Abstract
<jats:p> Biogenic volatile organic compound (BVOC) emissions from vegetation are major precursors of ozone (O₃) and secondary organic aerosols (SOAs), yet their behavior in tropical megacities remains poorly understood. We quantified BVOC emissions from four native Atlantic Forest tree species: <jats:italic toggle="yes">Alchornea sidifolia</jats:italic> (AS), <jats:italic toggle="yes">Casearia sylvestris</jats:italic> (CS), <jats:italic toggle="yes">Guarea macrophylla</jats:italic> (GM), and <jats:italic toggle="yes">Machaerium nyctitans</jats:italic> (MN), sampled during dry and rainy seasons in two forest remnants of the Metropolitan Area of São Paulo with contrasting anthropogenic influence: Matão-IAG (higher) and RMG (lower). Using dynamic enclosure sampling and TD-GC-MS analysis, we measured emission rates (ERs) and estimated O₃ formation potential (OFP) and SOA potential (SOAP). Species identity was the main factor shaping emission patterns, with sesquiterpenes (SQTs) dominating under all conditions. Four emission strategies emerged. CS showed a high and seasonally variable profile, with the highest ERs, OFP, and SOAP, peaking at RMG during the dry season (11.85, 23.24, and 213.30 µg gDM⁻¹ h⁻¹). AS exhibited moderate and compositionally stable emissions (ER 0.81 to 0.98 µg gDM⁻¹ h⁻¹). GM had moderate and compositionally variable emissions (ER 0.98 to 1.66 µg gDM⁻¹ h⁻¹). MN presented low and compositionally heterogeneous emissions, with a dry-season spike at RMG (ER 2.91 µg gDM⁻¹ h⁻¹). Compound-level analysis revealed potential biomarkers: ledene was associated with the dry season, while 2-ethylhexyl salicylate and β-linalool were linked to urban stress. These findings improve the spatiotemporal characterization of BVOCs in the Atlantic Forest and offer an evidence-based framework for sustainable urban forestry in tropical megacities. </jats:p>