924 Mon, 24 Feb 2020 13:02:36 GMT 2020-02-24T13:02:36Z http://hdl.handle.net/10316/44374 Title: Cambial activity and wood formation of Maritime pine in a drought-prone environment: the effect of growth rate, size and climate Authors: Vieira, Joana Abstract: The formation of tree rings is a slow and complex process. The year-to-year climatic variability and the constant interaction between the internal and external factors controlling cambial activity create the conditions that make each tree ring unique. In order to capture the dynamics of cambial activity and wood formation during the growing season, it is necessary to monitor wood development in narrower time intervals (from minutes to weeks). Most of the studies performed on cambial activity and wood formation were held in cold environments, however, in other environments, such as drought-prone areas, it still remains poorly understood. In order to understand cambial activity and wood formation in a drought-prone environment, timings and dynamics of cambial activity were monitored in maritime pine (Pinus pinaster Ait.) growing in the Mediterranean region for two years (2010 and 2011). Anatomical observations of the cambial zone and differentiating xylem were made and stem radial increment monitored using manual and automatic dendrometers. The studies described in this thesis were carried out in Perimetro Florestal Dunas de Cantanhede, a managed plantation of maritime pine located in the west coast of Portugal. The cambial activity and wood formation of maritime pine trees with the same age and size but different growth rates in the period 2009-1994 (classified as fast and slow trees), were monitored throughout 2010, to determine whether the observed differences in tree-ring width were triggered by timings of cambial activity or by rates of cell production. Anatomical observations of the cambium and developing xylem determined that the timing of cambial activity was similar in both growth rate classes. However, fast-growing trees presented higher rates of cell production than slow-growing trees. The band dendrometer readings revealed a bimodal pattern of stem radial increment, with two peaks of increment, one more pronounced in spring and another in autumn. Although the bimodal pattern is typical of trees growing in the Mediterranean region, the combined analysis of anatomical observations and band dendrometers showed that the second period of radial increment corresponded mostly to the re-hydration of the stem, since no resumption of cambial activity was observed in autumn. In order to determine if differences in stem diameter were due to different rates of cell production or xylogenesis timings, the cambial activity of even-aged trees belonging to two diameter classes was monitored throughout 2011. The timings of cambial onset and differentiation were the same in both diameter classes. However, enlargement and cell wall deposition lasted longer in large trees. Besides the different durations, large trees also showed a higher rate of cell production. Thus, revealing that the differences in diameter observed between the trees were due to the rates of cell production. In both diameter classes, the cambium was active from March to July, and quiescent from August to November, suggesting that in the Mediterranean region trees are under a double climatic control: low temperatures and reduced photoperiod in the winter and high temperatures associated with low water availability in the summer. Summer quiescence was broken in late October, when precipitation re-hydrated the stem. In November, cambial divisions were observed, indicating that maritime pine has the ability to form new xylem cells after the summer drought. The influence of climate on the cambial activity and wood formation of maritime pine was studied over two dry years (2010 and 2011). It was found that cambial onset started earlier in response to a warmer late-winter and stopped earlier in response to a drier spring and summer, confirming that Mediterranean conifers are under a double climatic control. Low water availability during spring and summer limited cell production, which affected tree-ring width. Drier conditions also triggered an earlier start of latewood formation, leading to the development of fewer tracheids with smaller lumen area. It was also observed that the duration of xylogenesis was not dependent on cambial onset. In fact, an earlier onset of xylogenesis did not trigger a longer duration of cambial activity. To ascertain the influence of water availability on the stem radial increment of maritime pine, hourly variations of stem radial increment and tree water deficit were monitored throughout 2010 using automatic dendrometers. The seasonal cycle was divided in five periods of distinct physiological activity: winter dormancy, spring growth, pre-summer contraction, summer quiescence and autumn re-hydration. The stem cycle approach was then used to divide the daily cycles in contraction, recovery and increment phases. Continuous positive radial increment started in spring and reached its maximum by the end of June, time at which a shrinking period was observed. The stem contraction observed in June was due to the inability of trees to recover the water lost by transpiration, contracting from one cycle to the next. In autumn, a period of re-hydration and rapid expansion was observed after precipitation. Daily variations in stem radius of maritime