Elaboração de um índice de vulnerabilidade ambiental dos fragmentos florestais da mata atlântica
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Data
2021-01-08
Autores
Sousa, Jocy Ana Paixão de
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Universidade Estadual Paulista (Unesp)
Resumo
O desequilíbrio nos ecossistemas, decorrentes das transformações antrópicas, afeta principalmente os ambientes florestais, como também a fauna associada e o bem-estar da população humana, devido ao comprometimento dos serviços ecossistêmicos. Portanto, esta pesquisa apresenta como objetivo desenvolver um Índice de Vulnerabilidade Ambiental de Fragmentos Florestais (IVAFF) considerando indicadores ambientais que representem as condições de conservação e preservação dos remanescentes florestais da Mata Atlântica presentes na Bacia Hidrográfica do Rio Sorocabuçu (BHRS). Foi realizada a classificação dos tipos de cobertura e uso da terra para os anos de 2010 e 2019. Posteriormente obteve-se três indicadores, sendo estes, Indicador de Risco de Extinção de Fragmentos Florestais (IREFF), Indicador de Sustentabilidade de Fragmentos Florestais (ISFF) e o Indicador de Risco de Incêndios Florestais (IRIF). Para o IREFF utilizou-se as métricas da ecologia da paisagem (tamanho e isolamento) e o Índice de Exposição Antrópica (IEA), o ISFF considerou as variáveis conservação, antrópica e biofísica, o IRIF as variáveis foram divididas em antrópica, topográfica, de cobertura vegetal e climática. A partir desses indicadores foi obtido o IVAFF. A obtenção dos indicadores foi embasada na Análise Hierárquica de Processo (AHP), que também foi utilizada para estruturar o IVAFF. Quanto aos tipos de cobertura e uso da terra constatou-se que a bacia apresenta subclasses predominantemente do tipo floresta, área vegetacional perturbada e cultura temporária, com um destaque para as florestas, que se concentram de leste a oeste da bacia, cujo ano de 2010 correspondiam aproximadamente 52% da área total da bacia e em 2019 a 45,72%. Em 2010 verificou um total de 235 fragmentos florestais, enquanto em 2019 contabilizou-se 195, havendo uma perda de 40 fragmentos, no qual a maioria eram menores que 10 hectares. O IREFF mostrou que para 2010 as classes alto e muito alto apresentaram mais fragmentos florestais com risco de extinção, onde em 2019 estas classes foram as únicas que apresentaram fragmentos extintos, o mesmo foi observado para a predição de 2029. Quanto ao ISFF notou-se que a maioria dos fragmentos florestais apresentam uma sustentabilidade considerada média, o que corresponde a 49% dos fragmentos, predominando aqueles de porte pequeno e médio. Para o IRIF a classe alto prevaleceu, representando cerca de 82% dos fragmentos, sendo que a maioria deles são de tamanho pequeno ou médio. Pode-se concluir que possivelmente as culturas temporárias são as principais responsáveis pela transformação da paisagem da BHRS e que todas as interferências na paisagem contribuíram para que a maioria dos fragmentos da bacia se tornassem pequenos, isolados e marcados por formatos irregulares, sobretudo com uma maior exposição a ação antrópica. IREFF mostrou que os fragmentos com chances de serem extintos são das classes de risco de alto e muito alto. No ISFF o fato de não ter se constatado fragmento de tamanho grande e muito grande que apresentasse uma sustentabilidade considerada muito baixa ou baixa é uma sinalização de que os fatores utilizados para a composição desse indicador são adequados. O IRIF mostrou que entre as sub-bacias que apresentam elevado risco de incêndios, as sub-bacias 1, 7 e 8, devem ser priorizadas para a tomada medidas urgentes, uma vez que são as regiões com o risco de incêndios considerados muito alto. A metodologia para se obter o IVAFF se mostrou adequada, obtendo-se uma exatidão global de 85%. Constatou-se que a maioria dos fragmentos se encontram com média ou alta vulnerabilidade, cerca de 51% e 36%, respectivamente. Isso confirma o que foi verificado nos indicadores, que a maioria dos fragmentos necessitam de medidas que visem a sua conservação ou recuperação, sendo as atividades antrópicas um dos maiores fatores de pressão sobre os fragmentos.
