Efeitos da cobertura de adubação verde no sucesso da restauração por semeadura direta (muvuca de sementes) no bioma Mata Atlântica do sudeste
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Data
2022-02-11
Autores
Pagoto, Joyce Meireles
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
O bioma Mata Atlântica, um hotspot de biodiversidade, perdeu a maior parte de sua cobertura vegetal nativa. Técnicas ativas de restauração, como a semeadura direta, são uma importante estratégia para beneficiar a formação da estrutura florestal e inibir a invasão de gramíneas exóticas, que é um impedimento para muitos projetos de restauração. A semeadura direta (popularmente chamada de “muvuca de sementes”) baseia-se em uma mistura de alta densidade de sementes de grandes grupos funcionais/ecológicos (nativos e exóticos “adubo verde”) semeadas em solo, covas ou linhas bem preparadas. A principal vantagem ecológica dos locais de semeadura direta é que eles apresentam maior densidade de plantas nos estágios iniciais, o que pode beneficiar a formação da estrutura florestal e inibir a invasão de gramíneas exóticas. A semeadura combinada com a adubação verde vem sendo utilizada como estratégia de recobrimento inicial rápido em solos degradados, auxiliando no controle de processos erosivos e na melhoria das condições do solo. Assim, neste estudo objetivamos investigar o papel da adubação verde na cobertura de espécies invasoras e no cultivo de plântulas de espécies nativas em locais de semeadura direta no bioma Mata Atlântica Sudeste. Nossa hipótese é que a adubação verde suprimiria a cobertura de gramíneas exóticas e beneficiaria o cultivo de mudas de espécies nativas. O estudo monitorou seis parcelas de 25 x 4 m em uma área restaurada (por semeadura direta em covetas) no bioma Mata Atlântica, localizada no município de Cruzeiro, nos meses de fevereiro de 2021, junho de 2021 e janeiro de 2022. As medidas em indivíduos arbustivos foram a circunferência em altura do peito e a altura da planta. Também inventariamos por cova: diâmetro do dossel, cobertura do dossel e cobertura de grama invasora. Descobrimos que a cobertura do dossel de adubo verde (em relação ao tamanho da planta e do dossel) foi responsável pela diminuição da cobertura de espécies invasoras, nomeadamente espécies de Brachiaria (Urochloa sp.). Além disso, algumas espécies arbustivas apresentaram maior cobertura de dossel que suprimiu espécies invasoras de forma mais eficiente. Também esperávamos que a adubação verde beneficiasse o crescimento de mudas de espécies nativas, mas não encontramos associações entre elas. No entanto, a mudança de estação seca para estação chuvosa na cobertura de copa, juntamente com a presença de gramíneas invasoras, afetou negativamente o crescimento de mudas de espécies nativas. Esses resultados fornecem diretrizes importantes para o sucesso da restauração, geralmente relacionada à diminuição da invasão de gramíneas exóticas e estabelecimento de espécies nativas, indicando o papel da técnica de semeadura direta.
The Atlantic Forest biome, a biodiversity hotspot, has lost most of its native vegetation cover. Active restoration techniques, such as direct seeding, is an important strategy to benefit forest structure formation and to inhibit exotic grass invasion, which is an impediment to many restoration projects. Direct seeding is based on a high density mixture of seeds from large functional/ecological groups (native and exotic “green manure”) sown in well-prepared soil, holes or rows. The main ecological advantage of no-till sites is that they have higher plant density in the early stages, which can benefit the formation of the forest structure and inhibit the invasion of exotic grasses. Sowing combined with green manuring has been used as a strategy for rapid initial cover in degraded soils, helping to control erosion processes and improve soil conditions. Thus, in this study we aimed to investigate the role of green manure canopy on invasive species cover and on growing of native species seedlings in direct seeding sites in the Southeast Atlantic Forest biome. We hypothesized that green manure would suppress cover of exotic grasses and it would benefit native species seedlings growing. The study monitored six plots of 25 x 4 m in a restored area (by direct seeding in pits) belonging to the Atlantic Forest biome, located in Cruzeiro municipality, in February 2021, June 2021 and January 2022. Measurements in individuals were the circumference at breast height and the plant height. We also inventoried per pit: canopy diameter, canopy cover and invasive grass cover. We found that green manure canopy cover (regarding plant size and canopy) was responsible for decreasing invasive species cover, namely Brachiaria species. In addition, some species had higher canopy cover that suppressed invasive species more efficiently. We also expected that green manure would benefit native species seedlings growing, but we did not find associations between them. However, the change from dry season to wet season in canopy cover, together with invasive grasses presence, negatively affected the growing of seedlings of native species. These results provide important guidelines for restoration success, usually related to decrease in exotic grass invasion and establishment of native species, indicating the role of direct seeding technique.
The Atlantic Forest biome, a biodiversity hotspot, has lost most of its native vegetation cover. Active restoration techniques, such as direct seeding, is an important strategy to benefit forest structure formation and to inhibit exotic grass invasion, which is an impediment to many restoration projects. Direct seeding is based on a high density mixture of seeds from large functional/ecological groups (native and exotic “green manure”) sown in well-prepared soil, holes or rows. The main ecological advantage of no-till sites is that they have higher plant density in the early stages, which can benefit the formation of the forest structure and inhibit the invasion of exotic grasses. Sowing combined with green manuring has been used as a strategy for rapid initial cover in degraded soils, helping to control erosion processes and improve soil conditions. Thus, in this study we aimed to investigate the role of green manure canopy on invasive species cover and on growing of native species seedlings in direct seeding sites in the Southeast Atlantic Forest biome. We hypothesized that green manure would suppress cover of exotic grasses and it would benefit native species seedlings growing. The study monitored six plots of 25 x 4 m in a restored area (by direct seeding in pits) belonging to the Atlantic Forest biome, located in Cruzeiro municipality, in February 2021, June 2021 and January 2022. Measurements in individuals were the circumference at breast height and the plant height. We also inventoried per pit: canopy diameter, canopy cover and invasive grass cover. We found that green manure canopy cover (regarding plant size and canopy) was responsible for decreasing invasive species cover, namely Brachiaria species. In addition, some species had higher canopy cover that suppressed invasive species more efficiently. We also expected that green manure would benefit native species seedlings growing, but we did not find associations between them. However, the change from dry season to wet season in canopy cover, together with invasive grasses presence, negatively affected the growing of seedlings of native species. These results provide important guidelines for restoration success, usually related to decrease in exotic grass invasion and establishment of native species, indicating the role of direct seeding technique.
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Palavras-chave
Área de preservação permanente, Restauração ecológica, Muvuca de sementes, Semeadura direta, Permanent preservation area, Ecological restoration, Direct seeding