pine were mainly determined by the course of transpiration and thus, highly dependent on temperature and water availability. Overall, the results obtained in this dissertation provided a detailed insight on the dynamics of maritime pine cambial activity in a drought-prone environment, the Mediterranean region. It was observed that cell production rate was the main responsible for the differences in tree-ring width and ultimately in stem diameter. Within an even-aged and managed forest, different individuals can present different cellular production rates (fast and slow trees) that in time will be translated in different stem diameters (larger and smaller trees). Growth onset was not influenced by tree size, but a longer duration of wood formation was observed in fast-growing and larger trees. In both years (2010 and 2011), the radial increment of all studied trees presented a clear bimodal pattern, with two increment peaks, as observed in other Mediterranean species. The first and more pronounced peak occurred in spring and a second less pronounced peak in autumn. The second growth peak corresponded mainly to a re-hydration of the stem after the summer drought, since the anatomy study did not reveal the formation or differentiation of new xylem cells. Climate played an important role in maritime pine cambial activity and wood formation, low temperatures and reduced photoperiod in winter and high temperatures associated with low water availability in the summer limited tree growth by imposing a dormant period. Fri, 13 Dec 2013 00:00:00 GMT http://hdl.handle.net/10316/44374 2013-12-13T00:00:00Z http://hdl.handle.net/10316/27321 Title: Modelo de avaliação de sustentabilidade integrado e global para ecossistemas florestais: Bioenergia, produtos derivados de madeira e co-produtos Authors: Nunes, João Miguel dos Santos Almeida Abstract: Compete aos silvicultores e gestores de recursos naturais assegurar o equilíbrio entre objetivos conflituantes no desenvolvimento de planos pelo uso do território. Os conflitos podem englobar objetivos económicos, ambientais, sociais, culturais, técnicos e muitos outros. Selecionar a melhor combinação de processos, em cadeias de valor complexas e compostas por numerosos objetivos, é difícil e desafiador. Os modelos Multicritério de Decisão fornecem um meio sistemático para comparar vantagens e desvantagens, e selecionar alternativas que melhor satisfazem os objetivos do decisor. A conciliação deste com a abordagem da metodologia de Avaliação de Ciclo de Vida e os critérios e indicadores de sustentabilidade são uma mais-valia para o desenvolvimento de um modelo de avaliação, quer pelo contexto de ciclo de vida completo e sistema, como pela compacidade comparativa que confere. É importante ainda ter em consideração os princípios florestais e os princípios da abordagem ecossistémica. O principal objetivo do presente trabalho consiste no desenvolvimento de um modelo de apoio à decisão aplicado à avaliação de sustentabilidade integrado para os ecossistemas florestais com potencial de aplicação à escala global. Este modelo consiste na avaliação e na comparação multicritério das alternativas de gestão e exploração florestal ao nível das principais cadeias de valor, e de acordo com os princípios de base definidos na conferência da Nações Unidas em 1972 para o conceito Sustentabilidade. Apresenta um particular interesse devido aos problemas de desequilíbrio das atividades económicas, de competição pelos recursos e de definição de cascatas de valor. Realizou-se primeiro uma análise sobre a realidade da atividade económica da floresta portuguesa, concluindo-se que os povoamentos de pinheiro bravo diminuíram significativamente nos últimos anos a uma taxa de 17,5 mil/ha/ano e os eucaliptos cresceram a uma taxa de 6,3 mil ha/ano. Caso não exista nenhuma alteração, os povoamentos de eucaliptos serão o ecossistema predominante da floresta portuguesa nas próximas décadas: em 2029 existirão 529,0 mil ha no terceiro corte e que apresentarão menor interesse económico. Além disso, verificou-se que a introdução dos “pellets” em Portugal ocorreu de forma muito rápida. Portugal é o país do mundo com maior capacidade instalada por cada 1 milhão de hectare de floresta, com 305.300,0 ton/1 milhão ha floresta e a Europa 19.500,0 ton/1 milhão ha floresta. O balanço comercial em Portugal da atividade relacionada com a floresta e madeira é de aproximadamente 1.503,8 milhões €/ano. Portugal aparece, em 2012, na 5ª posição do TOP 25 dos países com maior balanço económico entre exportações e importações, com um balanço de 185,5 US$/per capita e a 2ª posição em termos US$/ha de floresta. Contudo, os incêndios florestais apresentam uma perda económica média anual 961,3 - 1.007,5 milhões euros, com um impacto de 63,9% a 70,0% na balança comercial. Tendo em consideração os problemas das externalidades negativas dos incêndios florestais, Portugal passaria de 2.º lugar no ranking de produtividade US$/ha floresta para 7.