Atributos edáficos de ambientes invadidos por Cryptostegia madagascariensis Bojer ex Decne. e crescimento inicial em condições de sodicidade do solo

Abstract

Biological invasion is one of the major causes of ecosystem degradation around the world. In the Northeast, the negative impacts caused by the African species Cryptostegia madagascariensis have generated concern, especially in the state of Ceará, where it is found inhabiting different soil classes. In this sense, this work was developed to characterize the physical attributes of soils invaded by C. madagascariensis in the state of Ceará, aiming to identify specific physical conditions related to the presence of the invader. Soil samples were collected in four soil classes: Planossolo Háplico, Neossolo Regolítico, Vertissolo Hidromórfico e Neossolo Flúvico, each class consisting of two environments, one invaded by C. madagascariensis, called the invaded environment and the other one occupied by the native vegetation, called the environment not invaded. In each environment, soil samples were obtained at four depths (0-5, 5-10, 10-20 and 20-30 cm), in which were determined the physical attributes: total sand, silt, clay, gravimetric moisture, natural clay, degree of flocculation, total porosity, soil density and soil penetration resistance. Data were submitted to analysis of variance in a sub-divided plot. The soil classes were studied in the plot, the environments (invaded and not invaded) in the subplot and, in the subsub-plot the depths were studied. The means were compared by the Tukey test at 5% probability. It was observed that C. madagascariensis occurs in soils with higher clay contents, the areas invaded express higher humidity, higher porosity, lower soil density and are more resistant to penetration than the soils of not invaded environments, 4.5 against 3.1 Mpa. The studied soils presented a wide textural variation, being the variability of this and other physical attributes related to the pedogenesis of each class of soil. Soil moisture may be the main physical attribute that allowed the establishment of the species and, finally, the physical conditions found allow the populations of Cryptostegia madagascariensis to complete their life cycle and advance in the invasive process by dispersing to new environments.