Áreas Agrícolas Sujeitas À Desertificação No Rn E Medidas Mitigadoras: O Caso Dos Assentamentos Milagres E Terra Da Esperança

Sampaio, Pedro Ramualyson Fernandes; Júnior, João Correia Saraiva; Portela, Jeane Cruz; Silva, Jucirema Ferreira da

doi:10.15628/holos.2020.5902

Cited by 3 publications

(2 citation statements)

References 2 publications

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“…Com o crescimento da pecuária na região amazônica maranhense, foi necessário abrir áreas florestadas para a criação de pastos (Silva et al, 2021). Entretanto, estas mudanças têm sido responsáveis por problemas significantes, como a desertificação e, consequentemente, a preda da biodiversidade (Sousa et al, 2012;Sampaio et al, 2020).…”

Section: Alteração Da Paisagem Da Bacia Hidrográfica Do Rio Turiaçuunclassified

Avaliação das Mudanças no Uso da Terra da Bacia Hidrográfica do Rio Turiaçu na região amazônica maranhense

Almeida

Bezerra

Santos

et al. 2022

Rev. Bras. Geog. Fis.

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O aumento da demanda de matéria-prima para saciar a necessidade de consumo tem ocasionado modificações na paisagem, como a transformação de áreas vegetadas em pastos e terras cultiváveis. Estas alterações afetam diretamente na ciclagem de nutrientes, na disponibilidade de água, a estrutura do solo e o clima, pois a cobertura vegetal é responsável pela estabilidade da bacia. Este estudo tem como objetivo mapear as classes de uso e ocupação da terra, a fim de verificar e quantificar as mudanças estruturais da paisagem ocorridas entre os anos 1985 e 2019, na Bacia Hidrográfica do Rio Turiaçu. Pois esta região, além de possuir uma alta complexidade ambiental, apresenta escassez de informações. Por isso, surge a necessidade de buscas por metodologias que auxiliem no estudo de análise de paisagem para a compreensão de determinadas relações ecológicas. Diante disso, a partir dos dados do MapBiomas foi possível elaborar o mapa da evolução do uso e ocupação da terra e analisar as métricas de paisagem. Com o mapa de uso e ocupação da terra caracterizou-se, quantitativamente, a área das classes presentes na bacia. No período estudado (1985 e 2019), houve mudanças significativas, como a redução da área de florestas e o surgimento de novas classes. As métricas de paisagem foram obtidas por meio da extensão Patch Analyst, mostrou a evolução da estrutura dos fragmentos durante os anos 1985 e 2019. Os resultados obtidos nesta pesquisa permitem concluir que a bacia sofre graves pressões antrópicas ocasionadas, principalmente, pela transformação de florestas em área de pastagem.Palavras-chave: Paisagem, Fragmentação Florestal, Unidade de Conservação Assessment of land use changes in the Turiaçu River Basin in the Amazon region of MaranhãoA B S T R A C TThe increased demand for raw material to satisfy the need for consumption has caused changes in the landscape, such as the transformation of vegetated areas into pastures and arable land. These changes directly affect nutrient cycling, water availability, soil structure and climate, as vegetation cover is responsible for the stability of the basin. This study aims to map the land use and occupation classes, in order to verify and quantify the structural changes in the landscape that occurred between 1985 and 2019, in the Turiaçu River Basin. Because this region, in addition to having a high environmental complexity, has a lack of information. Therefore, there is a need to search for methodologies that help in the study of landscape analysis to understand certain ecological relationships. Therefore, based on the data from MapBiomas, it was possible to draw up a map of the evolution of land use and occupation and analyze the landscape metrics. The land use and occupation map was used to quantitatively characterize the area of the classes present in the basin. In the period studied (1985 and 2019), there were significant changes, such as the reduction in the area of forests and the emergence of new classes. The landscape metrics were obtained through the Patch Analyst extension, showing the evolution of the fragments structure during the years 1985 and 2019. The results obtained in this research allow us to conclude that the basin suffers severe anthropogenic pressure caused, mainly, by the transformation of forests into pasture areas.Keywords: Landscape, Forest Fragmentation, Conservation Unit.

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Section: Alteração Da Paisagem Da Bacia Hidrográfica Do Rio Turiaçuunclassified

Avaliação das Mudanças no Uso da Terra da Bacia Hidrográfica do Rio Turiaçu na região amazônica maranhense

Almeida

Bezerra

Santos

et al. 2022

Rev. Bras. Geog. Fis.

