Navegando por Assunto "Agricultura - Aspectos ambientais"

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Acesso aberto (Open Access)
Consequências das práticas agrícolas na diversidade vegetal em Parauapebas, Pará
(Universidade Federal do Pará, 2011-04-11) SANTOS, Alessio Moreira dos; JARDIM, Mário Augusto Gonçalves; http://lattes.cnpq.br/9596100367613471
Agricultural activities in the project of nesting in the Amazon region are important in food production. The aim of this study was to identify and assess the human impact of agricultural practices on plant biodiversity of a community of small family farmers and to discuss the possibility of retaining some resistant species and useful in the tillage systems. The research was conducted at Project of Nesting Palmares II, city of Parauapebas, southeastern Pará, Brazil. The survey of plant biodiversity was conducted in 45 points on 9 demarcated family farms. Data on vegetation structure and floristic composition were analyzed using the Principal Component Analysis (PCA). Was calculated IIV (Index Importance Value) for all species found in intermediate and upper stratum. In total, considering the three strata: low, intermediate and higher, there were 707 species and their specific riches by agriculture: logged forest (77,8 ± 18,6); burned forest (65,1 ± 23,5); rice field (24 ± 2); corn field (33,6 ± 9); cassava field (31,5); clean cattle pasture (20,1 ± 8,9); invaded cattle pasture (44 ± 12,3) ; grade earth (21), young secondary forests (42,8 ± 10,7) Old secondary forests (45 ± 5,6). The species with the highest IVI were Vernonia brasiliana, Cecropia palmata, Solanum crinitum, Trema micrantha, Solanum rugosum, Oenocarpus distichus, Rollinia exsucca, Vismia baccifera, Alexa grandiflora and Pueraria phaseoloides. PCA vegetation structure indicated that the type of land use was the determining factor, linked to an opposition between high levels of richness, density and basal area of the upper stratum, high values of richness and basal area of the stratum intermediate and low values of these variables. Since the PCA of the floristic composition showed that the forest plots are opposed to other forest plots and plots of poultry, indicating differences in floristic composition even between forests. The corn field, cassava field and rice field were considered as areas that generate the most impact on biodiversity. The small size of the lots of the nesting Palmares II favors the intensive land use and deforestation accelerated. It should promote and support agroforestry practices in Project of Nesting Palmares II, to advocate farming techniques that protect natural resources, such as the conservation of tree species useful and robust in open areas. The species Pueraria phaseoloides when associated with agricultural crops, should maintain production and save the cultivated areas, functioning as green manure and minimizing degradation of cultivated areas.
Acesso aberto (Open Access)
Efeito da perda de cobertura florestal sobre a diversidade de peixes de riachos em uma zona de transição Cerrado-Amazônia
(Universidade Federal do Pará, 2019-02-28) FREITAS, Pâmela Virgolino; JIQUIRIÇÁ, Paulo Ricardo Ilha; http://lattes.cnpq.br/3392388693636935; SILVA, Karina Dias da; http://lattes.cnpq.br/2271768102150398
Currently, the expansion of the agricultural frontier in the Amazon represents a profound change in the world’s vegetation cover. This expansion causes decrease of forest cover, affecting the environmental integrity of streams, as well as the richness of associated communities. We aimed to evaluate the effects of loss of forest cover on the physical integrity of streams, and on the taxonomic and functional diversity of fish assemblages in a Cerrado-Amazon transitional zone. We sampled nine streams in the Alto Xingu river basin. The streams possess microbasins covered by different percentages of transitional Cerrado-Amazon forest and croplands. We did not detect the effect of loss of forest cover on the physical integrity of streams, and neither on fish taxonomic diversity. However, we found a negative effect on the functional diversity. The physical integrity of streams was not associated with taxonomic and functional diversity of fish assemblages. The conversion of forest areas to croplands, on the riparian zone, affects negatively the functional richness of fish assemblages, acting as an environmental filter, leading to the disappearance of species that could have performed important ecosystem functions. Furthermore, the establishment of restoring and conservation strategies of areas affected by deforestation must be a priority on all streams drainage systems, especially on the riparian zone scale, to minimize impacts on species. To understand which factors can better structure fish assemblages in streams, it is necessary to do research, that can give basis to formulate strategies for the preservation of those organisms.