A comprehensive experimental assessment of glyphosate ecological impacts in riparian forest restoration

Autor(es)

Florido, Flavia G. ^[1] ; Regitano, Jussara B. ^[2] ; Andrade, Pedro A. M. ^[3] ; Andreote, Fernando D. ^[2] ; Brancalion, Pedro H. S. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Siio Paulo, Luiz de Queiroz Coll Agr, Dept Forest Sci, Ave Padua Dias 11, BR-13418900 Piracicaba, SP - Brazil

^[2] Univ Siio Paulo, Luiz de Queiroz Coll Agr, Dept Soil Sci, Ave Padua Dias 11, BR-13418900 Piracicaba, SP - Brazil

^[3] Univ Siio Paulo, Luiz de Queiroz Coll Agr, Dept Genet, Ave Padua Dias 11, BR-13418900 Piracicaba, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Ecological Applications; v. 32, n. 1 DEC 2021.
• Citações Web of Science: 0

Resumo

Competition with invasive grasses is one of the most important drivers of tree planting failures, especially in tropical forests. A widely disseminated weeding approach has been glyphosate spraying, the most used herbicide globally in forestry and ecosystem restoration. However, glyphosate use in restoration is highly controversial and requires further studies to elucidate its effects on restoration processes and the environment. We evaluated the use of glyphosate in riparian forest restoration and its impacts on tree planting costs, weed control efficiency, planted seedling performance, herbaceous and woody species regeneration, soil bacteria, and environmental contamination, using mowing treatments as a reference and based on a controlled experiment established in the Brazilian Atlantic Forest. Glyphosate spraying reduced by one-half and one-third the accumulated aboveground biomass of, respectively, weeds in general and of the invasive grass Urochloa decumbens compared to mowing treatments, and it reduced the cost by half. The performance of planted tree seedlings was markedly favored by glyphosate spraying compared to mowing treatments, as expressed by improved seedling height (similar to twice higher), crown area (similar to 5x higher), and basal area (similar to 5x higher); the regeneration of both native woody and ruderal herbaceous plants were also enhanced. Neither glyphosate nor its metabolite Aminomethylphosphonic acid (AMPA) residues were detected in either water runoff or soil samples, but they were found at relatively high concentrations in the runoff sediments (from 1.32 to 24.75 mg/kg for glyphosate and from 1.75 to 76.13 mg/kg for AMPA). Soil bacteria communities differed before and after glyphosate spraying in comparison to mowing plots (without glyphosate). Glyphosate spraying was far more cost effective than mowing for controlling U. decumbens and greatly improved the performance of planted tree seedlings and natural regeneration, while not leaving residues in soil and water. However, the changes in the structure of bacterial communities and high concentration of glyphosate and AMPA residues in runoff sediments highlight the need for caution when using this herbicide in riparian buffers. We present alternatives for reducing glyphosate use and minimizing its risks in tree planting initiatives. (AU)

• Processo FAPESP: 12/11256-3 - Controle de plantas competidoras na restauração ecológica
• Beneficiário: Flávia Garcia Flórido
• Modalidade de apoio: Bolsas no Brasil - Mestrado
• Processo FAPESP: 12/19771-4 - Uso de glifosate na restauração de matas ciliares: potencial de poluição do solo e da água e aspectos silviculturais
• Beneficiário: Pedro Henrique Santin Brancalion
• Modalidade de apoio: Auxílio à Pesquisa - Regular