Dinâmica florestal e estoque de carbono em fragmentos de Mata Atlântica
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2024-02-29
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Universidade Estadual Paulista (Unesp)
Resumo
A Mata Atlântica brasileira (BAF), reconhecida como um hotspot de biodiversidade, encontra-se em grave ameaça devido à fragmentação de sua paisagem, resultado de impactos ambientais. A diversidade existente nos fragmentos apresenta desafios consideráveis na identificação e mensuração dos recursos florestais, incluindo o estoque de carbono presente tanto acima quanto abaixo do solo. Aqui, avaliamos a dinâmica florestal, estoque de carbono acima e abaixo do solo, além da dinâmica de carbono em fragmentos de Mata Atlântica, ao longo de uma antroposequência caracterizada por históricos decrescentes de perturbação humana: secundária (SF) > perturbada (DF) > floresta tardia (LF). Utilizamos dados provenientes de 18 parcelas, totalizando 3,6 hectares, distribuídas ao longo de um gradiente de perturbação. Dessas, 4 parcelas estão localizadas em áreas de Floresta Secundária, 8 em Floresta Perturbadas e 6 em Florestas Tardia. Realizamos dois inventários, em 2017 e 2022, em cada um dos quais mensuramos todas as árvores vivas e mortas com DAP≥ 5 cm, contabilizando sobreviventes, recrutas e indivíduos mortos entre os intervalos. Além disso, determinamos parâmetros demográficos, como taxas de recrutamento, crescimento e mortalidade do caule, juntamente com a área basal. Para o estoque de carbono acima do solo, estimamos os estoques na biomassa aérea, madeira morta e serrapilheira. Abaixo do solo, determinamos os estoques de carbono em diferentes profundidades (0-20, 20-40, 40-60, 60-80, 80-100 cm). Na dinâmica do carbono, avaliamos as mudanças nos estoques de carbono em árvores vivas, serrapilheira, madeira morta, carbono total e carbono orgânico do solo até um metro de profundidade, bem como o recrutamento e perda de carbono. Descobrimos que as taxas de recrutamento, crescimento e rotatividade de espécies da Floresta secundária que sofreram intensamente atividades antrópicas foi significativamente maior do que aqueles que sofreram menos perturbações. A mortalidade de caule e perda de área basal foi mais significativa a medida que diminuía o gradiente de perturbação com destaque a Floresta tardia. A Floresta tardia destacou-se com o maior estoque de carbono nas árvores vivas e com médias de 99,0 ± 8,6 Mg ha-1. No estoque de carbono do solo até um metro de profundidade, a Floresta perturbada e Floresta tardia apresentaram o maior estoque de carbono com 182,3 ± 28,1 Mg ha-1 e 176,5 ± 19,4 Mg ha-1 respectivamente. Enquanto, o estoque de carbono total apresentou uma tendência crescente (p < 0.05) com a diminuição do gradiente de perturbação humana (SF → DF → LF). Observamos mudanças significativas no estoque de carbono das árvores vivas (63,3 Mg ha-1 em 2017 para 75,2 Mg ha-1 em 2022) e no solo (121,4 Mg ha-1 em 2017 para 136,5 Mg ha-1 em 2022 na Floresta Secundária. A dinâmica anual do carbono nas árvores foi mais acentuada na Floresta Secundária, devido ao recrutamento (1,0 Mg ha-1). A Floresta Secundária destacou-se no estoque de carbono total, com aumento significativo (p<0.05) de 27,3 Mg ha-1. A influência negativa da perturbação humana torna evidente que os fragmentos florestais com menor grau de interferência ou ausência dela desempenham um papel significativo no armazenamento dos estoques de carbono, enquanto esse papel diminui à medida que o grau de perturbação aumenta. Os estudos de estoque de carbono em fragmentos de Mata Atlântica com diferentes graus de perturbação humana são de extrema importância, pois não apenas evidenciam a capacidade dessas florestas em mitigar as mudanças climáticas, atuando como sumidouros de carbono, mas também destacam seu papel na conservação da biodiversidade e na prestação de diversos serviços ecossistêmicos.
