Acquisitive and conservative growth strategies influence Cedrela fissilis response to drought in two contrasting urban forests in São Paulo, Brazil

Urban forests are crucial for cities’ adaptation to climate change, particularly in megacities like São Paulo, Brazil. This study probes Cedrela fissilis trees’ response to drought in contrasting urban vegetations: a park with planted woodland and an Atlantic Rainforest patch with higher soil-water content, biodiversity, stand age, and density. We assessed the impact of the 2013/14 summer drought, a benchmark for trees’ responses to water stress, using a multiproxy tree-ring approach based on radial growth, wood density, and stable carbon (δ 13 C) and oxygen (δ 18 O) isotope measurements. We hypothesized that trees growing in the urban park adopt an acquisitive strategy, growing faster to the detriment of resistance, recovery, and resilience to drought. The results suggest that trees in the urban park grow 70% faster, exhibiting an acquisitive growth strategy. Despite the distinct growth rates, inter-annual growth variability is driven by precipitation in both sites, and trees reduced the growth rate in response to the drought. In the urban park, δ 13 C and δ 18 O values increased during the drought, suggesting a growth limitation by stomatal control. Conversely, trees from the urban Atlantic Rainforest patch increased wood density by 20% during the drought, a measure against hydraulic failure, suggesting a conservative growth strategy. Although trees showed similar resilience, forest patch trees exhibited a faster recovery, likely due to higher soil-water content combined with the investment in safer hydraulic systems. These findings are site- and sample-specific but point to possible different strategies undertaken by trees under contrasting urban forest formations to cope with climate extremes.