Quantifying Soil Organic Carbon Responses to Fire at the Landscape Scale in the Amazonia

• Grant number: 23/18333-8
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Effective date (Start): February 01, 2024
• Effective date (End): January 31, 2026
• Field of knowledge: Biological Sciences - Ecology - Applied Ecology
• Acordo de Cooperação: NERC, UKRI
• Principal Investigator: Plínio Barbosa de Camargo
• Grantee: Wanderlei Bieluczyk
• Host Institution: Centro de Energia Nuclear na Agricultura (CENA). Universidade de São Paulo (USP). Piracicaba , SP, Brazil
• Associated research grant: 21/00976-4 - Amazon PyroCarbon: quantifying soil carbon responses to fire, AP.TEM

Abstract

In the Amazon, land use change impacts extend beyond converted agricultural landscapes. Human disruption severely affects the regional water cycle, worsening climate extremes like prolonged droughts. Evident in the deforestation arc (Cerrado-Amazon transition) amidst agricultural frontier expansion, this process is degrading nearby primary forests, heightening forest flammability, and increasing recent forest fire frequency and intensity. Standing forests are becoming more vulnerable to fire damage, resulting in significant losses to their vital role in providing ecosystem services, such as nutrient cycling and soil carbon (C) storage. A single forest fire abruptly alters both above and belowground C cycles, while recurring fire events leave long-lasting legacies (e.g., centuries). Yet, Amazon's research falls short in understanding fire's impact on existing soil C and the fate of new charcoal (pyrogenic C; PyC). Within this context, it's crucial to assess landscape-scale changes and dimensioning impacts within (i) standing burned forests, (ii) logged + burned areas, and (iii) secondary forest regeneration post-fire(s). We'll compare these with intact reference forests, using a chronosequence approach to understand soil organic carbon changes across space and time. Various analyses will reveal soil organic matter (SOM) quantity, quality, and origin, as well as the drivers of soil C dynamics during fire-perturbed land transformations. For instance, stable isotopes (e.g., ´13C and ´15N) will be used to investigate temporal sources of SOM with and without previous fire events. Simultaneously to total soil C, PyC contributions will also be quantified. Soil respiration (in situ), stable isotopes, and granulometric soil organic matter fractions will aid in studying the SOM quality. Interconnecting soil C fractions with various chemical, physical, and biological soil properties will elucidate the main drivers of soil C dynamics under fire disturbances. These relations will be integrated, forming the basis for a subsequent comprehensive soil health assessment. Therefore, we will generate a comprehensive and environmentally valuable dataset by conducting a systematic pan-Amazonian analysis of soil carbon dynamics in response to recent fires. This dataset and our data analyses and interpretations will contribute to future modeling, guiding land management strategies, and carbon budgets. It will also assist Brazil in formulating conservation policies to tackle challenges in land use, climate change, and biodiversity preservation in the Amazon. (AU)