Modelagem da conversão de ecossistemas no contexto da economia: uma análise aplicada no município de Moju, nordeste do estado do Pará.

Abstract

The dynamics of deforestation in the state of Pará has been for decades induced by developmental public policies, and by fulfillment of a national agenda that has engendered several scenarios in the region, and let to the increase in conversions of ecosystems, the use of natural resources, population growth by migration, and the consolidation of homogeneous productive activities. The understanding ofthis occupation process through the establishment of productive dynamics was different in the state and points to many specificities, which does not allow its use for the understanding of the dynamics at a local (city) levei. Therefore, the present study analyzes the determining factors of forest conversions in the city of Moju and their effects on the living conditions in rural areas, specifically the identification of the main activities that cause deforestation, vector dimensions at local scale and the changes originated by this dynamics explain the specificities at the local (city) levei. Based on Multivariate Analysis- MA, using the Method of Principal Components (MCP), the structure ofthe factors that represent the indicators was identified, and the indicators were subsequently transformed into independent variables using Multiple Linear Regression Model- MRLM, proposed to analyze the dynamics of ecosystem conversions. A supervised analysis of SPOT satellite imagery with a resolution of 2.5 mts allowed the classification and identification of the referred factors and the establishment of the main zones of conversions. The in situ application of a questionnaire for understanding the perception of changes in the rural area prometes social discussion of the analyzed dynamics and constitutes the model for assessing transformations in rural communities. The recent deforestation in the city of Moju favors agricultural projects with participation of foreign capital and monocultures, imposing new zones for forest conversions with reduced gains and high rates of migrations between the communities.

In discussions on deforestation in the Amazon and, in particular, in the state of Pará, livestock has been identified as the main activity responsible for the conversion of primary forests and the opening of new frontiers ofproduction. This study assesses the validity ofthese assertions and assumes the presence of strong interactions between the activities as a theoretical assumption. In general, it investigates the common variability that sizes the dynamics of deforestation and estimates a deforestation rate for the state - IDE, and specifically identifíes the factor loads that reveal deforestation pattems according to the main productive activities. The use of multivariate techniques through the Method of Principal Components - MCP showed that agricultural and livestock activity had a significant impact on deforestation and determined the spatial location of other activities that contribute to the same problem, no longer characterizing livestock as the only cause of deforestation in the state.

The considerations about the dynamics of deforestation in the state of Pará-Amazon -Brazil have indicated statistical results consistent with its territorial dimension. However, for an analysis of forest conversions at local levei, other factors emerge as relevant, and this would be associated to a complex and uncontrolled environment, with multidimensional input structures. The proper understanding ofthe impact ofthe productive activities is associated to the purpose of determining which are the latent variables that identify, measure and explain the dynamics ofrecent deforestation in the city of Moju, based on Multiple Linear Regression Model - MRLM that allows estimating the explanatory parameters. Exploratory Factor Analysis - EFA was the technique used to identify the common variability of data with emphasis on total variance using the Method of Principal Components - MCP, and adopting orthogonal Varimax rotation to isolate the variables to the factor and using scores as regressors. The model fit was perfect and showed a high explanatory power (R2 = 99.20), of the explained deforestation variable, and with significances below 1% for the explanatory variables.

The expansion of economic activities in the city of Moju, between 2000 and 2010, showed a sharp increase in production in different zones of the rural area, with different types of occupations, and concomitantly, large-scale monocultures. Some cultures received noticeably more resources, supported by International capitais and public policies aimed to meet the increase in intemational demand. The expansion of the activities to areas of high environmental fragility, the effect of the cropping system of altemative cultures, and especially the process of conversion of ecosystems were analyzed for an understanding of the spatial dynamics of deforestation. The new areas incorporated to the expansion process in the analyzed period, the Identification of spaces with predominance of monocultures and the growth zones measured in Km2, of the productive areas of the main determining factors of deforestation, contributed to the achievement of the general objective of this article. Supervised analysis of SPOT satellite imaging with a resolution of 2.5 mts and the vector crossing of the evolution of the deforestation shapes of INPE between 2000 and 2010, using SPRING 5.2 software, with the aid of various thematic maps, allowed the classification and identification of classes, and the establishment of the main zones of conversions in the rural area. They also explained the expansion ofthe culture of palm oil as the main activity in the rural environment, in fragile areas, and the system of alternative cultures with accelerated changes in the ecosystems ofthe city.

The characteristics ofthe closer ties between man and nature, with direct reflexes on the use of natural resources, aliows an objective analysis of the distribution of deforestation and its impacts on the living conditions in rural zone of the city of Moju. The profde of the distribution of income and the conditions of access to public services are some variables that were adjusted to correctly interpret the changes occurred in the period. The application of field research at the rural communities and the use ofmultivariate analysis made it possible to identify the main factors that explain the living conditions in Moju, the magnitude of their contributions when geographical spaces are compared. Thus, the spatially identified factor loading scores were treated as estimators in the Geographically Weighted Regression model - GWR that is aimed to quantitatively express the overall relations and spatial changes between the selected variables. The unequal distribution of income and the access to public services were geographically defined, leading to the conclusion that the proximity to large-scale projects did not constitute a necessary condition for improving the living conditions of the population, which, on the contrary, has worsened after the implementation of such projects. The systematic impacts of deforestation explained the deterioration in living conditions over time in the rural zone of Moju.