Long-term carbon storage in Brazilian Cerrado soils – a conjunction of wildfires, bioturbation, and local edaphic controls on vegetation

• Published in: Plant and soil Vol. 484; no. 1-2; pp. 645 - 662
• Main Authors: Schellekens, Judith, Justi, Marina, Macedo, Rodrigo, Calegari, Márcia Regina, Buurman, Peter, Kuyper, Thomas W., Barbosa de Camargo, Plínio, Vidal-Torrado, Pablo
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01.03.2023; Springer; Springer Nature B.V
• Subjects: Agriculture; Analysis; Biomedical and Life Sciences; Bioturbation; Carbon 14; Carbon content; Carbon sequestration; Charcoal; Composition; Ecology; Ecosystems; Geomorphology; Grasses; Life Sciences; Macrofauna; Moisture content; Organic carbon; Organic matter; Organic soils; Plant Physiology; Plant Sciences; Radiocarbon dating; Research Article; Soil organic matter; Soil profiles; Soil properties; Soil Science & Conservation; Soil stability; Soil water; Soils; Stability analysis; Total organic carbon; Trees; Vegetation; Vegetation patterns; Water availability; Wildfires; Brazil; Bioturbation; N isotopic composition; Umbric Ferralsols; C and; Black carbon; Cerrado ecosystems
• ISSN: 0032-079X; 1573-5036
• DOI: 10.1007/s11104-022-05824-4

Purpose The objective of this study is to improve our understanding of soil organic matter (SOM) stability in Brazilian Cerrado, by interpreting soil properties at the ecosystem scale and elaborating on the interactions of biotic, climatic and edaphic controls. Methods Three 2 m soil profiles with significantly different total organic carbon TOC content but located on the same geomorphological unit were studied for δ 13 C isotopic composition to connect tree-grass patterns to TOC content. To gain insight into soil carbon stability, C/N, δ 13 C and δ 15 N were analysed for functional organic matter (OM) pools: free particulate OM (POM), occluded POM, base-extractable OM, and mineral-associated OM. Results Small but abrupt shifts of δ 13 C with depth reflected simultaneous changes in tree-grass vegetation patterns over the past 10,000 years in all three profiles. These temporal changes were superimposed on spatial differences as indicated by consistent differences in δ 13 C values between the profiles, reflecting that site-specific differences in tree-grass patterns persisted over the past 10,000 years. Profiles with a historically larger contribution from trees (as evidenced by lower δ 13 C) had increased charcoal contents. Downward movement of charcoal by intense bioturbation occurred faster in the OM-rich soils as suggested by 14 C dating. Conclusion We found that long-term carbon storage in Brazilian Cerrado soils was a conjunction of wildfires, bioturbation, and local edaphic controls on tree-grass composition. Soils with an OM-rich thick A-horizon had more trees, more charcoal, and a higher activity of soil macrofauna, which was related to local differences in soil water availability.