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“…Aside from native people, the region has been occupied since the Portuguese colonization in the 16th century, and the ensuing intense agricultural activity has been responsible for a large-scale degradation of the Caatinga biome, the typical vegetation of NEB's semi-arid areas. This land mismanagement and the increasing frequency of regional droughts has put some of these areas at great risk of desertification (Marengo and Bernasconi, 2015;Sampaio et al, 2020). Advancing our knowledge about NEB's climate and recurrence of extreme events in a long-term context is therefore of great importance to better anticipate the impacts of these intense and abrupt drought events.…”

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confidence: 99%

Spatiotemporal ITCZ dynamics during the last three millennia in Northeastern Brazil and related impacts in modern human history

Utida

Cruz

Vuille

et al. 2023

Preprint

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Abstract. Changes in tropical precipitation over the past millennia have usually been associated with latitudinal displacements of the Intertropical Convergence Zone (ITCZ). Recent studies provide new evidence that contraction and expansion of the tropical rainbelt may also have contributed to ITCZ variability on centennial time scales. Over tropical South America few records point to a similar interpretation, which prevents a clear diagnosis of ITCZ changes in the region. In order to improve our understanding of the equatorial rainbelt variability, our study presents a reconstruction of precipitation for the last 3200 years from the Northeast Brazil (NEB) region, an area solely influenced by ITCZ precipitation. We analyze oxygen isotopes in speleothems that serve as a faithful proxy for the past location of the southern margin of the ITCZ. Our results, in comparison with other ITCZ proxies, indicate that the range of seasonal migration, contraction and expansion of the ITCZ was not symmetrical around the equator. A new NEB ITCZ pattern emerged based on the comparison between two distinct proxies that characterize the ITCZ behavior during the last 2500 years, with an ITCZ zonal pattern between NEB and the eastern Amazon. In NEB, the period related to the Medieval Climate Anomaly (MCA) was characterized by an abrupt transition from wet to dry conditions. These drier conditions persisted until the onset of the period corresponding to the Little Ice Age (LIA), representing the longest dry period over the last 3200 years in NEB. The ITCZ was apparently forced by teleconnections between Atlantic Multidecadal Variability and Pacific Decadal Variability that controlled the position, intensity and width of Walker cell over South America changing the ITCZ zonally, and sea surface temperature changes in both the Pacific and Atlantic, stretching/weaking the ITCZ-related rainfall meridionally over NEB. Wetter conditions started around 1500 CE in NEB. During the last 500 years, our speleothems document the occurrence of some of the strongest drought events for the last millennia, which drastically affected population and environment of NEB during the Portuguese colonial period. The historical droughts were able to affect the karst system, and led to significant impacts over the entire NEB region.

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Spatiotemporal Intertropical Convergence Zone dynamics during the last 3 millennia in northeastern Brazil and related impacts in modern human history

Utida,

Cruz,

Vuille

et al. 2023

Clim. Past

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Abstract. Changes in tropical precipitation over the past millennia have usually been associated with latitudinal displacements of the Intertropical Convergence Zone (ITCZ). Recent studies provide new evidence that contraction and expansion of the tropical rain belt may also have contributed to ITCZ variability on centennial timescales. Over tropical South America few records point to a similar interpretation, which prevents a clear diagnosis of ITCZ changes in the region. In order to improve our understanding of equatorial rain belt variability, our study presents a reconstruction of precipitation for the last 3200 years from the northeastern Brazil (NEB) region, an area solely influenced by ITCZ precipitation. We analyze oxygen isotopes in speleothems that serve as a faithful proxy for the past location of the southern margin of the ITCZ. Our results, in comparison with other ITCZ proxies, indicate that the range of seasonal migration, contraction, and expansion of the ITCZ was not symmetrical around the Equator on secular and multidecadal timescales. A new NEB ITCZ pattern emerges based on the comparison between two distinct proxies that characterize the ITCZ behavior during the last 2500 years, with an ITCZ zonal pattern between NEB and the eastern Amazon. In NEB, the period related to the Medieval Climate Anomaly (MCA – 950 to 1250 CE) was characterized by an abrupt transition from wet to dry conditions. These drier conditions persisted until the onset of the period corresponding to the Little Ice Age (LIA) in 1560 CE, representing the longest dry period over the last 3200 years in NEB. The ITCZ was apparently forced by teleconnections between Atlantic and Pacific that controlled the position, intensity, and extent of the Walker cell over South America, changing the zonal ITCZ characteristics, while sea surface temperature changes in both the Pacific and Atlantic stretched or weakened the ITCZ-related rainfall meridionally over NEB. Wetter conditions started around 1500 CE in NEB. During the last 500 years, our speleothems document the occurrence of some of the strongest drought events over the last centuries, which drastically affected population and environment of NEB during the Portuguese colonial period. The historical droughts were able to affect the karst system and led to significant impacts over the entire NEB region.

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Áreas Agrícolas Sujeitas À Desertificação No Rn E Medidas Mitigadoras: O Caso Dos Assentamentos Milagres E Terra Da Esperança

Cited by 3 publications

References 2 publications

Avaliação das Mudanças no Uso da Terra da Bacia Hidrográfica do Rio Turiaçu na região amazônica maranhense

Avaliação das Mudanças no Uso da Terra da Bacia Hidrográfica do Rio Turiaçu na região amazônica maranhense

Spatiotemporal ITCZ dynamics during the last three millennia in Northeastern Brazil and related impacts in modern human history

Spatiotemporal Intertropical Convergence Zone dynamics during the last 3 millennia in northeastern Brazil and related impacts in modern human history

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