º. No presente estudo desenvolveu-se uma ferramenta de apoio à decisão e de avaliação para ecossistemas florestais, denominada por “Forest GTS: Forest Global True Sustainability”. Tendo-se verificado que a definição de critérios mínimos é a solução para alcançar uma ferramenta de apoio à decisão com potencial de aplicação à escala global, conseguiu-se, através do cruzamento de 15 processos e esquemas identificados como os mais importantes a nível internacional, definir um conjunto de 15 critérios ambientais, 7 económicos e 14 sociais, os quais originaram 37 indicadores ambientais, 14 económicos e 22 sociais. A Forest GTS é assim uma ferramenta poderosa de avaliação de sustentabilidade para ecossistemas florestais e que poderá funcionar como um “umbrela” aos sistemas de certificação florestal, permitindo ainda a avaliação entre sistemas energéticos e de transformação de madeira. Apresenta também potencial de aplicação no suporte à decisão de políticos, entidades governamentais, empresas e outros agentes a avaliar o grau de sustentabilidade de uma ou diversas cadeias de valor florestais. A globalização da Forest GTS a um contexto europeu permitiria a definição da cascata de valor da floresta europeia, o dimensionamento de mercado de exploração dos recursos e a definição de prioridades de industrialização ou re-industrialização. A Forest GTS foi desenvolvida com base na metodologias “Analytic Hierarchy Process, AHP” e “MultiAttribute Utility Theory, MAUT” com a integração da Avaliação de Ciclo de Vida. São modelados cenários que têm como objetivo descrever a evolução, posição e prever o resultado de alternativas possíveis de exploração e suas consequências para as características da floresta. Esta metodologia é aplicada à gestão integrada da floresta da região centro de Portugal tendo como unidade funcional 1 ha representativo da predominância ecológica e económica da região (povoamentos de matos e incultos, pinheiro bravo e eucaliptos). Foi possível obter informação para 92,1% dos indicadores ambientais, 92,8% dos económicos e 68,2% dos sociais da Forest GTS, para as principais cadeias de valor da região centro. Apesar dos anos de inventário realizado no presente estudo verificou-se que existe falta de informação importante para garantir o cálculo de todos os indicadores. Avaliaram-se 18 cadeias de valor existentes e mais 3 cenários novos de exploração dos ecossistemas florestais da região centro de Portugal. Os novos cenários são modelados com base na informação obtida em dois projetos de investigação na área das biorrefinarias – o BioREFINA-Ter – e na área dos aglomerados técnicos – o Woodcare. O presente estudo conclui que 61,0% das principais cadeias de exploração económica da floresta da região centro são sustentáveis. O valor médio do índice de avaliação de sustentabilidade para o ano 2013, IGTS,2013, é de 51,0. As cadeias de valor energéticas de exploração de rolaria de pinheiro bravo e todas as cadeias de valor com origem em povoamentos de eucaliptos obtiveram um desempenho insustentável, ou seja, apresentaram um IGTS,2013 inferior a 50,0. Caso não haja nenhuma alteração face ao atual, os povoamentos de eucaliptos serão os principais e dominantes da região centro, perspetivando-se, com base nos resultados obtidos pelo modelo da Forest GTS que irão existir problemas de sustentabilidade nos ecossistemas florestais da região centro de Portugal. Identificaram-se também oportunidades de melhoria de exploração dos ecossistemas da região centro de Portugal, através da implementação de novos cenários de exploração económica dos ecossistemas de matos e incultos (que apresentam implicações significativas ao nível dos grandes incêndios florestais) e de povoamentos de pinheiro bravo. Exemplo desses novos cenários seria uma aposta pelas biorrefinarias ao nível dos Matos e Incultos e resíduos florestais e no desenvolvimento de mercados de aplicação técnica para aglomerados de madeira com aplicação no setor da qualidade do ar interior de edifícios.; Forest owners and natural resource managers have the responsibility to ensure an equilibrium between conflicting objectives of the development of land use strategies. Conflicts may include economic, environmental, social, cultural, technical, and many others objectives. It is difficult and challenging to select the best combination of processes in complex value chains aiming at numerous targets. Models of Multi-criteria Decision provide a systematic mean to compare advantages and disadvantages, and to select alternatives that best meet the objectives of the decision maker. This model, together with sustainability criteria and indicators and a Life Cycle Assessment approach, consists of a valuable asset for the development of an evaluation model, whether by the perspective of a complete life cycle and system, or by the comparative compactness it provides. It is also important to take into account the forestry and the ecosystem approach principles. The main goal of the present work is to develop a decision support model applied to an integrated sustainability assessment for forest ecosystems, with potential for worldwide application. This model is based on a multi-criteria evaluation and comparison of forest management and exploitation alternatives in the main value chains, and according to the basic principles set out in the United Nations conference in 1972, for the Sustainability concept. This subject is particularly interesting due to problems arising from an imbalance in economic activities, from resource competition and from establishment of value’s cascade. An analysis on the actual economic activity of the Portuguese forest was primarily performed, leading to the conclusion that maritime pine stands have decreased significantly over the past years at a rate of 17,500.0/ha/year as opposed to eucalyptus which have grown at a rate of 6,300.0 ha/year. The stands of eucalyptus trees will be