Estimativa da variação espaço-temporal de áreas ocupadas por manguezal e diferentes usos e coberturas da terra no Brasil entre 2000 e 2020
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2023-03-31
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Universidade Estadual Paulista (Unesp)
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Os manguezais são ecossistemas fundamentais do ponto de vista social, econômico e ambiental. O Brasil é um dos países com maior extensão de manguezal do mundo, porém diferentes trabalhos têm mostrado que forçantes antrópicas e naturais têm suprimido áreas ocupadas por este ecossistema, ainda que em pequenas escalas geográficas. Esta pesquisa teve como objetivo estimar a variação espaço-temporal de manguezais no Brasil e diferentes usos e coberturas da terra (Land use and land cover – LULC) em diferentes escalas espaciais nas últimas duas décadas (2000-2020). Para isso, utilizamos dados dos projetos MapBiomas e Global Forest Change dentro da plataforma Google Earth Engine. Quantificamos o balanço de área de manguezal em escalas nacional, estadual e regiões (segmentos) climática-botanicamente semelhantes. Séries temporais de 20 anos foram construídas e decompostas. O banco de dados do Global Forest Change não apresentou um desempenho satisfatório na detecção de manguezais suprimidos no Brasil, quando comparado com dados previamente publicados. A partir dos dados do projeto MapBiomas, observamos que entre 2000 e 2020, o Brasil teve ganho líquido de 3982,51 km² de áreas ocupadas por manguezal. No mesmo período, 4143,43 km² de área de manguezal foi suprida, sendo que ~92% desta área pôde ser identificada com ao menos alguma das 17 LULC consideradas, as quais contribuíram diferentemente entre os estados políticos e regiões fitofisionomicamente semelhantes. As maiores conversões de manguezal ocorreram por classes de LULC não explicitamente atreladas as atividades humanas, destacando-se formação florestal e corpos d’água. Embora, comparativamente, as áreas de manguezais substituídas por classes antrópicas foram muito menores, sua identificação possibilita direcionar esforços para reduzir impactos de forçantes específicas por meio de políticas públicas e programas que lidem com uma ou pouca LULC, como pastagens, que substituiu 80,34 km² de área de manguezal preexistente. Nossos resultados corroboram evidências em escala global e no Brasil de que manguezais têm apresentado ganho líquido de área e reforçam que fatores naturais como os principais percussores de perda de manguezal. Abordagens mutli-escala como a utilizada neste estudo contribuem à gestão integrada dos manguezais, promovendo compreensão de temas que ultrapassam limites políticos. Este trabalho lança novos direcionamentos aos esforços de pesquisa, conservação e monitoramento em diferentes regiões geográficas do Brasil. Incentivamos o uso das ferramentas e dados disponibilizados neste trabalho por diferentes instituições e tomadores de decisão para ações de conservação, proteção e restauração dos manguezais brasileiros e ecossistemas adjacentes.
Mangroves are key ecosystems from social, economic, and environmental perspectives. Brazil is one of the countries with largest extension of mangroves in the world, but different studies have shown that anthropic and natural force have reduced the area occupied by this ecosystem. This research aimed to identify the temporal variation of mangroves in Brazil and different land use and land covers (LULC) at different spatial scales in the last two decades (2000-2020). We used datasets from two independent sources, MapBiomas and Global Forest Change, within Google Earth Engine platform. We quantified the mangrove area net change at national, state, and climatic-botanical regional scales (vegetation physiognomy segments). 20-year time series were constructed and decomposed. Data we obtained from Global Forest Change performed poorly in detecting suppressed Brazilian mangroves, when compared to previously published studies. Using MapBiomas data, we observed that between 2000 and 2020, Brazil had a net gain of 3982.51 km² occupied by mangrove wetlands. In the same period, 4143.43 km² of mangrove area was a suppressed, out of which ~92% could be assigned to at least some of the 17 LULC we evaluated. The major LULC classes that replaced mangrove forests were not directly associated with human activities, like forests and water bodies. Although, comparatively anthropogenic LULCs contributed less to mangrove conversion, identifying these such drivers may contribute to mangrove management and conservation as it policies and programs may tackle specific activities, like pastures which was associated with 80,34 km² of mangrove replacement. Our findings support previous studies on global and Brazil scales, as they indicate a net gain of mangroves forest and highlight that natural drivers are major LULC replacing these ecosystems. Multi-scale approaches like this study have the potential to reveal different processes, thus similar efforts are recommended for the integrated management of mangroves, promoting the understanding of issues that go beyond political boundaries. This work strengthens a global strend towards lower rates of loss of area covered with mangroves and launches new directions for research, conservation and monitoring efforts in different geographic regions of Brazil. We encourage of the tools and data made available here the use by different institutions and decision makers for conservation, protection and restoration of Brazilian mangroves and adjacent ecosystems.
Mangroves are key ecosystems from social, economic, and environmental perspectives. Brazil is one of the countries with largest extension of mangroves in the world, but different studies have shown that anthropic and natural force have reduced the area occupied by this ecosystem. This research aimed to identify the temporal variation of mangroves in Brazil and different land use and land covers (LULC) at different spatial scales in the last two decades (2000-2020). We used datasets from two independent sources, MapBiomas and Global Forest Change, within Google Earth Engine platform. We quantified the mangrove area net change at national, state, and climatic-botanical regional scales (vegetation physiognomy segments). 20-year time series were constructed and decomposed. Data we obtained from Global Forest Change performed poorly in detecting suppressed Brazilian mangroves, when compared to previously published studies. Using MapBiomas data, we observed that between 2000 and 2020, Brazil had a net gain of 3982.51 km² occupied by mangrove wetlands. In the same period, 4143.43 km² of mangrove area was a suppressed, out of which ~92% could be assigned to at least some of the 17 LULC we evaluated. The major LULC classes that replaced mangrove forests were not directly associated with human activities, like forests and water bodies. Although, comparatively anthropogenic LULCs contributed less to mangrove conversion, identifying these such drivers may contribute to mangrove management and conservation as it policies and programs may tackle specific activities, like pastures which was associated with 80,34 km² of mangrove replacement. Our findings support previous studies on global and Brazil scales, as they indicate a net gain of mangroves forest and highlight that natural drivers are major LULC replacing these ecosystems. Multi-scale approaches like this study have the potential to reveal different processes, thus similar efforts are recommended for the integrated management of mangroves, promoting the understanding of issues that go beyond political boundaries. This work strengthens a global strend towards lower rates of loss of area covered with mangroves and launches new directions for research, conservation and monitoring efforts in different geographic regions of Brazil. We encourage of the tools and data made available here the use by different institutions and decision makers for conservation, protection and restoration of Brazilian mangroves and adjacent ecosystems.
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Manguezais, Brasil, Sistemas de informação geográfica, Solo Uso, MapBiomas, Google Earth Engine, Land Use/Land Cover, Série temporal