Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Titre : Cariri paraibano : do silêncio do lugar à desertificação

Auteur : Souza, Bartolomeu Israel de

Université de soutenance : Universidade Federal do Rio Grande do Sul

Grade : Doutorado 2008

Résumé
In the present study, the mapping of the desertification process of Cariri region was executed, considering the historic process of occupation and population expansion in this region, the vegetation qualitative analyses through bioindicators (diversity, density and extracts) and the remote sensoring and geoprocessing. Among our results it was verified that : nowadays (2005/2006), 77.4% of the region has been reached by the desertification process in all analyzed levels (Moderate, High and Very High) ; from 1989 to 2005/2006, there was an increase nearly 14.6% of this kind of degradation ; during the study period, the higher desertification rate occurred on Western Cariri ; in order to identify and quantify the desertification, the use of satellite images near the rainy season presented more satisfactory responses than dry season images ; according to the results observed in the field, the satellite image analysis through the use of the Non-Supervised classification had a better response than the NDVI. The areas where the desertification process is more accentuated and concentrated are located in the areas near the greatest hydrographic basins of the region (Paraíba and Taperoá rivers), by means of the presence of expressive fertile plains which benefited the human occupation process that has been developed through centuries in Cariri. More recently, the Public Regulations, particularly the incentives to goat culture (caprinocultura activity), have exerted a fundamental role in the increase of desert areas in quantity and intensity, because of the semi-extensive way of raising the animals, associated with the agrarian structure alterations and the overgrazing. Laboratory analyses executed to identify possible soil alterations, as consequence of desertification, showed problems as the elevation of salinity in irrigated areas, which has partially affected the agriculture. However, in relation to soil fertility, even in areas that lack caatinga vegetations, modifications in this parameter were not found, which can be explained by the protection against the hidric erosion, that is provided by the Desert Floor and the argillaceous material resistance which constitutes the aggregated elements present in the superficial horizon of soils of the region. In this case, despite the vegetation degradation, it is possible to recuperate these areas by virtue of the fertility of the soils.

Assunto(s) : Cariri Ocidental (PB : Microrregião), Cariris velhos, Geografia física, Desertificação, Desertification, Occupation process, Sensoriamento remoto, Geoprocessamento, Mapping, Soils

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