the predominant ecosystem of the Portuguese forest in the coming decades, if nothing is changed compared to the present: in 2029, there will be 529,000.0 ha in the third cut, which will present lower economic interest. Furthermore, the introduction of pellets in Portugal occurred at a fast rate. Portugal has the largest installed capacity in the world per 1 million hectare of forest, with 305,300.0 ton/1 million ha forest, as opposed to Europe that merely reaches 19,500.0 ton/1 million ha forest. The trade balance in Portugal related to forest and timber activity is 1,503.8 million €/year. In 2012, Portugal was in the 5th position of the TOP 25 countries with the greatest economic balance between exports and imports, with a balance of 185.50 US$ per capita, and in the 2nd position in terms of US$/ha of forest. However, forest fires have an average annual economic loss of 961.3 to 1,007.5 million euro, and an impact of 63.9% to 70.0% in the trade balance. Considering the problems in the negative externalities of forest fires, Portugal would stand at the 7th place of the US productivity/ha forest ranking as opposed to the 2nd place originally occupied. In the present study, a supporting tool for decision making and evaluation of forest ecosystems was developed, denominated "Forest GTS: Global Forest True Sustainability". In order to achieve a supporting tool with potential for global implementation, a minimum criteria definition must be met. A set of 15 environmental, 7 economic and 14 social parameters were defined, through the conjunction of 15 different processes and schemes identified as the most important at an international level, therefore allowing the generation of 37 environmental, 14 economic and 22 social indicators. Forest GTS is thereby a powerful tool of sustainability assessment for forest ecosystems, which may function as an "umbrella" to forest certification systems, and yet allowing the assessment of energy systems and wood processing. It also presents a potential for application in supporting decisions of politicians, governmental entities, companies and other stakeholders to assess the sustainability degree of one or several forestry value chains. The globalization of Forest GTS at a European level would allow the definition of a cascade of value for the European forest, the scaling of resource exploitation market and the establishment of industrialization or re-industrialization priorities. Forest GTS was developed on the basis of “Analytic Hierarchy Process, AHP” and “Multi-Attribute Utility Theory, MAUT” methodologies in conjunction with Life Cycle Assessment. Scenarios can be modeled in order to describe the evolution, position and to predict the outcome of possible alternatives for the exploration and its consequences for the forest characteristics. This methodology is applied to the integrated management of the forest of the central region of Portugal, having as the functional unit 1ha of forest, that represents this region in terms of ecological and economic predominance (stands of woods and heath land, maritime pine and eucalyptus).It was possible to obtain information on 92.1% of the environmental indicators, 92.8% of the economic indicators and 68.2% of the social indicators from Forest GTS, for the most important value chains in the central region. Despite the years of inventory used in this study, it was found that there is a lack of relevant information to ensure the calculation of all indicators. Eighteen existing value chains and 3 more new scenarios of exploitation of the forest ecosystems of the Portuguese central region were evaluated. The new scenarios were modeled based on the information obtained in two research projects in the areas of biorefineries– the BioREFINA-Ter– and technical wood products– the Woodcare. It was concluded from the present study that 61.0% of the main chains of economic exploitation of the forest in the central region of Portugal are sustainable. The average index value of sustainability assessment for the year of 2013, IGTS,2013, was 51.0.The energy value chains of exploitation of maritime pine round wood and all the value chains originated from stands of Eucalyptus proved to have an unsustainable performance, i.e., presented an IGTS,2013 of less than 50.0. If no change occurs concerning the actual scenario, the stands of eucalyptus will be the main and predominant stands in the center region. Based on the results obtained using the Forest GTS model, it is predicted that the sustainability in forest ecosystems in the Portuguese central region will be therefore a problematic issue. Several opportunities to improve the exploitation of the ecosystems in the central region of Portugal were also identified by the implementation of new scenarios of economic exploitation of woods and heathland ecosystems(that have significant implications for any large wildfires) and stands of maritime pine. New scenarios could be achieved by strongly focusing on biorefineries based on woods, heathland and forest residues and by promoting the development of markets for technical application of wood based products applied in the sector of air quality inside buildings. Description: Tese de doutoramento em Biociências, no ramo de Ecologia, apresentada ao Departamento de Ciências da Vida da Faculdade de Ciências e Tecnologia da Universidade de Coimbra Wed, 17 Jun 2015 00:00:00 GMT http://hdl.handle.net/10316/27321 2015-06-17T00:00:00Z