O domínio ecogeográfico da caatinga ocupa uma área de cerca de 750.000 Km² e engloba partes dos territórios pertencentes aos estados do Maranhão, Piauí, Ceará, Rio Grande do Norte, Pernambuco, Paraíba, Alagoas, Sergipe, Bahia e parte de Minas Gerais. Sua área corresponde a 54% da Região Nordeste e a 11% do território brasileiro e constitui o chamado Polígono das Secas. A utilização da caatinga como pastagem extensiva vem causando degradações fortes e por vezes irreversíveis nesse ecossistema. Já são encontradas extensas áreas cuja vegetação já se encontra muito empobrecida, tendo perdido a diversificação florística que lhe é peculiar. Porém, quase sempre a regeneração não pode acontecer por causa da pressão humana intensa e constante. Esta, uma vez cessada, permitiria, a médio ou a longo prazo, que a vegetação se reconstituísse. Para que isso fosse possível seria preciso levar em conta os fatores ecogeográficos tais como: localização, tipos de solo, rochas-mãe, índices pluviométricos e duração da estação seca. Do que foi exposto sucintamente, pode-se concluir que as atividades antrópicas, em especial a pecuária extensiva, contribuíram para alterações estruturais da caatinga e que estas se refletem em seu polimorfismo, mas não são os únicos fatores. Contudo esse foi o propósito desse trabalho de apresentar uma visão ecogeográfica da caatinga submetida à atividade humana, especial a pecuária, e as conseqüências impactantes para a cobertura vegetal no semi-árido brasileiro.
BackgroundStudies on plant communities in the Amazon have reported that different hydro-edaphic conditions can affect the richness and the species composition of different ecosystems. However, this aspect is poorly known in the different savanna habitats. Understanding how populations and plant communities are distributed in these open vegetation areas is important to improve the knowledge about which environmental variables influence the occurrence and diversity of plants in this type of regional ecosystem. Thus, this study investigated the richness and composition of plant species in two savanna areas of the northern Brazilian Amazonia, using the coverage (%) of the different life forms observed under different hydro-edaphic conditions as a structural reference.New informationWe report 128 plant species classified in 34 botanical families distributed in three savanna habitats with different levels of hydro-edaphic restrictions. In this study, the habitats are conceptually presented and they integrate environmental information (edaphic factors and drainage type), which determines differences between floristic composition, species richness and coverage (%) of plant life forms.
Cabbage cultivation with organic inputs in agroforestry systems may be an alternative for cultivation in the state of Roraima. In this context, the objective of this study was to evaluate the effects of bovine biofertilizer and alley system on the production components of Sooshu hybrid cabbage. The experiment was conducted from August 2019 to July 2020 at the Agrotechnical School of the Federal University of Roraima. The treatments were arranged in randomized blocks, in split plots, with three replicates. The factorial scheme used was 2 × 5, referring to production in systems without and with alleys and five concentrations of bovine biofertilizer (0, 25, 50, 75 and 100% of the 8 L m-2 dose). After 113 days of application of the bovine biofertilizer, the following were evaluated: i) mass of the leaves that form the head; ii) number of outer leaves; iii) mass of outer leaves; iv) transverse and longitudinal diameters and v) yield. The agroforestry system had no influence on cabbage production components. Bovine biofertilizer at concentration of 63.13% promoted higher mass of leaves that form the head and yield of Sooshu hybrid cabbage.
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