Rafael Cámara Artigas

the Caatinga and desertification

High deforestation in the Caatinga Biome has been generating processes of desertification in several areas, directly altering the biota, the microclimate and the soils, being essential the development of research techniques able to incorporate information which identify the state of natural resources, pointing their relationships and some paths to be taken for an effective intervention which may generate the recovery and sustainable use of land in this environment. The MTLFC consists of a set of techniques used in Brazil for the first time to analyze areas subjected to desertification, presenting biogeographic, climatological, geomorphological and hydrological indicators. By applying the method in an area of the city of Sao Domingos do Cariri (PB), it has been identified a very low plant diversity (13 species and 489 individuals), dominance of a few species (5) and low abundance, with the largest number of individuals in tall shrub and shrub strata, caused by the excessive removal of vegetation, fires and continuous use by the goats. The Water Balance was negative so that it indicated that the vegetative activity depends on hidden precipitation. The soils have presented surface crust of an anthropic origin, making edaphic aridity even more pronounced, associated with low fertility levels, particularly potassium and organic matter.

Niveaux marins et karsts à Saint Domingue

La secuencia dc niveles marinos y karstificacion asociada a las terrazas coralinas de les costas de la Republica Dominicana, pone de manifiesto una dinâ-mica cuaternaria ligada a los cambios climâticos con repercusion directa en las variaciones del nivel del mar en el Caribe, correlacionables con los registros isotopicos del oxigeno. La evolucion analizada abarca los ultimos 400 000 anos, limite cronometri-co del U/Th, y pone de manifiesto la importances de los Estados 1, 5 y 7 (interglaciales) en la conformacion de las terrazas coralinas. Las diferencias de la karstificacion entre periodos antiguos del Pleistoceno y mas recientes, se plantean derivadas de una posible evolucion del sistema morfoclima-tico intertropical hacia mis seco.