Soil organic matter molecular composition shifts driven by forest regrowth or pasture after slash-and-burn of Amazon Forest.

• Autor(a) principal: LEAL, O. dos A.
• Data de Publicação: 2023
• Outros Autores: JIMÉNEZ-MORILLO, N. T., GONZÁLEZ-PÉREZ, J. A., KNICKER, H., COSTA, F. de S., JIMÉNEZ-MORILLO, P. N., CARVALHO JUNIOR, J. A. de, SANTOS, J. C. dos, DICK, D. P.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da EMBRAPA (Repository Open Access to Scientific Information from EMBRAPA - Alice)
• Texto Completo: http://www.alice.cnptia.embrapa.br/alice/handle/doc/1151856; https://doi.org/10.3390/ijerph20043485
• topic: Derruba-e-queima; Slash-and-burn agriculture; Amazônia Ocidental; Asentamiento humano; Acrisoles; Regeneración natural; Materia orgánica del suelo; Pastizales; Química del suelo; Molecular composition; Composição molecular; Composición molecular; Nitroalkanes; Nitroalcanos; Van Krevelen 3D diagram; Analytical pyrolysis; Assentamento Santa Luzia (AC); Cruzeiro do Sul (AC); Acre; Western Amazon; Amazonia Occidental; Sistema de Cultivo; Cultivo Migratório; Regeneração Natural; Pastagem; Brachiaria; Química do Solo; Solo; Matéria Orgânica; Human settlements; Shifting cultivation; Acrisols; Natural regeneration; Soil organic matter; Pastures; Soil chemistry

Slash-and-burn of Amazon Forest (AF) for pasture establishment has increased the occurrence of AF wildfires. Recent studies emphasize soil organic matter (SOM) molecular composition as a principal driver of post-fire forest regrowth and restoration of AF anti-wildfire ambience. Nevertheless, SOM chemical shifts caused by AF fires and post-fire vegetation are rarely investigated at a molecular level. We employed pyrolysis-gas chromatography-mass spectrometry to reveal molecular changes in SOM (0?10, 40?50 cm depth) of a slash-burn-and-20-month-regrowth AF (BAF) and a 23-year Brachiaria pasture post-AF fire (BRA) site compared to native AF (NAF). In BAF (0-10 cm), increased abundance of unspecific aromatic compounds (UACs), polycyclic aromatic hydrocarbons (PAHs) and lipids (Lip) coupled with a depletion of polysaccharides (Pol) revealed strong lingering effects of fire on SOM. This occurs despite fresh litter deposition on soil, suggesting SOM minimal recovery and toxicity to microorganisms. Accumulation of recalcitrant compounds and slow decomposition of fresh forest material may explain the higher carbon content in BAF (0?5 cm). In BRA, SOM was dominated by Brachiaria contributions. At 40?50 cm, alkyl and hydroaromatic compounds accumulated in BRA, whereas UACs accumulated in BAF. UACs and PAH compounds were abundant in NAF, possibly air-transported from BAF.