Considerações sobre composição, estrutura e recuperação da vegetação secundária em Floresta Atlântica
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Data
2020-08-13
Autores
Souza, Ana Claudia Oliveira de
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Universidade Estadual Paulista (Unesp)
Resumo
As Florestas Tropicais, detentoras de elevada biodiversidade e endemismo, sofreram ao longo das décadas com altas taxas de desmatamento, realidade que resultou em um aumento das Florestas Secundárias Tropicais no mundo. No bioma da Mata Atlântica, encontra-se a segunda maior Floresta Tropical da América do Sul, sendo grande parte constituída por vegetação secundária decorrente de regeneração natural após diferentes tipos de uso da terra. Em Florestas Tropicais, a regeneração florestal apresenta algumas similaridades após o abandono da terra, todavia devido as peculiaridades do ecossistema e de cada tipo de uso, persiste um cenário multi dinâmico e complexo de fatores e caminhos de regeneração até que essa floresta alcance níveis similares a ambientes sem histórico de uso antrópico em termos de composição florística, estrutura e funcionalidade. Neste sentido, para aumentar o conhecimento a respeito da regeneração florestal e recuperação de seus parâmetros, após diferentes tipos de uso da terra, é necessário integrar novas abordagens que relacionem o microambiente da floresta, atributos funcionais e os diferentes estratos que compõem a vegetação, pois estas abordagens, além de pouco exploradas nos estudos científicos podem resultar em novas perspectivas em relação à temática. Dessa forma, o objetivo geral do presente trabalho foi investigar as características e recuperação do componente arbóreo (estrato adulto e regenerante) em áreas secundária de Floresta Tropical Atlântica montana com diferentes históricos de uso da terra a partir de abordagens de composição, estrutura, atributos funcionais e fatores abióticos. No primeiro capítulo, foi analisada a regeneração do componente arbóreo e a correlação com fatores químicos e luminosidade após diferentes tipos de uso da terra. Concluímos que o uso prévio da terra de corte seletivo e raso em Floresta Tropical Atlântica teve uma recuperação considerável após 45 anos de regeneração natural em termos de composição florística e estrutura da vegetação, enquanto a área de regeneração após pastagem ainda apresenta uma recuperação pequena destes parâmetros. O atual componente arbóreo entre áreas sem histórico de uso da terra e aquelas com diferentes históricos de uso correlacionam-se a um gradiente de disponibilidade de nutrientes do solo aliado a diferenças de umidade e temperatura do solo. Ainda com a finalidade de compreender as diferenças da vegetação e influências dos fatores abióticos nas áreas de estudo, o segundo capítulo teve o objetivo de atribuir quais parâmetros do solo (carbono, saturação por alumínio e temperatura) ou terreno (declividade, direção da vertente e altitude) são mais importantes e suas respectivas relações em áreas de regeneração após uso prévio da terra de corte seletivo e pastagem e também áreas sem histórico de uso prévio da terra, caracterizada pelos atributos funcionais de comprimento do fruto, densidade da madeira e síndrome de dispersão. Concluímos que as áreas diferem em termos de atributos funcionais e que, enquanto nas áreas de regeneração os parâmetros mais importantes são edáficos, na área sem histórico de uso da terra a importância é maior para atributos do terreno, adicionalmente as principais relações negativas ocorreram com parâmetros do terreno. Para finalizar, o último capítulo buscou fazer inferências a respeito da recuperação da diversidade e densidade da madeira a partir da análise de três estratos do componente arbóreo de áreas de regeneração após diferentes tipos de uso da terra. Neste, concluímos que o estudo do estrato adulto e regenerantes da Floresta Tropical Atlântica foi eficiente para verificar a recuperação destes parâmetros da vegetação, onde evidenciou-se a recuperação total da regeneração após corte seletivo e parcial na regeneração após corte raso. A área de regeneração após pastagem não apresentou recuperação em nenhum dos estratos do componente arbóreo e neste sentido uma recuperação extremamente lenta da vegetação é esperada na área. As diferentes abordagens utilizadas neste trabalho, se mostraram complementares e foram importantes para o discernimento a respeito da relevância do histórico de uso prévio da terra nas avaliações e perspectivas de recuperação da Floresta Tropical Atlântica.
