DECCA · How Deforestation is Changing the Climate and Atmospheric Chemistry over Amazonia

The Amazon rainforest, renowned as the world's largest, plays a pivotal role in biodiversity, water cycles, atmospheric chemistry, and global climate. However, this vital ecosystem is progressively succumbing to vulnerabilities triggered by climate change and deforestation. Main drivers of deforestation are the expansion of pasture and agriculture. Over the past decade, these activities have surged, underscoring the pressing need for a scientific comprehension of the impacts of deforestation across Amazonia. To tackle this challenge, DECCA is adopting a multifaceted approach. First, through rigorous laboratory investigations, DECCA is scrutinizing the impacts of deforestation types on soil microbial community distribution, along with emissions of greenhouse gases (GHGs, carbon dioxide+methane+nitrous oxide) and reactive nitrogen (Nr, nitrous acid+nitrogen oxides+ammonia). By analyzing soil samples from different land use categories—ranging from pristine forests to areas converted to livestock and agricultural use—DECCA aims to quantify GHGs and Nr fluxes. This initiative encompasses an exploration of the influencing factors that drive GHGs and Nr emissions, ultimately enabling the establishment of emission parameters. Second, combined with a chemistry-transport model, DECCA quantifies the impact of deforestation on atmospheric chemistry and composition. This extends to understanding the formation of critical elements like ozone, aerosols, and cloud condensation nuclei. Third, a process-based biogeochemistry model is employed to estimate total GHG emissions for understanding GHG budgets and their climate implications. Moreover, DECCA incorporates predictions of land use evolution up to 2050, enabling supplementary model simulations for future deforestation scenarios. Thus, DECCA leads an interdisciplinary endeavor, enhancing our grasp of deforestation impacts across molecular, ecosystem-wide, and atmospheric scales.