Dynamics of palm tree invasion control in an urban remnant of the Atlantic Forest

Abstract

Biological invasions are a major driver of biodiversity change, particularly in disturbed urban forests where propagule pressure favors opportunistic species. Here, we document the demographic expansion and biomass contribution of the invasive Australian palm Archontophoenix cunninghamiana H.Wendl. & Drude in an urban Atlantic Forest remnant in São Paulo, a subtropical megacity in southeastern Brazil. Using one hectare of permanent plots monitored between 2017 and 2022, we quantified palm density and assessed changes following management actions implemented by municipal authorities. We also compiled official data on removed individuals in 2021 and estimated aboveground biomass using the allometric model of Hughes et al., (1999). Prior to management, density reached 391 individuals ha⁻¹, decreasing to 138 individuals ha⁻¹ after removal. Official records indicated the removal of 738 individuals, storing 3.3 tons of aboveground biomass, with medium-to-large individuals contributing most to biomass stock. Despite its carbon storage, the high density and regenerative success of A. cunninghamiana relative to native palms may intensify biotic homogenization and threaten recruitment dynamics in urban forest remnants and adjacent Atlantic Forest landscapes. Our findings highlight the need for coordinated prevention and management to reduce propagule pressure from ornamental plantings and limit invasion spread across metropolitan forest fragments.