Long-Term Growth Trends of Robinia pseudoacacia in Relation to Climate Change and Industrial Pollution in the Urban Environment of Kraków, Poland

The study investigated Robinia pseudoacacia L. planted in the early 20th century in the urban environment of Kraków (SW Poland). Growth responses for the 1920–2019 period were analyzed against changing climatic conditions and pollution levels. In the second half of the 20th century, atmospheric pollution rose sharply owing to local and regional industrial expansion. From the 1950s, the increase in emissions coincided with higher basal area increment (BAI), which can serve as a vitality index. Growth response homogeneity also increased, indicating similar reactions of individual trees to annual climatic variability, and the climate signal-to-noise ratio (SNR) in the BAI chronology rose. Only after peak emission periods did these indices decline abruptly. R. pseudoacacia, in general, enhanced growth when the previous year to the growth year fulfilled the following: July–September was cool and wet; December, February, and March were mild; November, February, and April–August were rainy; June–July was cool; and September–October was warm. These relationships changed over time. Recent climatic warming combined with stable precipitation and a strong reduction in emissions has promoted R. pseudoacacia growth over the past two decades. This species can therefore be considered in urban greening plans as a stable and resilient provider of cooling, carbon storage, rainwater regulation, and other ecosystem services.