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Abstract(s)
Os relatos de escassez de árvores em Trás-os-Montes remontam ao início da Idade Moderna. No final do séc. XIX, na região, chegou-se a recolher esterco de bovino para produzir calor. As causas da intensa desarborização das paisagens transmontanas, e de todo o mediterrânico, não são consensuais. Com base na bibliografia agronómica regional testaram-se duas hipóteses relacionadas entre si: 1) a agricultura foi o grande motor da desarborização na Terra Fria Transmontana e, implicitamente, das montanhas mediterrânicas; 2) a floresta desapareceu porque ocultava no lenho ou no solo algo que a agricultura sempre necessitou: nutrientes. No início do artigo argumenta-se que a evolução e o desenho dos sistemas orgânicos tradicionais de agricultura foram determinados pela contínua necessidade de reconstruir os níveis de fertilidade das terras cultivadas. Os pequenos herbívoros domésticos desempenhavam um papel crucial na colheita, transporte e deposição dos nutrientes vegetais do monte para as terras de pão. Como a floresta indígena é incompatível com o pastoreio animal, o aumento da procura de alimentos redundou na conversão de floresta em pastagem. Sempre que a reposição da fertilidade da terra entrasse em rutura por falta de pasto (e de floresta para converter em pastagem), o centeio, o principal alimento regional, teria que ser estendido às terras virgens de monte. Um estudo de caso centrado na aldeia de Zedes (Carrazeda de Ansiães), no início da década de 1920, mostrou que o nutrient mining nas áreas de monte era insuficiente para fertilizar as áreas de cultivadas com centeio e que pouco espaço poderia sobrar para a floresta. O crescimento da população ocorrido a partir do final da década de 1930 causou numa expansão do cereal às terras de monte cujas consequências foram bem compreendidas pelos autores regionais.
Descriptions of tree’s scarcity in Northeastern Portugal go back to the beginnings of Modern Age. In the end of the XIX century, in the region, due to the lack of wood there was even the need to recollect cow dung to make fire. The causes of the intense deforestation in Northeastern Portugal, and in the entire Mediterranean basin, are not consensual. Based in the agronomical regional bibliography two hypotheses were tested: 1) agriculture was the main driver of the deforestation of Northeastern Portugal and, implicitly, in Mediterranean mountains; 2) forest vanished because it hided in the wood and in the soil something that agriculture always needed: plant nutrients. In the beginning of the paper we argue that the evolution and the structure of the organic traditional agricultural systems were determined by the continuous need to return plant nutrients to cultivated soils. Small domestic herbivores had a crucial role in the gathering, transport and deposition of plant nutrients from rangelands into the lands cultivated with rye. Indigenous forest is incompatible with small livestock grazing, so any increase in food demand implied the conversion of forest to grassland. If land fertility rebuilding was interrupted by the lack of grasslands (or of forest convertible to grassland), rye had to expand to virgin rangeland soils. A study case centered in Zedes village (Carrazeda de Ansiães, Portugal) in the beginnings of the 1920 decade showed that nutrient mining in rangelands was insufficient to fertilize the cultivated rye, the main traditional food, and that few space could be spared to the forest. Population growth resumed in the end of the 1930 caused an expansion of rye at expense of rangelands which consequences were well understood by contemporary regional authors.
Descriptions of tree’s scarcity in Northeastern Portugal go back to the beginnings of Modern Age. In the end of the XIX century, in the region, due to the lack of wood there was even the need to recollect cow dung to make fire. The causes of the intense deforestation in Northeastern Portugal, and in the entire Mediterranean basin, are not consensual. Based in the agronomical regional bibliography two hypotheses were tested: 1) agriculture was the main driver of the deforestation of Northeastern Portugal and, implicitly, in Mediterranean mountains; 2) forest vanished because it hided in the wood and in the soil something that agriculture always needed: plant nutrients. In the beginning of the paper we argue that the evolution and the structure of the organic traditional agricultural systems were determined by the continuous need to return plant nutrients to cultivated soils. Small domestic herbivores had a crucial role in the gathering, transport and deposition of plant nutrients from rangelands into the lands cultivated with rye. Indigenous forest is incompatible with small livestock grazing, so any increase in food demand implied the conversion of forest to grassland. If land fertility rebuilding was interrupted by the lack of grasslands (or of forest convertible to grassland), rye had to expand to virgin rangeland soils. A study case centered in Zedes village (Carrazeda de Ansiães, Portugal) in the beginnings of the 1920 decade showed that nutrient mining in rangelands was insufficient to fertilize the cultivated rye, the main traditional food, and that few space could be spared to the forest. Population growth resumed in the end of the 1930 caused an expansion of rye at expense of rangelands which consequences were well understood by contemporary regional authors.
Description
Keywords
Paisagem Nutrição História do território Floresta
Citation
Aguiar, Carlos; Azevedo, João (2011). A floresta e a restituição da fertilidade do solo nos sistemas de agricultura orgânicos tradicionais do NE de Portugal no início do séc. XX. In Tereso JP, Honrado JP, Pinto AT, Rego FC (Eds.) Florestas do Norte de Portugal: História, Ecologia e Desafios de Gestão. InBio - Rede de Investigação em Biodiversidade e Biologia Evolutiva. Porto: InBio. p 100-117. ISBN 978-989-97418-1-2.