Tropical Forests, which have high biodiversity and endemism, have suffered over the decades with high rates of deforestation, a reality that has recently resulted in a considerable increase in Secondary Tropical Forests in the world. In the Atlantic Forest biome, there is the second largest Tropical Forest in South America, with a large part consisting of secondary vegetation resulting from natural regeneration after different types of land use. In Tropical Forests, forest regeneration has some similarities after abandoning the land, however due to the peculiarities of the ecosystem and each type of use, a dynamic and complex scenario of regeneration factors and paths persists until this forest reaches levels similar to environments with no history of anthropic use in terms of floristic composition, structure and functionality. In this sense, to increase knowledge about forest regeneration and recovery of its parameters, after different types of land use, it is necessary to integrate new approaches that relate the forest microenvironment, functional attributes and the different strata that make up the vegetation, because these approaches, besides being little explored in scientific studies, can result in new perspectives in relation to the theme. Thus, the general objective of the present work was to address issues related to the tree's floristic composition, structure, relationships with abiotic factors and the recovery of vegetation in areas of Atlantic Tropical Secondary Forest with different land use histories; (1) selective cut (use of low impact), (2) shallow cut (use of intermediate impact) and (3) shallow cut, followed by burning of biomass and establishment of pasture (use of high impact). In the first chapter, the regeneration of the tree component and the correlation with chemical factors and luminosity after different types of land use were analyzed. We conclude that the previous use of selective and shallow cut land in the Atlantic Rain Forest had a considerable recovery after 45 years of natural regeneration in terms of floristic composition and vegetation structure, while the area of regeneration after grazing still shows a small recovery of these parameters. The current tree component between areas with no history of land use and those with different history of use correlates with a gradient of soil nutrient availability combined with differences in humidity and temperature of this abiotic factor. Still in order to understand the differences in vegetation and the influences of abiotic factors in the study areas, the second chapter aimed to assign which parameters of the soil (carbon, saturation by aluminum and temperature) or terrain (slope, aspect and altitude) are more important and their respective relationships in regeneration areas after previous use of selective-cut and pasture land and also areas with no history of previous use, characterized by functional attributes of fruit length, wood density and dispersion syndrome. We conclude that the areas differ in terms of functional attributes and that, while in the areas of regeneration the most important parameters are edaphic, in the area with no history of land use the importance is greater for attributes of the land, in addition the main negative relationships occurred with parameters of the terrain. To conclude, the last chapter sought to make inferences regarding the recovery of the diversity and density of wood from the analysis of three strata of the tree component of regeneration areas after different types of land use. In this, we conclude that the study of the adult and regenerating strata of the Atlantic Rain Forest was efficient to verify the recovery of these vegetation parameters, where the total recovery of the regeneration after selective and partial cutting in the regeneration after shallow cut was evidenced. The regeneration area after grazing did not recover in any of the strata of the tree component and in this sense an extremely slow recovery of vegetation is expected in the area. The different approaches used in this work proved to be complementary and were important for discerning the relevance of the history of previous land use in assessments and prospects for the recovery of the Atlantic Rainforest.
Tropical Forests, which have high biodiversity and endemism, have suffered over the decades with high rates of deforestation, a reality that has recently resulted in a considerable increase in Secondary Tropical Forests in the world. In the Atlantic Forest biome, there is the second largest Tropical Forest in South America, with a large part consisting of secondary vegetation resulting from natural regeneration after different types of land use. In Tropical Forests, forest regeneration has some similarities after abandoning the land, however due to the peculiarities of the ecosystem and each type of use, a dynamic and complex scenario of regeneration factors and paths persists until this forest reaches levels similar to environments with no history of anthropic use in terms of floristic composition, structure and functionality. In this sense, to increase knowledge about forest regeneration and recovery of its parameters, after different types of land use, it is necessary to integrate new approaches that relate the forest microenvironment, functional attributes and the different strata that make up the vegetation, because these approaches, besides being little explored in scientific studies, can result in new perspectives in relation to the theme. Thus, the general objective of the present work was to address issues related to the tree's floristic composition, structure, relationships with abiotic factors and the recovery of vegetation in areas of Atlantic Tropical Secondary Forest with different land use histories; (1) selective cut (use of low impact), (2) shallow cut (use of intermediate impact) and (3) shallow cut, followed by burning of biomass and establishment of pasture (use of high impact). In the first chapter, the regeneration of the tree component and the correlation with chemical factors and luminosity after different types of land use were analyzed. We conclude that the previous use of selective and shallow cut land in the Atlantic Rain Forest had a considerable recovery after 45 years of natural regeneration in terms of floristic composition and vegetation structure, while the area of regeneration after grazing still shows a small recovery of these parameters. The current tree component between areas with no history of land use and those with different history of use correlates with a gradient of soil nutrient availability combined with differences in humidity and temperature of this abiotic factor. Still in order to understand the differences in vegetation and the influences of abiotic factors in the study areas, the second chapter aimed to assign which parameters of the soil (carbon, saturation by aluminum and temperature) or terrain (slope, aspect and altitude) are more important and their respective relationships in regeneration areas after previous use of selective-cut and pasture land and also areas with no history of previous use, characterized by functional attributes of fruit length, wood density and dispersion syndrome. We conclude that the areas differ in terms of functional attributes and that, while in the areas of regeneration the most important parameters are edaphic, in the area with no history of land use the importance is greater for attributes of the land, in addition the main negative relationships occurred with parameters of the terrain. To conclude, the last chapter sought to make inferences regarding the recovery of the diversity and density of wood from the analysis of three strata of the tree component of regeneration areas after different types of land use. In this, we conclude that the study of the adult and regenerating strata of the Atlantic Rain Forest was efficient to verify the recovery of these vegetation parameters, where the total recovery of the regeneration after selective and partial cutting in the regeneration after shallow cut was evidenced. The regeneration area after grazing did not recover in any of the strata of the tree component and in this sense an extremely slow recovery of vegetation is expected in the area. The different approaches used in this work proved to be complementary and were important for discerning the relevance of the history of previous land use in assessments and prospects for the recovery of the Atlantic Rainforest.
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Palavras-chave
Mata Atlântica, Floresta Ombrófila Densa, Regeneração natural, Densidade da madeira, Uso da terra, Atlantic forest, Dense Ombrophilous Forest, Natural regeneration, Wood density, Land use