The imbalance in ecosystems, resulting from anthropic changes, mainly affects forest environments, as well as the associated fauna and the well-being of the human population, due to the compromise of ecosystem services. Therefore, this research aims to develop an Environmental Vulnerability Index of Forest Fragments (EVIFF) considering environmental indicators that represent the conservation and preservation conditions of the forest remnants of the Atlantic Forest present in the Sorocabuçu River Watershed (SRW). The classification of the types of cover and land use was carried out for the years 2010 and 2019. Subsequently, three indicators were obtained, namely, Forest Fragment Extinction Risk Indicator (FFERI), Forest Fragment Sustainability Indicator (FFSI) and the Forest Fire Risk Indicator (FFRI). For FFERI the metrics of landscape ecology (size and isolation) and the Anthropic Exposure Index (AEI) were used, the FFSI considered the conservation, anthropic and biophysical variables, FFRI the variables were divided into anthropogenic, topographic, vegetation cover and climate. From these indicators, EVIFF was obtained. Obtaining the indicators was based on the Hierarchical Process Analysis (AHP), which was also used to structure the EVIFF. Regarding the types of cover and land use, it was found that the watershed has subclasses predominantly of the forest type, disturbed vegetation area and temporary culture, with an emphasis on forests, which are concentrated from east to west of the watershed, whose year of 2010 corresponded to approximately 52% of the total area of the watershed and in 2019 to 45.72%. In 2010, there were a total of 235 forest fragments, while in 2019 there were 195, with a loss of 40 fragments, most of which were smaller than 10 hectares. The FFERI showed that for 2010 the high and very high classes had more forest fragments at risk of extinction, where in 2019 these classes were the only ones that had extinct fragments, the same was observed for the 2029 prediction. As for the FFSI, it was noted that the majority of forest fragments have a sustainability considered average, which corresponds to 49% of the fragments, predominantly those of small and medium size. For FFRI, the upper class prevailed, representing about 82% of the fragments, most of which are small or medium in size. It can be concluded that possibly the temporary cultures are the main responsible for the transformation of the SRW landscape and that all the interferences in the landscape contributed for the majority of the fragments of the watershed to become small, isolated and marked by irregular shapes, above all with a greater exposure to anthropic action. FFERI showed that the fragments with a chance of becoming extinct are in the high and very high risk classes. At FFSI, the fact that there was no fragment of a large or very large size that presented a sustainability considered to be very low or low is a sign that the factors used for the composition of this indicator are adequate. FFRI showed that among the sub-watershed that present a high risk of fires, sub-watersheds 1, 7 and 8, should be prioritized for urgent action, since they are the regions with the risk of fires considered very high. The methodology for obtaining EVIFF proved to be adequate, obtaining an overall accuracy of 85%. It was found that the majority of the fragments are with medium or high vulnerability, about 51% and 36%, respectively. This confirms what was verified in the indicators, that most of the fragments need measures aimed at their conservation or recovery, with human activities being one of the biggest pressure factors on the fragments.
The imbalance in ecosystems, resulting from anthropic changes, mainly affects forest environments, as well as the associated fauna and the well-being of the human population, due to the compromise of ecosystem services. Therefore, this research aims to develop an Environmental Vulnerability Index of Forest Fragments (EVIFF) considering environmental indicators that represent the conservation and preservation conditions of the forest remnants of the Atlantic Forest present in the Sorocabuçu River Watershed (SRW). The classification of the types of cover and land use was carried out for the years 2010 and 2019. Subsequently, three indicators were obtained, namely, Forest Fragment Extinction Risk Indicator (FFERI), Forest Fragment Sustainability Indicator (FFSI) and the Forest Fire Risk Indicator (FFRI). For FFERI the metrics of landscape ecology (size and isolation) and the Anthropic Exposure Index (AEI) were used, the FFSI considered the conservation, anthropic and biophysical variables, FFRI the variables were divided into anthropogenic, topographic, vegetation cover and climate. From these indicators, EVIFF was obtained. Obtaining the indicators was based on the Hierarchical Process Analysis (AHP), which was also used to structure the EVIFF. Regarding the types of cover and land use, it was found that the watershed has subclasses predominantly of the forest type, disturbed vegetation area and temporary culture, with an emphasis on forests, which are concentrated from east to west of the watershed, whose year of 2010 corresponded to approximately 52% of the total area of the watershed and in 2019 to 45.72%. In 2010, there were a total of 235 forest fragments, while in 2019 there were 195, with a loss of 40 fragments, most of which were smaller than 10 hectares. The FFERI showed that for 2010 the high and very high classes had more forest fragments at risk of extinction, where in 2019 these classes were the only ones that had extinct fragments, the same was observed for the 2029 prediction. As for the FFSI, it was noted that the majority of forest fragments have a sustainability considered average, which corresponds to 49% of the fragments, predominantly those of small and medium size. For FFRI, the upper class prevailed, representing about 82% of the fragments, most of which are small or medium in size. It can be concluded that possibly the temporary cultures are the main responsible for the transformation of the SRW landscape and that all the interferences in the landscape contributed for the majority of the fragments of the watershed to become small, isolated and marked by irregular shapes, above all with a greater exposure to anthropic action. FFERI showed that the fragments with a chance of becoming extinct are in the high and very high risk classes. At FFSI, the fact that there was no fragment of a large or very large size that presented a sustainability considered to be very low or low is a sign that the factors used for the composition of this indicator are adequate. FFRI showed that among the sub-watershed that present a high risk of fires, sub-watersheds 1, 7 and 8, should be prioritized for urgent action, since they are the regions with the risk of fires considered very high. The methodology for obtaining EVIFF proved to be adequate, obtaining an overall accuracy of 85%. It was found that the majority of the fragments are with medium or high vulnerability, about 51% and 36%, respectively. This confirms what was verified in the indicators, that most of the fragments need measures aimed at their conservation or recovery, with human activities being one of the biggest pressure factors on the fragments.
Descrição
Palavras-chave
Indicadores ambientais, Transformação da paisagem, Ecossistemas Florestais, Biodiversidade