AVALIAÇÃO ESPAÇO-TEMPORAL DOS MANGUEZAIS NO ENTORNO DO PARQUE NACIONAL DOS LENÇÓIS MARANHENSES (BRASIL)

Abstract

The Lençóis Maranhenses mangroves are highly productive and provide many services ecosystem services, such as improving water quality, reducing coastal erosion and supporting networks coastal foodstuffs, as well as forest products used in local economic development. Therefore, the evaluation of mangroves and their distribution, related to the dynamics of dunes that make up the region, are crucial to providing decision makers with the tools they need to the elaboration of policies and strategies aimed at the management and conservation of mangrove forests in the eastern coastal region. The objective of this work was to evaluate the distribution of forests in the years of 1985 and 2019 and investigate the impacts, as well as the loss, stability and gain of these forests of mangrove as a result of the dune dynamics in the region around Lençóis Maranhenses. Ours The results revealed that the mangrove forest cover in the study area showed a reduction net of 3.72 km2, identified in (2019 – 1985). It was also identified a dune increase in around 15.34 km2, considering the two years analyzed, with more than 100% increase in sand over the mangrove forest around Lençóis Maranhenses. A detailed gain analysis, stability and loss of each class, mangrove and dune, demonstrated areas of dune migration, burial and consequent death of the mangrove for the years studied here. The total forest area of mangrove lost was from 8.27 km2 in 1985 to 2019 (8% loss), with significant stability of 26.32 km2 of mangrove area (26% stability). On the other hand, it was possible to observe the emergence of new areas of mangrove forest, with approximately 3.74 km2 in 1985 to 2019 (4% of gain). The calculation of the MMRI vegetation index (Modular Mangrove Recognition Index), allowed the visualization of other small strips of mangrove, near the region of the mouth of the Preguiças River, in areas not demonstrated or classified by Mapbiomas data, confirming the reliability and effectiveness of Mapbiomas land use and land cover data, around 94.80%, according to the literature. In addition, it was found that the increase in the dune field, which mainly affects the villages of Caburé and Praia do Atins, present greater fragility of the mangrove, with records of in situ observations of senescent species. The increase in sand hills is directly related to the trade wind regimes, which characterize the region and which have displaced large part of the sandy sediment from the coast to the continent, with greater intensity recorded in the year 1985. Thus, measures that contribute to the conservation of mangrove forests in the region, both with measures to control climate change in general and still anthropic, will have a positive reflection for the mangrove forests of the study area.