Dinâmica espaço-temporal do uso e da cobertura vegetal do Maciço de Uruburetama – Ceará no período de 1987 a 2017

Abstract

The semiarid region of the Brazilian Northeast is composed of interrelated natural elements that favor the existence of landscapes with peculiar and dynamic characteristics. Among these, there is the Uruburetama massif, subhumid relief with landscape exceptions expressed both by its natural aspects and by anthropic interventions. The existence of an altitude mesoclima is a decisive factor in the maintenance of these differentiated ecological conditions, which allow the agricultural development of annual crops. This reality contributes to make landscapes of exception constant targets of socio-environmental transformations. As a result, the Uruburetama Massif, as a landscape unit of great environmental and socioeconomic relevance for the state of Ceará, was chosen as object of this research, which is to analyze the spatio-temporal dynamics of the usage and vegetation cover in the period from 1987 to 2017. It goes from the hypothesis that the relief mentioned has undergone significant landscape and degradation changes engendered by the disorderly use of its natural resources, especially in the last 30 years. The theoretical-methodological procedures are based on the approach of the integrated studies, considering, therefore, as a spatial analysis of the environmental system of the residual massif with its respective subsystems. The analysis were carried out with the help of the geotechnologies that had Geographic Information Systems (GIS) and the Remote Sensing techniques as manipulation tool and data spatialization. In order to detect changes in spatial arrangements, the methodology of supervised classification with the Maximum Likelihood Classification algorithm was used, which allowed the identification and classification of surface targets, followed by correlation, quantification and comparison of different soil uses and vegetation cover. Thus, four years (1987, 1998, 2008 and 2017) were considered as parameters for multitemporal analyses and monitoring of landscape dynamics in the face of environmental degradation conditions. The results showed that the intensive use of the soils (agricultural activities) in the different subsystems of the massif, based on the withdrawal of the native vegetation to the temporary and permanent crops, with emphasis on the planting of banana cultivation, has led to the decontamination of the mountain environment. The main changes observed in the Uruburetama massif for the 30 years were: increased caating vegetation (23.43%) followed by rock outcrops (61.57%), anthropic areas and / or exposed soil (64.73%), and water mirrors (72.72%). On the other hand, there was a reduction of dry forest vegetation (44.08%), followed by wet forest vegetation (27.27%), permanent crops (21.99%) and temporary crops (26.43%). The environmental conditions put in place reflect that the uses have been undertaken without adequate management plans, without underestimating the sustainability of the productive activities and ecological conditions (potentiality and limitations) of the environmental subsystems, thus, causing their degradation. This context only reinforces the need to adopt agricultural management practices based on the sustainability of natural resources.