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Impacto da vegetação herbácea na regeneração artificial de sobreiro (Quercus suber L.) na Companhia das Lezírias
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De ano para ano tem havido um preocupante decréscimo da área de montado de sobreiro em Portugal. Este decréscimo deve-se por um lado ao aumento da mortalidade das árvores, mas também a uma falta de sucesso da regeneração. O sucesso de regeneração é particularmente baixo nos primeiros anos de vida das plântulas principalmente devido ao stresse hídrico de verão, que pode ser agravado pela competição pela água. Assim, o objetivo desta dissertação foi compreender o efeito da remoção da vegetação herbácea, através da aplicação de uma tela anti infestantes, na sobrevivência e funcionamento de plântulas de sobreiro, durante os seus primeiros 9 meses de vida. Pretende-se, assim, compreender de que forma a remoção da vegetação herbácea poderá contribuir para um maior sucesso na regeneração do montado de sobreiro.
O estudo foi realizado num montado de sobreiro, localizado na Companhia das Lezírias, na região do Ribatejo em Portugal. Utilizaram-se bolotas recolhidas na Companhia das Lezírias que foram posteriormente conservadas. Estas bolotas foram semeadas em 5 blocos diferentes, no interior de protetores, e a sua sobrevivência e crescimento monitorizados durante 9 meses no campo. Foi ainda realizada uma parte de trabalho laboratorial, com o objetivo estudar a reação das plantas sujeitas ao tratamento de remoção da vegetação herbácea às condições de stresse (hídrico, radiação e temperatura) durante o período do verão.
Os principais resultados mostraram, ao contrário do esperado, que a remoção da vegetação herbácea contribuiu para uma menor sobrevivência das plantas de sobreiro em comparação com o tratamento controlo. No entanto, verificou-se existir uma relação positiva entre a altura da planta, antes do período de stresse hídrico, e a sobrevivência das plantas, avaliada depois do verão. As condições microclimáticas (bloco), o tipo de solo e as reservas da bolota também foram determinantes para a sobrevivência das plântulas. Assim, a sobrevivência foi superior para plântulas originadas a partir de bolotas com maior quantidade de reservas e quando apresentam um maior desenvolvimento antes do período de maior seca. Estes resultados poderão contribuir para melhorar as técnicas de restauro do montado de sobro e assim aumentar as possibilidades de regeneração de sobreiros no montado
From year to year there has been a worrying decrease in the area of cork oak forests in Portugal. This decrease is due on the one hand to an increase in tree mortality, but also to a lack of success in regeneration. Regeneration success is particularly low in the first years of seedling life mainly due to summer water stress, which can be aggravated by competition for water. Thus, the objective of this dissertation was to understand the effect of herbaceous vegetation removal, through the application of an anti-weed screen, on the survival and functioning of cork oak seedlings during their first 9 months of life. The aim is to understand how the removal of herbaceous vegetation can contribute to greater success in the regeneration of cork oak forests. The study was carried out in a cork oak forest, located in Companhia das Lezírias, in the Ribatejo region in Portugal. Acorns collected at Companhia das Lezírias that were later preserved were used. These acorns were sown in 5 different blocks, inside protectors, and their survival and growth were monitored during 9 months in the field. Part of the laboratory work was also carried out, to study the reaction of the plants subjected to the herbaceous vegetation removal treatment to stress conditions (water, radiation, and temperature) during the summer period. The main results showed, contrary to expectations, that the removal of herbaceous vegetation contributed to a lower survival of cork oak plants compared to the control treatment. However, a positive relationship was found to exist between plant height before the water stress period and plant survival as assessed after the summer. Microclimatic conditions (block), soil type, and acorn reserves were also determinants of seedling survival. Thus, survival was higher for seedlings that originated from acorns with a greater number of reserves and when they show greater development before the period of greatest drought. These results may contribute to improve the restoration techniques of the cork oak forest and thus increase the possibilities of cork oak regeneration in the montado.
From year to year there has been a worrying decrease in the area of cork oak forests in Portugal. This decrease is due on the one hand to an increase in tree mortality, but also to a lack of success in regeneration. Regeneration success is particularly low in the first years of seedling life mainly due to summer water stress, which can be aggravated by competition for water. Thus, the objective of this dissertation was to understand the effect of herbaceous vegetation removal, through the application of an anti-weed screen, on the survival and functioning of cork oak seedlings during their first 9 months of life. The aim is to understand how the removal of herbaceous vegetation can contribute to greater success in the regeneration of cork oak forests. The study was carried out in a cork oak forest, located in Companhia das Lezírias, in the Ribatejo region in Portugal. Acorns collected at Companhia das Lezírias that were later preserved were used. These acorns were sown in 5 different blocks, inside protectors, and their survival and growth were monitored during 9 months in the field. Part of the laboratory work was also carried out, to study the reaction of the plants subjected to the herbaceous vegetation removal treatment to stress conditions (water, radiation, and temperature) during the summer period. The main results showed, contrary to expectations, that the removal of herbaceous vegetation contributed to a lower survival of cork oak plants compared to the control treatment. However, a positive relationship was found to exist between plant height before the water stress period and plant survival as assessed after the summer. Microclimatic conditions (block), soil type, and acorn reserves were also determinants of seedling survival. Thus, survival was higher for seedlings that originated from acorns with a greater number of reserves and when they show greater development before the period of greatest drought. These results may contribute to improve the restoration techniques of the cork oak forest and thus increase the possibilities of cork oak regeneration in the montado.
Descrição
Mestrado em Engenharia Agronómica / Instituto Superior de Agronomia. Universidade de Lisboa
Palavras-chave
stresse hídrico e térmico montado alterações climáticas fisiologia mulching hydric and thermal stress montado climate change physiology mulching
Contexto Educativo
Citação
Matos, L.T. - Impacto da vegetação herbácea na regeneração artificial de sobreiro (Quercus suber L.) na Companhia das Lezírias. Lisboa: ISA, 2022, 96 p.