Temporal dynamics of land use and cover in Paurá Lagoon region, Middle Coast of Rio Grande do Sul (RS), Brazil

Abstract

Land use and land cover studies can help in the monitoring and management of important landscapes and priority areas for conservation, especially those threatened by anthropogenic processes. The Middle Coastal region of Rio Grande do Sul (RS) – the southernmost State of Brazil, comprises a variety of ecosystems recognized as highly important for conservation. Threats to their integrity include Pinus sp forestry and its rapid invasiveness over natural areas, like the surroundings of Paurá Lagoon (-31°34’, -51°17’ and -31°35’, -51º18’). Through remote sensing and field observations, the present study sought to identify, quantify and map the main thematic classes of land use and coverage in the vicinities of the Paurá Lagoon. Changes and influencing factors over 26 years were studied using four Landsat TM 5 satellite images, dated from 06/02/1985, 30/07/1996, 23/05/2006 and 28/10/2011. Besides lagoon water, eight other thematic classes were identified and quantified: Dune, Vegetated Dune, Restinga Forest, Wet Grassland/Marsh, Sandy Field/Exposed Soil, Pasture Field, Forestry and Forested Dune. Various relevant changes in the landscape were observed, measured and compared over time, including the occupation of the legally-bound permanent preservation areas (PPA) by Pinus sp and its subsequent partial disposal in compliance with environmental licensing. Creation of a local conservation unit is recommended. Measures are suggested for an integrated management of this coastal environment, enabling preservation of the landscape and its mosaic of ecosystems in conjunction with sustainable land use. Information raised in this paper may assist planning and decision-making for licensing, management and monitoring of the Paurá Lagoon region and other similar important coastal regions.