The Brazilian Atlantic Forest (BAF), recognized as a biodiversity hotspot, is under severe threat due to the fragmentation of its landscape, a consequence of environmental impacts. The diversity within the fragments poses considerable challenges in identifying and measuring forest resources, including the carbon stock both above and below ground. Here, we assess the forest dynamics, carbon stock above and below ground, and carbon dynamics in fragments of the Atlantic Forest along an anthroposequence characterized by decreasing human disturbance histories: secondary forest (SF) > disturbed forest (DF) > late forest (LF). We utilized data from 18 plots, totaling 3.6 hectares, distributed along a disturbance gradient. Of these, 4 plots are situated in areas of Secondary Forest, 8 in Disturbed Forests, and 6 in Late Forests. We conducted two inventories, in 2017 and 2022, in each of which we measured all living and dead trees with DBH≥ 5 cm, accounting for survivors, recruits, and individuals dead between intervals. Additionally, we determined demographic parameters, such as recruitment, growth, and stem mortality rates, along with basal area. For the aboveground carbon stock, we estimated stocks in aerial biomass, dead wood, and litter. Below ground, we determined carbon stocks at different depths (0-20, 20-40, 40-60, 60-80, 80-100 cm). In carbon dynamics, we assessed changes in carbon stocks in live trees, litter, dead wood, total carbon, and soil organic carbon down to one meter depth, as well as carbon recruitment and loss. We found that the rates of recruitment, growth, and species turnover in the Secondary Forest that underwent intensive anthropogenic activities were significantly higher than those subjected to less disturbance. Stem mortality and loss of basal area were more significant as the disturbance gradient decreased, with Late Forest standing out. The Late Forest stood out with the highest carbon stock in live trees and averaged 99.0 ± 8.6 Mg ha-1. In the soil carbon stock down to one meter depth, the Disturbed Forest and Late Forest showed the highest carbon stock with 182.3 ± 28.1 Mg ha-1 and 176.5 ± 19.4 Mg ha-1, respectively. Meanwhile, the total carbon stock showed an increasing trend (p < 0.05) with decreasing human disturbance gradient (SF → DF → LF). We observed significant changes in the carbon stock of live trees (63.3 Mg ha-1 in 2017 to 75.2 Mg ha-1 in 2022) and in the soil (121.4 Mg ha-1 in 2017 to 136.5 Mg ha-1 in 2022) in the Secondary Forest. The annual carbon dynamics in trees were more pronounced in the Secondary Forest, due to recruitment (1.0 Mg ha-1). The Secondary Forest stood out in the total carbon stock, with a significant increase (p<0.05) of 27.3 Mg ha-1. The negative influence of human disturbance makes it evident that forest fragments with lower interference or its absence play a significant role in storing carbon stocks, while this role diminishes as the degree of disturbance increases. Studies on carbon stocks in Atlantic Forest fragments with different degrees of human disturbance are of utmost importance, as they not only highlight the ability of these forests to mitigate climate change by acting as carbon sinks but also emphasize their role in biodiversity conservation and the provision of various ecosystem services.
The Brazilian Atlantic Forest (BAF), recognized as a biodiversity hotspot, is under severe threat due to the fragmentation of its landscape, a consequence of environmental impacts. The diversity within the fragments poses considerable challenges in identifying and measuring forest resources, including the carbon stock both above and below ground. Here, we assess the forest dynamics, carbon stock above and below ground, and carbon dynamics in fragments of the Atlantic Forest along an anthroposequence characterized by decreasing human disturbance histories: secondary forest (SF) > disturbed forest (DF) > late forest (LF). We utilized data from 18 plots, totaling 3.6 hectares, distributed along a disturbance gradient. Of these, 4 plots are situated in areas of Secondary Forest, 8 in Disturbed Forests, and 6 in Late Forests. We conducted two inventories, in 2017 and 2022, in each of which we measured all living and dead trees with DBH≥ 5 cm, accounting for survivors, recruits, and individuals dead between intervals. Additionally, we determined demographic parameters, such as recruitment, growth, and stem mortality rates, along with basal area. For the aboveground carbon stock, we estimated stocks in aerial biomass, dead wood, and litter. Below ground, we determined carbon stocks at different depths (0-20, 20-40, 40-60, 60-80, 80-100 cm). In carbon dynamics, we assessed changes in carbon stocks in live trees, litter, dead wood, total carbon, and soil organic carbon down to one meter depth, as well as carbon recruitment and loss. We found that the rates of recruitment, growth, and species turnover in the Secondary Forest that underwent intensive anthropogenic activities were significantly higher than those subjected to less disturbance. Stem mortality and loss of basal area were more significant as the disturbance gradient decreased, with Late Forest standing out. The Late Forest stood out with the highest carbon stock in live trees and averaged 99.0 ± 8.6 Mg ha-1. In the soil carbon stock down to one meter depth, the Disturbed Forest and Late Forest showed the highest carbon stock with 182.3 ± 28.1 Mg ha-1 and 176.5 ± 19.4 Mg ha-1, respectively. Meanwhile, the total carbon stock showed an increasing trend (p < 0.05) with decreasing human disturbance gradient (SF → DF → LF). We observed significant changes in the carbon stock of live trees (63.3 Mg ha-1 in 2017 to 75.2 Mg ha-1 in 2022) and in the soil (121.4 Mg ha-1 in 2017 to 136.5 Mg ha-1 in 2022) in the Secondary Forest. The annual carbon dynamics in trees were more pronounced in the Secondary Forest, due to recruitment (1.0 Mg ha-1). The Secondary Forest stood out in the total carbon stock, with a significant increase (p<0.05) of 27.3 Mg ha-1. The negative influence of human disturbance makes it evident that forest fragments with lower interference or its absence play a significant role in storing carbon stocks, while this role diminishes as the degree of disturbance increases. Studies on carbon stocks in Atlantic Forest fragments with different degrees of human disturbance are of utmost importance, as they not only highlight the ability of these forests to mitigate climate change by acting as carbon sinks but also emphasize their role in biodiversity conservation and the provision of various ecosystem services.
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Palavras-chave
Antropização, Dinâmica florestal, Estoque de carbono, Florestas secundárias, Anthropization, Forest dynamics, Carbon stock, Secondary forest
Como citar
JUSTINO, S. T. J. Dinâmica florestal e estoque de carbono em fragmentos de Mata Atlântica. 2024. Tese (Doutorado em Ciência Florestal) – Faculdade de Ciências Agronômicas, Universidade Estadual Paulista, Botucatu, 2024.